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<title>Observational or social learning</title></titleStmt>

<publicationStmt><distributor>BASE and Oxford Text Archive</distributor>


<availability><p>The British Academic Spoken English (BASE) corpus was developed at the

Universities of Warwick and Reading, under the directorship of Hilary Nesi

(Centre for English Language Teacher Education, Warwick) and Paul Thompson

(Department of Applied Linguistics, Reading), with funding from BALEAP,

EURALEX, the British Academy and the Arts and Humanities Research Board. The

original recordings are held at the Universities of Warwick and Reading, and

at the Oxford Text Archive and may be consulted by bona fide researchers

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<p>1. The recordings and transcriptions should not be modified in any


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<p>3. The recordings and transcriptions should not be reproduced in full for

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Researchers should acknowledge their use of the corpus using the following

form of words:

The recordings and transcriptions used in this study come from the British

Academic Spoken English (BASE) corpus, which was developed at the

Universities of Warwick and Reading under the directorship of Hilary Nesi

(Warwick) and Paul Thompson (Reading). Corpus development was assisted by

funding from the Universities of Warwick and Reading, BALEAP, EURALEX, the

British Academy and the Arts and Humanities Research Board. </p></availability>




<recording dur="00:55:32" n="8824">


<respStmt><name>BASE team</name>



<langUsage><language id="en">English</language>



<person id="nf1207" role="main speaker" n="n" sex="f"><p>nf1207, main speaker, non-student, female</p></person>

<personGrp id="ss" role="audience" size="m"><p>ss, audience, medium group </p></personGrp>

<personGrp id="sl" role="all" size="m"><p>sl, all, medium group</p></personGrp>

<personGrp role="speakers" size="3"><p>number of speakers: 3</p></personGrp>





<item n="speechevent">Lecture</item>

<item n="acaddept">Psychology</item>

<item n="acaddiv">ss</item>

<item n="partlevel">UG1</item>

<item n="module">Psychobiology of learning</item>




<u who="nf1207"> <kinesic desc="overhead projector is on showing transparency" iterated="n"/> one on learning <pause dur="0.5"/> next week <pause dur="0.4"/> Dr <gap reason="name" extent="1 word"/> will be starting <pause dur="0.5"/> the final section of this psychobiology course but this is the last one of mine <pause dur="0.9"/> and as i indicated in my last lecture <pause dur="0.8"/> up till now <pause dur="1.4"/> would you stop talking please <pause dur="0.5"/> thank you <pause dur="0.7"/> up till now <pause dur="0.6"/> i've been talking about animals learning individually <pause dur="0.8"/> and in this last lecture i'm going to talk a bit about <pause dur="0.5"/> what animals learn in the company of other animals in particular <pause dur="0.5"/> whether they learn from observing other animals and if so what <pause dur="1.2"/> # <pause dur="0.4"/> the terminology i'll be using is that i'll be talking about <pause dur="0.6"/> quite a lot of experiments where some animals are observers that is they watch other animals performing <pause dur="0.6"/> and <pause dur="0.3"/> and <pause dur="1.0"/> other animals are the demonstrators or models that is they perform something <pause dur="0.2"/> or behave in a certain way <pause dur="0.3"/> and we want to know what the observers learn <pause dur="0.4"/> from <pause dur="0.3"/> watching the demonstrators or models <pause dur="0.6"/> well what might they learn <pause dur="1.2"/> basically the two kinds of things that they might learn correspond to the two kind of individual <pause dur="0.6"/> sorts of associative

learning <pause dur="0.4"/> that i've been talking about in these lectures so far <pause dur="0.5"/> for example animals might learn from one another <pause dur="0.4"/> the significance of stimuli <pause dur="0.3"/> what foods are good or bad to eat <pause dur="0.4"/> what things are predators <pause dur="0.3"/> these are the kind of things that we know they can learn individually through Pavlovian conditioning <pause dur="0.3"/> but maybe they can learn it from watching other animals what other animal eat what other animals avoid as well <pause dur="0.9"/> the other kind of new learning i talked about in my last lecture <pause dur="0.4"/> is learning new actions <pause dur="0.5"/> for example <pause dur="0.3"/> learning how to get at or handle food <pause dur="0.7"/> this is the sort of thing that animals can learn individually through instrumental conditioning as i discussed in my last lecture <pause dur="0.4"/> perhaps they can also learn it to some extent <pause dur="0.3"/> by watching other animals <pause dur="0.4"/> and the two the sections of this lecture <pause dur="0.4"/> refer to experiments in which these two potential kinds of social learning are studied <pause dur="1.3"/> before talking about experiments <pause dur="0.2"/> i want to talk a bit about the kind of naturalistic

data <pause dur="0.4"/> which suggest to people <pause dur="0.3"/> that this observational or social learning goes on <pause dur="0.5"/> that animals learn things from other animals in their social group or culture <pause dur="0.3"/> which they would not learn in other situations <pause dur="1.4"/> well <pause dur="0.2"/> there is lots of apparent evidence which has been interpreted as evidence of social learning <pause dur="0.6"/> for example if you look at different colonies or troops of chimps the same species <pause dur="0.4"/> but living in different parts of Africa <pause dur="0.5"/> you find that different <trunc>ch</trunc> <pause dur="0.5"/> troops show different behaviours <pause dur="0.4"/> for example some troops of <pause dur="0.2"/> chimps <pause dur="0.3"/> build nests in trees <pause dur="0.2"/> others don't <pause dur="0.7"/> is it possible that the troops that show this behaviour <pause dur="0.4"/> have learned it by <pause dur="0.6"/> joint learning by copying each other <pause dur="0.3"/> whereas the troops that don't show it have simply not had any demonstrators around so haven't had the opportunity to learn <pause dur="0.7"/> similarly <pause dur="0.3"/> certain specialized kinds of food getting behaviour <pause dur="0.6"/> there's a behaviour <trunc>i</trunc> a well known behaviour <pause dur="0.4"/> observed in chimps by Jane van Lawick-Goodall <pause dur="0.5"/> # which is termite fishing <pause dur="0.4"/> where <pause dur="0.4"/> a

skilled chimp chimps <pause dur="0.2"/> feed off termites which are little ant-like creatures which live in mounds <pause dur="0.6"/> the termites have <pause dur="0.3"/> holes through which they enter and exit from the mound <pause dur="0.6"/> and chimps in some <pause dur="0.3"/> colonies <pause dur="0.3"/> have learned <pause dur="0.6"/> to <pause dur="0.4"/> get twigs or branches <pause dur="0.2"/> strip off the leaves from these twigs so they are nice and thin and pointed <pause dur="0.5"/> and poke the twigs down the holes into the termite mound sit and wait <pause dur="0.6"/> eventually termites will crawl on to the stick <pause dur="0.2"/> at which point the chimp whips the stick out and eats the termites off the stick <pause dur="0.7"/> now this is a quite a skilled behaviour <pause dur="0.3"/> but it's a very cunning way of getting termites out of mounds <pause dur="0.6"/> and <pause dur="0.2"/> it's shown by some chimps and not others <pause dur="0.2"/> and more to the point <pause dur="0.4"/> young chimps have been observed <pause dur="0.2"/> watching their mothers do this <pause dur="0.6"/> and the question arises <pause dur="0.2"/> to what extent do chimps learn this skill by watching their mothers <pause dur="1.1"/> # <pause dur="0.8"/> another example <pause dur="0.8"/> of a similar kind <pause dur="0.4"/> which i mentioned in my last lecture <pause dur="0.5"/> is illustrated in this overhead <pause dur="0.8"/> it shows <pause dur="0.2"/> black rats <pause dur="0.3"/> i said in

my last lecture black squirrel that was a mistake it's black rats <pause dur="0.6"/> feeding off pine cones <pause dur="0.4"/> you remember i said that black rats <pause dur="0.2"/> get quite skilled <pause dur="0.4"/> at stripping the exterior off pine cones so they can get at the kernels in the middle <pause dur="0.7"/> well adult rats of course do this skilfully <pause dur="0.4"/> and in the wild it's very often the case that young rats <pause dur="0.6"/> feed together with their parents <pause dur="0.6"/> watch them <pause dur="0.2"/> while they're feeding off pine cones and attempt to feed off pine cones at <trunc>thems</trunc> themselves at the same time <pause dur="0.5"/> so the question is <pause dur="0.3"/> to what extent are the young rats <pause dur="0.2"/> learning this skill <pause dur="0.3"/> by watching <pause dur="0.2"/> the black rats <pause dur="1.2"/> well you might say what are the alternatives the answer is there are lots of alternatives <pause dur="0.7"/> one possibility is just that <pause dur="0.3"/> young rats <pause dur="0.9"/> tend to <pause dur="0.3"/> follow their parents around <pause dur="0.3"/> so when the parents <pause dur="0.2"/> are among pine cones and picking them up <pause dur="0.4"/> the young rat <pause dur="0.2"/> also just because it's accompanying the adult rat <pause dur="0.3"/> will also be in the presence of pine cones <pause dur="0.2"/> also pick them up <pause dur="0.5"/> and it may learn the behaviour <pause dur="0.2"/>

individually <pause dur="0.4"/> but just <pause dur="0.3"/> because it follows its rat it tends to do it its parent it tends to do it in the company of parents <pause dur="1.6"/> a slightly more sophisticated thing that the young rat might be learning <pause dur="0.3"/> is that pine cones are good <pause dur="0.9"/> they might be learning because their mothers <pause dur="0.4"/> spend a lot of time with pine cones <pause dur="0.2"/> there might be a kind of higher order conditioning going on <pause dur="0.4"/> whereas they associate pine cones with something good <pause dur="0.3"/> and therefore are attracted to pine cones themselves <pause dur="0.3"/> and to try to <pause dur="0.5"/> # try to get # <trunc>t</trunc> <pause dur="0.2"/> try them out <pause dur="0.4"/> and learn by themselves <pause dur="1.1"/> this <pause dur="0.4"/> what i'm getting at is that there are a number of simpler kinds of individual learning <pause dur="0.6"/> that might contribute <pause dur="0.3"/> to the young rats <pause dur="1.3"/> <trunc>i</trunc> <pause dur="0.2"/> to the way the young rat itself learns to interact with pine cones <pause dur="0.3"/> which do not necessarily involve <pause dur="0.4"/> the young rat <pause dur="0.3"/> actively learning its mother's actions <pause dur="0.3"/> or still less being taught by its mother <pause dur="0.9"/> as i have so often said in these lectures <pause dur="0.3"/> you have to discount simpler explanations <pause dur="0.3"/> before you can accept more complex

explanations <pause dur="0.3"/> of what in this case the young black rat is learning <pause dur="0.6"/> so <pause dur="0.3"/> in the <pause dur="0.2"/> in <pause dur="0.6"/> in the later part of this lecture i'll be talking about how experimentally <pause dur="0.3"/> one might be able to distinguish between these <pause dur="0.4"/> rather simple explanations that what the young rat is doing individual learning but somehow enhanced by the presence of its mother <pause dur="0.5"/> or whether the young rat <kinesic desc="changes transparency" iterated="y" dur="4"/> is really learning something by watching its mother <pause dur="0.5"/> that's the sort of question we have to address <pause dur="2.3"/> there are other <pause dur="2.2"/> there's another very well known example that i want to mention briefly and come back to at the end of this lecture <pause dur="0.6"/> which is the <pause dur="0.6"/> macaques in Japan macaques are a kind of monkey <pause dur="0.3"/> kind of rhesus monkey <pause dur="0.7"/> the macaques in Japan <pause dur="0.3"/> who learned to wash food <pause dur="1.2"/> they were <pause dur="0.4"/> these were macaques on an <pause dur="0.3"/> island colony <pause dur="0.5"/> which was <pause dur="0.2"/> provisioned artificially fed <pause dur="0.3"/> by people <pause dur="0.7"/> among the food they fed them <pause dur="0.3"/> were sweet potatoes <pause dur="0.6"/> these sweet potatoes tended to get sandy and dirty when they were lying on the ground <pause dur="0.6"/> and it was observed <pause dur="0.3"/> that

certain individual macaques <pause dur="0.4"/> acquired the behaviour <pause dur="0.3"/> of dipping the potatoes in water or dropping them in water and then taking them out before eating them so they were nice and clean <pause dur="1.2"/> this behaviour was <pause dur="0.3"/> initially observed in a very small number of animals in fact in just one animal initially <pause dur="0.4"/> but it gradually spread through the colony more and more animals showed it <pause dur="0.6"/> and the question was <pause dur="0.2"/> was this social learning <pause dur="0.2"/> were the macaques learning from each other <pause dur="0.4"/> that it was a good idea to dip food in the water <pause dur="0.4"/> i'll come back to this question at the end of the lecture <pause dur="0.6"/> i won't stop with the rats diving for shellfish example because <pause dur="0.3"/> # i don't really have time but there are <pause dur="0.4"/> other examples where specialized behaviour such as diving <pause dur="0.4"/> to get shellfish from the bottom of a river <pause dur="0.4"/> are shown in just some colonies of animals <pause dur="0.3"/> and not others <pause dur="1.0"/> as i've tried to indicate <pause dur="0.3"/> these kind of observations while very fascinating <pause dur="0.3"/> do not themselves provide evidence of social learning <pause dur="1.0"/> i <pause dur="0.2"/>

argued this in some detail in the case of the black rat <pause dur="0.3"/> but we can argue it more generally by saying that <pause dur="0.4"/> when you see a behavioural difference between different colonies of animals <pause dur="0.6"/> this might be due to learning <pause dur="0.3"/> social learning going on in one colony and not the other <pause dur="0.6"/> or it might be due to particular environmental conditions which are present in one group and not in another <pause dur="1.0"/> for example <pause dur="0.3"/> chimps who build nests <pause dur="0.4"/> might do so because the particular trees that they have exploited <pause dur="0.4"/> provide suitable material for making nests <pause dur="0.4"/> an environmental factor <pause dur="0.7"/> whereas chimps in other areas <pause dur="0.2"/> don't have such suitable trees perhaps if the chimps in other areas had suitable trees <pause dur="0.3"/> they too would learn to build nests <pause dur="0.2"/> individually <pause dur="1.2"/> # <pause dur="1.3"/> with the macaques watching washing food <pause dur="0.4"/> it could be that <pause dur="0.5"/> all the individual macaques are learning this by trial and error by instrumental conditioning without necessarily learning from each other <pause dur="0.5"/> and so on <pause dur="0.7"/> so <pause dur="0.4"/> we need some way <pause dur="0.6"/> to <pause dur="0.7"/> do controlled studies which <pause dur="0.2"/>

manipulate <pause dur="0.3"/> what opportunities animals actually have to learn from each other <pause dur="0.5"/> and see whether they do in fact learn <pause dur="0.4"/> in the way <pause dur="0.2"/> that <pause dur="0.5"/><kinesic desc="changes transparency" iterated="y" dur="4"/> that is being speculated <pause dur="2.0"/><vocal desc="cough" iterated="n"/><pause dur="1.0"/> my first set of examples come from <pause dur="0.5"/> <trunc>a</trunc> and and i'm going to talk about some fairly classic experiments in this lecture <pause dur="0.5"/> but <pause dur="0.9"/> i would point out before i go on that there is a really excellent chapter <pause dur="0.2"/> on this subject <pause dur="0.6"/> in Shettleworth's book <pause dur="0.8"/> which is <pause dur="0.2"/> referred to <pause dur="0.6"/> in <pause dur="0.7"/> the <pause dur="0.3"/> reference list for this lecture Sara Shettleworth has a superb chapter <pause dur="0.4"/> on <pause dur="0.2"/> social learning it's called learning from others <pause dur="0.3"/> it's very up to date <pause dur="0.2"/> very thoughtful very comprehensive <pause dur="0.6"/> and i'm going to mention just a few of the examples that she mentions but <pause dur="0.5"/> if you seriously want to think about this area and it involves many complexities <pause dur="0.4"/> her chapter is a very good place to go <pause dur="1.8"/> anyway <pause dur="0.8"/> some of the best known work <pause dur="0.2"/> on <pause dur="0.9"/> social learning <pause dur="0.2"/> or <pause dur="0.3"/> putative social learning <pause dur="1.1"/> in rats <pause dur="0.4"/><kinesic desc="changes transparency" iterated="y" dur="3"/> in animals <pause dur="0.5"/> are about food preferences <pause dur="0.3"/> these are examples of learning the significance of

stimuli <pause dur="0.3"/> learning what foods are good to eat <pause dur="0.2"/><kinesic desc="changes transparency" iterated="y" dur="1"/> and what foods are bad to eat <pause dur="0.7"/> and as i pointed out in connection with the young black rats <pause dur="0.8"/> many animals eat <pause dur="0.2"/> in a social situation <pause dur="0.3"/> they will eat in the company of other rats <pause dur="0.4"/> for <trunc>ex</trunc> rats will eat in the company of other rats young rats will often eat in the company of their <pause dur="0.4"/> adult <pause dur="0.2"/> companions <pause dur="0.6"/> so <pause dur="0.5"/> the question arises what do they learn <pause dur="1.9"/> for example it's very well known <pause dur="0.3"/> that <pause dur="0.3"/> young rats will tend to prefer the same foods that their parents eat <pause dur="1.0"/> and in a simple experimental demonstration of this <pause dur="0.4"/> Galef <pause dur="1.2"/> got some <pause dur="0.2"/> adult rats <pause dur="0.7"/> and trained them by prior training <pause dur="0.3"/> using the taste aversion learning <pause dur="0.2"/> procedure that i talked about last week <pause dur="0.8"/> that a certain kind of food A <pause dur="0.2"/> was good to eat <pause dur="0.8"/> but they also learned to avoid another kind of food B <pause dur="0.2"/> by means of taste aversion learning <pause dur="0.5"/> so the adults prior to the start of experiment <pause dur="0.3"/> had learned that food A was good to eat and food B was nasty <pause dur="0.9"/> and they were provided with both foods A and B <pause dur="0.7"/> and then young rats <pause dur="0.3"/>

were put in with the parents and allowed to accompany them while eating <pause dur="1.0"/> and of course <pause dur="0.4"/> naturally <pause dur="0.4"/> the parents ate lots of food A but avoided food B <pause dur="0.5"/> and naturally the young rats <pause dur="0.2"/> did the same <pause dur="0.3"/> if they were subsequently offered a choice between A and B <pause dur="0.3"/> the young rats would also prefer A <pause dur="0.9"/> the question is what had they learned <pause dur="0.2"/> from the parents <pause dur="0.5"/> the first basic question is <pause dur="0.3"/> had they learned that food A is good <pause dur="0.6"/> had they learned that food B is bad <pause dur="0.4"/> the parents knew both these things <pause dur="0.6"/> but had the young rats learned both these things had the adults communicated if you like to the young rats <pause dur="0.4"/> both that food A is good <pause dur="0.5"/> and that food B is bad <pause dur="0.9"/> to test this Galef did the following simple experiment <pause dur="0.3"/> he tested the young rats alone <pause dur="1.1"/> with food A versus a novel food that they'd never had before <pause dur="0.7"/> if the young rats know that food A is good <pause dur="0.2"/> they should prefer it to the novel food <pause dur="0.2"/> and they did <pause dur="0.8"/> so the young rats had clearly learned a preference of food A <pause dur="1.6"/> now to test whether the young rats had learned to avoid food B <pause dur="0.3"/> he tested them again on their own<pause dur="0.3"/> with B versus C <pause dur="0.6"/>

if they learned from their parents that food B was bad <pause dur="0.3"/> they should have avoided food B <pause dur="0.2"/> and preferred the novel food <pause dur="0.2"/> C <pause dur="0.3"/> but they didn't they showed no preference at all <pause dur="0.8"/> in other words <pause dur="0.4"/> although the adults rats knew <pause dur="0.2"/> that food B was bad <pause dur="0.3"/> they had not transmitted this knowledge <pause dur="0.2"/> to the young rats <pause dur="1.1"/> so <pause dur="0.3"/> the young rats have learned to behave to some extent in a similar way to the adults <pause dur="0.3"/> but they had not <pause dur="0.6"/> learned all the information that the adults knew <pause dur="0.8"/> they had learned that A is safe but they'd not learned that B is dangerous <pause dur="0.8"/> and this simple experiment <pause dur="0.2"/> makes a very general point <pause dur="0.4"/> that just because <pause dur="0.5"/> an animal <pause dur="0.5"/> behaves the same way as another <pause dur="0.3"/> doesn't mean it's acquired all the knowledge that the other has there may be simpler means <pause dur="0.3"/> by which the young rats <pause dur="0.2"/> come to behave in the same way as the adults <pause dur="1.7"/> for example <pause dur="0.4"/> it might simply be that <pause dur="0.4"/> food A has become very familiar <pause dur="0.2"/> to the young rats <pause dur="0.3"/> if you imagine what's happening <pause dur="0.2"/> food A is over here food B is over here <pause dur="0.6"/> the adults eat a lot of food A <pause dur="0.3"/>

ignore food B <pause dur="0.6"/> the young rats follow the parents eat where they're eating <pause dur="0.4"/> so necessarily the young rats eat a lot of food A as well <pause dur="0.4"/> just because they're spending a lot of time next to the parents <pause dur="1.1"/> what that means is that food A will become very familiar to the young rats <pause dur="0.6"/> food B will remain very unfamiliar <pause dur="0.6"/> and that in itself would just be a reason <pause dur="0.2"/> for the young rats to prefer A <pause dur="0.6"/> because animals as i've mentioned earlier in these lectures <pause dur="0.3"/> prefer familiar foods to novel ones <pause dur="0.6"/> it might simply be familiarity it might be nothing more than that <pause dur="4.4"/><event desc="takes off transparency" iterated="n"/> that simple experiments can't tell us which <pause dur="3.4"/> now <pause dur="2.7"/> the next experiment i'm going to talk about is one where adult rats <pause dur="0.7"/> learned <pause dur="0.2"/> by interacting with each other <pause dur="0.6"/> about <pause dur="0.3"/> what foods were good to eat <pause dur="0.4"/> so now we're talking about pairs of adult rats <pause dur="0.3"/> not young and adult rats <pause dur="0.7"/> and here <pause dur="0.4"/> the situation is much simplified because we don't have the situation where the young rats follow their parents around it's not a <pause dur="0.5"/> it's a much more straightforward situation <pause dur="0.7"/>

the basic <pause dur="0.5"/> experimental observation <pause dur="0.2"/> which these studies are <pause dur="0.2"/> so which start from is this <pause dur="0.7"/> supposing you let <pause dur="0.2"/> one rat a demonstrator <pause dur="0.5"/> feed on a particular kind of food <pause dur="1.7"/> let's say it feeds on chocolate flavoured powder <pause dur="2.1"/> you then <pause dur="0.7"/> take that rat <pause dur="0.2"/> and put it in a cage with another rat <pause dur="0.2"/> who's never had chocolate powder before <pause dur="1.1"/> there is no chocolate powder present <pause dur="0.6"/> but the two rats will socially interact with each other <pause dur="0.2"/> and a lot of that social interaction involves <pause dur="0.3"/> sniffing <pause dur="0.5"/> licking <pause dur="0.6"/> grooming <pause dur="0.6"/> so that <pause dur="0.5"/> the <pause dur="0.4"/> observer rat the one whose never eaten chocolate powder before <pause dur="0.3"/> has a lot of opportunity <pause dur="0.3"/> to interact with the rat who's eaten chocolate and perhaps smell that food <pause dur="0.4"/> on the rat <pause dur="1.7"/> on on the demonstrator rat <pause dur="0.9"/> and you might well think <pause dur="0.3"/> that the <pause dur="0.3"/> observer rat would acquire a preference for chocolate <pause dur="0.2"/> as a result of this experience and indeed that's what happens <pause dur="0.8"/> observer rats who've been put in with a demonstrator who's previously fed on chocolate <pause dur="0.3"/> if they're then given a choice

between chocolate and some other novel food <pause dur="0.3"/> they will prefer chocolate <pause dur="0.6"/> so clearly they're learning something <pause dur="0.3"/> from their encounter with the other adult <pause dur="0.8"/> but what exactly are they learning <pause dur="2.2"/><vocal desc="cough" iterated="n"/><pause dur="1.0"/><kinesic desc="changes transparency" iterated="y" dur="2"/> Galef did a series of experiments where he kind of simplified <pause dur="0.7"/> the information <pause dur="0.7"/> that the <pause dur="0.4"/> observer rats were getting by means of this simple apparatus <pause dur="0.4"/> rather than letting the rats interact with each other <pause dur="0.4"/> and giving the opportunity for all sorts of potential <pause dur="0.2"/> social transmission <pause dur="0.6"/> he simplified the situation so that he could present <pause dur="0.5"/> the <pause dur="0.2"/> the <pause dur="0.2"/> observer rat here <pause dur="0.5"/> with a very simplified version of the information <pause dur="0.2"/> from the demonstrator <pause dur="0.4"/> he did it by putting <pause dur="0.4"/> the observer rat in this kind of bucket affair <pause dur="0.6"/> in the wall of the bucket <pause dur="0.3"/> was just a tube <pause dur="0.3"/> in which another rat <pause dur="0.2"/> could be placed <pause dur="0.6"/> so it was not possible for this other rat to actually get in the bucket with the observer <pause dur="0.7"/> but the observer <pause dur="0.2"/> could <pause dur="0.2"/> <trunc>int</trunc> could <pause dur="1.0"/> be exposed to <pause dur="0.2"/> whatever sensory stimuli were coming <pause dur="0.3"/> from the demonstrator rat <pause dur="0.5"/> and the

demonstrator rat <pause dur="0.3"/> had eaten <pause dur="0.2"/> a particular food <pause dur="1.0"/> and the question is under what circumstances <pause dur="0.3"/> would the <pause dur="0.2"/> observer rat <pause dur="0.2"/> learn to prefer the food <pause dur="0.2"/> that the demonstrator had eaten <pause dur="0.4"/> ignore these graphs 'cause i'm just going to summarize <pause dur="0.3"/> the results <pause dur="0.3"/> of these studies <pause dur="1.3"/> in a moment in fact this is <pause dur="0.2"/> this is number three on your handout <pause dur="1.6"/><kinesic desc="changes transparency" iterated="y" dur="2"/> so <pause dur="0.6"/> i've described the general <pause dur="0.5"/> # the general procedure <pause dur="0.9"/> what do observer rats learn <pause dur="0.3"/> when they have the opportunity to experience another food <pause dur="0.4"/> that <pause dur="0.2"/> # <trunc>th</trunc> <pause dur="0.5"/> another rat who has eaten a particular food <pause dur="0.9"/> and <pause dur="0.5"/> the observer rats were exposed to food X in a number of different ways <pause dur="0.3"/> and then on their own in the absence of the demonstrator <pause dur="0.3"/> they were given a <trunc>p</trunc> a choice between X and another food Y <pause dur="0.4"/> to see if they'd <pause dur="0.2"/> learned a preference <pause dur="0.6"/><kinesic desc="reveals covered part of transparency" iterated="n"/> and these were the kind of <pause dur="0.6"/> exposures that <pause dur="0.3"/> Galef could make in his bucket apparatus <pause dur="0.8"/> first of all you could have food X <pause dur="1.1"/> # <pause dur="0.9"/> smeared on the nose or mouth of the demonstrator rat <pause dur="0.8"/> and the demonstrator rat was just a normal awake rat <pause dur="0.3"/> so the observer <pause dur="0.3"/> could <pause dur="0.2"/>

smell <pause dur="0.2"/> the food <pause dur="0.7"/> on the rat's face <pause dur="0.6"/> and also potentially maybe exchange some kind of information with the demonstrator <pause dur="1.5"/> the next <trunc>ex</trunc> the next condition was just the same except that the demonstrator rat was anaesthetized so it couldn't <pause dur="0.3"/> actively <pause dur="0.2"/> interact with the observer in any way <pause dur="0.4"/> but the food was still there on its nose and mouth <pause dur="1.2"/> in a third condition <pause dur="0.9"/> the rat who had the <pause dur="0.3"/> food on its nose and mouth <pause dur="0.3"/> was actually not alive <pause dur="0.9"/> the only difference was that <pause dur="0.3"/> in this case it was anaesthetized in this case it wasn't alive <pause dur="1.2"/> and <pause dur="0.4"/> you can see if you look at the result of the first three conditions <pause dur="0.4"/> that <pause dur="0.4"/> observers <pause dur="0.3"/> learned a preference for food X <pause dur="0.5"/> if they'd smelled it on the nose and mouth <pause dur="0.5"/> of a rat who was either awake or anaesthetized <pause dur="0.4"/> but not if they'd smelled it on the nose of the or mouth of a rat who was not alive <pause dur="1.3"/> it's important to realize people tend to assume that somehow <pause dur="0.7"/> the rats in condition three <pause dur="0.6"/> were <pause dur="0.2"/> avoiding a food 'cause it had been on the nose of the dead rat that's not the case at

all they didn't avoid it <pause dur="0.7"/> they just treated it exactly the same as the other <pause dur="0.2"/> novel food they just treated it as it was completely unfamiliar they didn't avoid it all <pause dur="0.8"/> but in the first two cases they actively preferred it <pause dur="0.4"/> suggesting that for some reason <pause dur="0.5"/> they learned that this <pause dur="0.2"/> food is a good thing <pause dur="0.3"/> when they'd experienced it on the nose and mouth <pause dur="0.3"/> of an awake or anaesthetized rat <pause dur="0.4"/> so what was it that was crucial <pause dur="0.6"/> Galef tried two other conditions <pause dur="0.4"/> for example he said what would happen <pause dur="0.5"/> if you <pause dur="0.4"/> expose the observer to the food not on the nose and mouth but on the back <pause dur="0.3"/> of a live rat <pause dur="0.7"/> and in that case they didn't learn a preference either <pause dur="0.9"/> what happens if you just put it on a neutral base like a roll of tissue <pause dur="0.3"/> then they didn't observe then they didn't find a preference <pause dur="1.1"/> what Galef found in the end after these series of experiments that the only thing that was crucial <pause dur="0.7"/> there didn't have to be a rat there at all <pause dur="0.7"/> but that the observer rat had to experience the smell of the rat <pause dur="0.3"/> mixed with the smell

of rat breath <pause dur="0.9"/> rat breath contains an unpleasant smelling chemical called carbon disulphide <pause dur="0.6"/> and what Galef found was that if he just exposed observer rats <pause dur="0.4"/> to the smell of food X plus the smell of carbon disulphide without any rat being there at all <pause dur="0.5"/> they would acquire just as much preference <pause dur="0.4"/> as if they'd smelled it on the face of a <trunc>wak</trunc> <pause dur="0.2"/> a waking rat <pause dur="2.2"/> what this implies is that there was no <pause dur="0.2"/> real <pause dur="0.2"/> social element to the learning in this case <pause dur="0.8"/> the observers had not learned to prefer <pause dur="0.3"/> the <pause dur="0.7"/> food X <pause dur="0.4"/> because of anything in the behaviour <pause dur="0.3"/> of the demonstrator rat <pause dur="0.6"/> but simply because if the demonstrator rat is alive <pause dur="0.5"/> that gives them the opportunity to smell it in the context of other rats' breath and this simple rule <pause dur="0.7"/> if you smell something <pause dur="0.3"/> in conjunction with a rat's breath it's good <pause dur="0.3"/> that's enough to produce <pause dur="0.2"/> this learned preference <pause dur="1.2"/> so <pause dur="1.0"/> this learning will normally take place in a social context <pause dur="0.3"/> other rats normally have to be around to generate the smell of rat breath <pause dur="0.4"/> unless an

experimenter comes along and fools you by presenting you with carbon disulphide <pause dur="0.3"/> generally speaking you'll experience rat breath <pause dur="0.3"/> with <pause dur="0.6"/> a live rat <pause dur="0.6"/> but what this series of experiments shows is that the presence of the live rat is not necessary for the learning <pause dur="0.7"/> so <pause dur="0.4"/> this kind of experiment helps us to refine our understanding <pause dur="0.6"/> of <pause dur="0.3"/> what <pause dur="0.2"/> actually goes on <pause dur="0.2"/> as opposed to what might go on <pause dur="0.7"/> and <pause dur="0.7"/> it's <pause dur="0.5"/> it's very interesting to see how <pause dur="0.8"/> in real life <pause dur="0.4"/> a perfectly simple form of learning <pause dur="0.3"/> is enough <pause dur="0.2"/> to produce <pause dur="0.3"/> the desired effect <pause dur="0.4"/> that rats will produce foods <pause dur="0.4"/> which other live <trunc>ra</trunc> that rats will prefer foods <pause dur="0.2"/> that other live rats have eaten <pause dur="5.5"/> the next kind of <pause dur="6.2"/><kinesic desc="changes transparency" iterated="y" dur="6"/> stimulus significance learning that i want to talk about <pause dur="0.3"/> is learning about predators <pause dur="0.7"/> clearly <pause dur="0.4"/> and i don't have time to go into this <pause dur="0.5"/> animals have many ways of signalling the presence of predators to each other like alarm calls <pause dur="0.5"/> it's very common for animals to learn <pause dur="0.3"/> what's dangerous <pause dur="0.4"/> in social situations <pause dur="1.0"/> and <pause dur="0.4"/> the experiments i want to describe now are a very <pause dur="0.5"/>

well known and elegant series of experiments by Susan Mineka <pause dur="1.7"/> about <pause dur="1.0"/> the way in which <pause dur="0.6"/> monkeys <pause dur="0.2"/> learn <pause dur="0.9"/> that snakes are dangerous <pause dur="4.5"/> in <pause dur="0.2"/> their natural environment <pause dur="0.6"/> these are monkeys these are macaques again <pause dur="0.4"/> who live in the Indian who live in India <pause dur="0.3"/> mostly in <pause dur="0.7"/> jungle or in areas surrounding towns where are there are a lot of snakes <pause dur="0.4"/> snakes are genuinely dangerous <pause dur="0.5"/> and <pause dur="0.3"/> wild-reared monkeys monkeys that have grown up in the wild are all frightened of snakes <pause dur="1.6"/> however <pause dur="0.7"/> if you take <pause dur="0.7"/> monkeys who've been reared in a lab <pause dur="0.8"/> have never lived in the normal environment and have never <pause dur="0.3"/> come into contact with snakes they are not afraid of snakes at all <pause dur="0.4"/> you can show them a <pause dur="0.2"/> picture of a snake or even a real snake <pause dur="0.4"/> they'll just treat it as a novel and slightly interesting object <pause dur="0.6"/> so it seems very plausible <pause dur="0.6"/> that monkeys in <pause dur="0.3"/> the in the <trunc>le</trunc> in the wild <pause dur="0.5"/> learn to fear snakes from other monkeys who've already acquired the fear <pause dur="1.1"/> and Mineka set up an experimental situation <pause dur="0.5"/> where <pause dur="0.3"/> observer monkeys <pause dur="0.3"/> could watch

who were of course naive and didn't fear snakes initially as you'll see <pause dur="0.6"/> could watch a demonstrator <pause dur="0.3"/> who previously had learned fear of snakes for example a wild-caught monkey <pause dur="0.5"/> and the question is <pause dur="0.2"/> what would the observers learn from the demonstrator <pause dur="1.8"/> # <pause dur="0.7"/> to explain the <pause dur="0.2"/> procedure before i show you the data <pause dur="0.6"/> the observers were tested three times <pause dur="0.3"/> first of all a pretest when they were still naive and they'd never seen a demonstrator acting afraid of snakes <pause dur="1.1"/>

a post-test immediately after they'd seen a demonstrator monkey acting afraid of snakes <pause dur="0.5"/> and then a follow-up three months later with no intervening training <pause dur="0.4"/> to see whether their <trunc>f</trunc> <pause dur="0.4"/> whether whatever they'd learned was persistent <pause dur="1.5"/> and the way the observers were tested was in a choice circus which was just a <pause dur="0.4"/> a round arena with four objects at the four corners <pause dur="0.3"/> one of which was a model snake <pause dur="0.6"/> and the other three were neutral objects <pause dur="0.5"/> and they simply measured <pause dur="0.3"/> how much time <pause dur="0.5"/> the observer monkey would spend <pause dur="0.2"/> near the snake <pause dur="0.5"/> if they were not frightened of snakes they'd spend about quarter of the time near the snake <pause dur="0.5"/> and a quarter of the time near the other objects <pause dur="0.4"/> if they were afraid of the snake they'd spend very little time near the snake <pause dur="0.3"/> and more much more time near the other objects so <pause dur="0.5"/> how much time they spend near the snake is one measure of fear <pause dur="1.0"/> the other measure of fear is that <pause dur="0.4"/> they used something called a Wisconsin test apparatus which is an apparatus simply where monkeys have to

reach over a gap to get food <pause dur="1.3"/> and <pause dur="0.4"/> if you put <pause dur="0.2"/> a frightening stimulus in a glass box in the gap <pause dur="0.5"/> the monkeys will be reluctant to reach over it to get the food <pause dur="0.5"/> so in this test they put <pause dur="0.4"/> a snake <pause dur="0.2"/> either real or live in the glass box <pause dur="0.5"/> and look to see how slow <pause dur="0.2"/> the observers were <pause dur="0.4"/> to reach over the <trunc>s</trunc> over the snake <pause dur="0.3"/> to get a tempting bit of food <pause dur="0.5"/> and the slower they were and the more disturbed their behaviour <pause dur="0.5"/> the more frightened they were concluded to be of snakes <pause dur="0.2"/> so the question is how did the observers' behaviour change <pause dur="0.5"/> as a function of watching the demonstrators <pause dur="9.6"/><kinesic desc="changes transparency" iterated="y" dur="4"/> the graph is slightly complicated perhaps i'll just stick to the top one <pause dur="0.5"/> which shows <pause dur="0.4"/> the time spent <pause dur="0.4"/> near the snake <pause dur="0.4"/> in the choice circus <pause dur="0.5"/> and remember <pause dur="0.5"/> an animal <pause dur="0.3"/> that is <pause dur="2.2"/> # <pause dur="0.4"/> very frightened of a snake <pause dur="0.5"/> will spend very little time near the snake <pause dur="0.3"/> and much more time near other stimuli that are not snakes <pause dur="0.7"/> now this first graph here <pause dur="0.6"/> is not the behaviour of <sic corr="the">be</sic> observer but the behaviour of the model <pause dur="0.7"/> it's the behaviour of the

monkey <pause dur="0.5"/> who really is frightened of snakes just to show you that if you really have a strong fear of snakes <pause dur="0.4"/> this is what you do <pause dur="0.6"/> in the <pause dur="0.3"/> choice <trunc>appara</trunc> in the choice <pause dur="0.2"/> circus <pause dur="0.6"/> mean time spent with each stimulus <pause dur="0.4"/> the stimuli are a real snake a toy snake <pause dur="0.3"/> a model snake and a neutral stimulus <pause dur="0.7"/> and you can see that the <pause dur="0.6"/> the monkey who really is frightened of snakes <pause dur="0.5"/> spends almost no time <pause dur="0.2"/> near <pause dur="0.3"/> either the real the toy or the model snake <pause dur="0.2"/> spends all its time near the neutral stimulus so that pattern <pause dur="0.3"/> indicates very strong fear of snakes <pause dur="1.0"/> what do the observers do <pause dur="0.6"/> okay here they are on the pretest when they're not afraid of snakes at all <pause dur="0.6"/> and as you can see they divide their time equally <pause dur="0.2"/> between the four stimuli they show no avoidance of snakes at all <pause dur="0.2"/> at the pretest <pause dur="1.2"/> but at the post-test when they've had an opportunity to watch an observer who is <pause dur="0.3"/> in the presence of a snake and acting frightened <pause dur="0.5"/> now they behave <pause dur="0.4"/> not as frightened as the model <pause dur="0.4"/> but very much more like the model

they spend a lot of time near the neutral stimulus <pause dur="0.3"/> and very little time <pause dur="0.2"/> near the snakes so they have acquired <pause dur="0.4"/> fear of snakes <pause dur="0.4"/> just by watching another monkey <pause dur="0.9"/> and this fear is just as strong <pause dur="0.2"/> at the three month follow-up <pause dur="0.4"/> as it was immediately after <pause dur="0.9"/> so this is evidence that <pause dur="0.6"/> naive rhesus monkeys who are not afraid of snakes to start with <pause dur="0.5"/> can learn that snakes are dangerous <pause dur="0.3"/> just by watching another monkey they don't have to be bitten by a snake or attacked by a snake or anything <pause dur="0.4"/> they can just learn it by watching another monkey <pause dur="3.8"/><kinesic desc="changes transparency" iterated="y" dur="7"/> there's another very interesting feature of this learning which i want to mention because it <pause dur="0.5"/> it allows me to link <pause dur="0.4"/> this phenomenon <pause dur="0.5"/> with another <pause dur="0.5"/> effect <pause dur="0.4"/> that i mentioned in my lecture a week ago <pause dur="0.6"/> you remember <pause dur="0.4"/> in my lecture a week ago i mentioned that <pause dur="0.4"/> contrary to what Pavlov thought <pause dur="1.2"/> associative learning is selective <pause dur="0.7"/> some <pause dur="1.0"/> pairs of stimuli if you like <pause dur="0.4"/> are easier to associate than others <pause dur="0.6"/> so <pause dur="0.6"/> tastes are easier to associate with sickness <pause dur="0.4"/> visual stimuli are

easier to associate with external pain <pause dur="0.2"/> in the case of rats <pause dur="0.2"/> there are many other examples <pause dur="0.5"/> now this <pause dur="0.6"/> observational learning of fear by monkeys <pause dur="0.4"/> turns out to be <pause dur="0.5"/> to have rather similar properties <pause dur="2.0"/> we've seen in the last experiment <pause dur="0.3"/> that <pause dur="2.0"/> monkeys can readily learn <pause dur="0.2"/> to be afraid of snakes <pause dur="0.5"/> by watching another monkey who shows fear of snakes <pause dur="0.9"/> but can they avoid <pause dur="0.3"/> can they learn to avoid other stimuli <pause dur="0.4"/> not snakes <pause dur="0.5"/> by watching <pause dur="0.4"/> an animal <pause dur="0.3"/> another monkey <pause dur="0.2"/> who's afraid of those other stimuli <pause dur="1.2"/> the problem is how can you induce <pause dur="0.2"/> a monkey to act <sic corr="afraid">fafraid</sic> of a harmless stimulus <pause dur="0.5"/> well for this purpose <pause dur="0.4"/> Mineka very cleverly just used a split screen video technique <pause dur="0.5"/> she made a video of a frightened monkey <pause dur="0.9"/> and at the bottom of the screen she showed either a picture of a snake <pause dur="0.5"/> or by splicing in another video <pause dur="0.4"/> a picture of a different stimulus which in her case was a bunch of flowers <pause dur="1.7"/> so the observers <pause dur="1.0"/> were in two groups <pause dur="0.6"/> one group of observers <pause dur="0.5"/> watched a video <pause dur="0.3"/> apparently showing a monkey who was frightened of

flowers <pause dur="0.2"/> but not frightened of snakes <pause dur="0.5"/> that's F-L-plus S-N-minus meaning <pause dur="0.6"/> this model <pause dur="0.5"/> monkey <pause dur="0.7"/> was afraid of flowers but not afraid of snakes <pause dur="0.7"/> the other group <pause dur="0.2"/> S-N-plus F-L-minus saw the opposite <pause dur="0.7"/> they saw a video of a monkey who acted frightened in the presence of the picture of a snake <pause dur="0.4"/> but not frightened in the presence of a picture of flowers <pause dur="0.5"/> and the question is <pause dur="0.9"/> would <pause dur="0.2"/> each of these groups <pause dur="0.2"/> learn to fear <pause dur="0.3"/> the stimulus that the model <pause dur="0.3"/> feared <pause dur="0.9"/> or <pause dur="0.2"/> as you might by now be expecting <pause dur="0.4"/> is there selectivity so that <pause dur="0.2"/> the observer monkeys <pause dur="0.4"/> can readily learn fear of snakes by watching a model <pause dur="0.5"/> but not readily learn fear of flowers <pause dur="0.4"/> and that's what happened <pause dur="1.0"/><kinesic desc="indicates point on transparency" iterated="n"/> over here is the group F-L-plus S-N-minus <pause dur="0.5"/> who watched <pause dur="0.4"/> a video of a monkey who was frightened of flowers but not frightened of snakes <pause dur="0.6"/> and you can see <pause dur="0.7"/> in terms of their reaction here again <pause dur="0.6"/><kinesic desc="indicates point on transparency" iterated="n"/> in this case <pause dur="0.3"/> slow responding indicates fear <pause dur="0.2"/> so i'm sorry this is the other way round from the last graph <pause dur="0.5"/> but <pause dur="0.5"/><kinesic desc="indicates point on transparency" iterated="n"/> this is the case where monkeys had to reach

over a snake to get food <pause dur="0.5"/> so if they're slow at reaching <pause dur="0.2"/> that's a long latency <pause dur="0.3"/> that means they're afraid of snakes <pause dur="0.8"/> so what you're looking for here is <pause dur="0.4"/> is there a long latency <pause dur="0.3"/> in the presence of real or toy snakes <pause dur="0.8"/> the black and white bars <pause dur="1.1"/> so here we see the group <pause dur="0.6"/><kinesic desc="indicates point on transparency" iterated="n"/> who had <pause dur="0.4"/> watched a video of a monkey who was frightened of flowers but not snakes <pause dur="0.4"/><kinesic desc="indicates point on transparency" iterated="n"/> here's prewatching the video and post-watching the video <pause dur="0.6"/> and you can see that <pause dur="0.3"/> first of all <pause dur="0.4"/> there's no change in the attitudes of these monkeys to flowers they haven't learned to fear flowers at all <pause dur="0.4"/> by watching another monkey being afraid of flowers <pause dur="0.5"/> if anything <pause dur="0.3"/> they've increased their fear of snakes a little bit <pause dur="0.6"/> even though the monkey they watched in the video was not frightened of snakes <pause dur="0.5"/> they've still <pause dur="0.3"/> somehow <pause dur="0.5"/> # presumably by stimulus generalization linked the two <pause dur="1.3"/> the other group were completely different the group who've watched a monkey frightened of snakes but not frightened of flowers <pause dur="0.3"/> show a big increase in fear

of snakes <pause dur="0.7"/> high <pause dur="0.3"/> latencies for snakes <pause dur="0.7"/> so <pause dur="0.5"/> this kind of <pause dur="0.9"/> associative learning <pause dur="0.5"/> observational learning <pause dur="0.4"/> also can show stimulus selectivity <pause dur="0.4"/> and i don't think you need me to tell you little stories to understand why that <pause dur="0.2"/> might be <pause dur="0.4"/> advantageous <pause dur="0.6"/> because snakes are a genuine predator <pause dur="0.5"/> therefore <pause dur="0.3"/> monkeys who can rapidly and efficiently learn fear of snakes <pause dur="0.3"/> from a small amount of exposure to a frightened conspecific <pause dur="0.5"/> are the ones who are likely to survive if they meet an actual snake <pause dur="1.1"/> so <pause dur="1.2"/> i just wanted to show you that example not only because it's a very elegant experiment <pause dur="0.4"/> which has also of course <pause dur="0.6"/> been used to cast light on <pause dur="0.7"/> # <pause dur="0.7"/> some of the <pause dur="0.6"/> fears both learned and unlearned that humans show because of course as you know snake fears are extremely common in humans <pause dur="0.4"/> even humans who've never met a snake in their life <pause dur="0.7"/> so Mineka's experiments have been used to discuss the possible biological basis of snake phobia <pause dur="3.5"/> but <pause dur="0.4"/> # <pause dur="0.3"/> i think <trunc>th</trunc> # but i also wanted to make the point <pause dur="0.4"/> that there is <pause dur="0.3"/> associative

selectivity in that as well as in other cases <pause dur="4.6"/><kinesic desc="changes transparency" iterated="y" dur="4"/> the second kind of learning i want to discuss is the learning of new behaviours <pause dur="0.8"/> so far we've seen examples where animals <pause dur="0.3"/> learn something about the significance of stimuli <pause dur="0.6"/> in the food case <pause dur="0.4"/> they learned that food was okay <pause dur="0.2"/> but through a rather simple mechanism <pause dur="0.9"/> in the <pause dur="0.6"/> snake case they learned that snakes were dangerous <pause dur="0.3"/> <trunc>ra</trunc> in a rather specific way through watching other monkeys <pause dur="1.3"/> the next question is <pause dur="0.3"/> can animals learn <pause dur="0.3"/> complex new behaviours <pause dur="0.5"/> by watching others <pause dur="0.4"/> like <pause dur="0.4"/> the question <pause dur="0.3"/> can young black rats <pause dur="0.3"/> learn <pause dur="0.4"/> how to <pause dur="0.7"/> gnaw efficiently at a pine cone <pause dur="0.4"/> by watching their mothers <pause dur="5.8"/><kinesic desc="changes transparency" iterated="y" dur="11"/> well experiments <pause dur="0.5"/> on this topic <pause dur="0.6"/> have basically the following kind of design <pause dur="1.2"/> obviously you have <pause dur="0.7"/> one group <pause dur="0.7"/> let's call them the experimental observers <pause dur="0.5"/> who have the opportunity to watch a trained demonstrator who's already learned a particular action call it X <pause dur="0.8"/> and importantly <pause dur="0.3"/> gets rewarded <pause dur="0.2"/> for performing action X <pause dur="0.4"/> because clearly <pause dur="0.4"/> if observers are

going to learn <pause dur="0.6"/> that performing this action leads to good things like getting food out of a pine cone <pause dur="0.4"/> presumably they need to see <pause dur="0.3"/> the demonstrator <pause dur="0.3"/> actually getting <pause dur="0.2"/> food <pause dur="0.6"/> for performing the action <pause dur="2.5"/> and in the test <pause dur="0.4"/> the observers are put on their own without the demonstrator and the question is how good are they <pause dur="0.3"/> at performing action X or perhaps how quick are they <pause dur="0.3"/> to learn it by themselves <pause dur="1.0"/> we need a control group to compare this group to <pause dur="0.3"/> various kinds of control groups are possible <pause dur="0.7"/> you might have control who watch a completely untrained demonstrator who doesn't perform action X at all <pause dur="1.3"/> you might watch nothing at all <pause dur="0.8"/> a better control <pause dur="0.5"/> is to watch trained demonstrators perform action X but not get any reinforcement for it <pause dur="0.2"/> that's much a much better balanced control <pause dur="1.8"/>

and if you find that it's the <trunc>expe</trunc> the experimental observers <pause dur="0.4"/> perform X more <pause dur="0.4"/> or acquire action X by themselves faster than the controls <pause dur="0.4"/> they must have learned something <pause dur="0.3"/> from watching <pause dur="0.5"/> the demonstrators <pause dur="2.0"/><kinesic desc="changes transparency" iterated="y" dur="4"/> here's a simple example <pause dur="0.3"/> of such evidence <pause dur="4.9"/> this is an example that i took from Pierce's book <pause dur="1.1"/> # <pause dur="2.5"/> group E are the experimental observers who watch they're rats and they watched another rat performing action X which is pressing a lever <pause dur="0.3"/> and getting food <pause dur="1.0"/> there are two control groups <pause dur="0.2"/> control group one <pause dur="0.2"/> watch nothing at all they just watch an empty chamber so that's what i described as not a very good control group <pause dur="1.1"/> control group two <pause dur="0.6"/> experienced what i described as a good control procedure <pause dur="0.4"/> where they observed another rat pressing the lever so they saw the action <pause dur="0.4"/> but the action did not result in food <pause dur="1.1"/> finally all three groups of observers <pause dur="0.3"/> were put in the box on their own <pause dur="0.5"/> and allowed to press the lever for three days <pause dur="0.4"/> and in this case lever pressing did produce food so they

had the opposite # the opportunity to learn for themselves that lever pressing produced food <pause dur="0.5"/> after watching <pause dur="0.2"/> these three <pause dur="0.3"/> possible demonstrations <pause dur="1.1"/> here's group E <pause dur="0.4"/> who <pause dur="0.3"/> had watched another rat pressing the lever and getting food <pause dur="0.5"/> and as you can see group E <pause dur="0.4"/> pressed the lever much more than the other <trunc>con</trunc> than either control group not only in the first session <pause dur="0.4"/> but they learned much faster as well <pause dur="0.9"/> so clearly <pause dur="0.3"/> group E <pause dur="0.2"/> had learned something <pause dur="0.2"/> from watching the other rat <pause dur="0.2"/> pressing the lever and getting food <pause dur="1.3"/> and <pause dur="1.1"/> what they'd learned was something <pause dur="0.2"/> different from what the controls <trunc>grou</trunc> <pause dur="0.2"/> from what the control groups might have gained <pause dur="0.2"/> from their experience <pause dur="0.4"/> it's interesting to notice by the way that the two control groups are very similar <pause dur="0.7"/> watching another rat pressing a lever and getting nothing <pause dur="0.5"/> really doesn't help you to learn <pause dur="0.3"/> any more <pause dur="0.4"/> than control one who watch an empty chamber <pause dur="0.3"/> so clearly watching the rat getting food and <pause dur="0.3"/> get <trunc>wo</trunc> pressing lever and getting food for it is quite crucial <pause dur="10.7"/><kinesic desc="changes transparency" iterated="y" dur="12"/>

now <pause dur="0.5"/> once again <pause dur="0.7"/> something is being learned <pause dur="1.4"/> but we can raise the question what is being learned <pause dur="0.3"/> how sophisticated <pause dur="0.4"/> is the learning that's going on <pause dur="1.3"/> when <pause dur="0.2"/> the rats in the experiment i've just described <pause dur="0.7"/> are better at learning to press a lever for food <pause dur="0.2"/> when they've watched another rat press a lever for food <pause dur="0.4"/> what might be going on <pause dur="0.6"/> and Galef again <pause dur="0.2"/> who has been <trunc>extreme</trunc> one of the most influential researchers in this field <pause dur="0.8"/> set out some possible ways in which <pause dur="0.3"/> the experimental observers might have learned <pause dur="1.6"/> one very simple one <pause dur="0.2"/> which is <pause dur="0.5"/> # <pause dur="0.5"/> perhaps <pause dur="1.6"/> rather like a very simple explanation that i offered for the young black rats learning about pine cones <pause dur="0.4"/> is what Galef called local stimulus enhancement <pause dur="0.7"/> what he meant by that is this <pause dur="0.8"/> perhaps <pause dur="0.2"/> what the experimental observers learn <pause dur="0.6"/> when they watch <pause dur="0.7"/> the demonstrators <pause dur="0.3"/> perform action X and get food <pause dur="0.6"/> is that <pause dur="2.6"/> it's a good idea to be near that lever <pause dur="1.3"/> that because another rat is near the lever <pause dur="0.4"/> they get interested in the lever <pause dur="0.5"/> so when they're allowed to

try it out on their own <pause dur="0.3"/> they spend more time near the lever <pause dur="0.3"/> and as a result they learn by the sort of processes i described in yesterday's lecture <pause dur="0.4"/> how to press the lever for themselves <pause dur="1.3"/> now <pause dur="0.6"/> you should immediately be able to see that that cannot explain the results of the experiments i've just shown you <pause dur="0.4"/> 'cause if that were what was going on <pause dur="0.4"/> you should have got just as much enhancement of learning <pause dur="0.5"/> in <pause dur="0.5"/> control group two <pause dur="1.6"/> who watched another rat press the lever <pause dur="0.3"/> and get nothing <pause dur="0.5"/> after all control group two had watched another rat pressing the lever <pause dur="0.5"/> so if it was just <pause dur="0.3"/> local enhancement getting attracted to that area of the box <pause dur="0.5"/> then <pause dur="0.3"/> control group two should show just as much lever pressing but they don't <pause dur="0.7"/> so clearly <pause dur="0.9"/> local enhancement as Galef called it <pause dur="0.3"/> while it's <pause dur="0.5"/> logically possible <pause dur="0.5"/> can't explain that example <pause dur="1.0"/> however <pause dur="0.6"/> what about the second possibility what Galef called blind imitation <pause dur="0.6"/> which means just copying what another animal does <pause dur="0.5"/> but not being aware of the

consequences <pause dur="1.1"/> # <pause dur="0.5"/> you might say this is rather like <pause dur="0.5"/> kids who smoke <pause dur="0.6"/> because other kids smoke <pause dur="0.4"/> but don't actually care whether it makes them feel sick makes them ill later or whatever <pause dur="0.4"/> blind imitation <pause dur="0.2"/> without being aware of the consequences <pause dur="0.5"/> well once again this won't explain that example <pause dur="0.6"/> because otherwise again <pause dur="0.3"/> control group two who performed <pause dur="0.4"/> lever pressing without reinforcement <pause dur="0.3"/> should be likely to elicit blind imitation <pause dur="0.7"/> so that's not likely to apply here <pause dur="0.5"/> but one that certainly could be going on <pause dur="0.5"/> is what Galef called observational conditioning <pause dur="1.3"/> which is that what might be happening is not <pause dur="0.6"/> learning to associate the action of lever pressing with food <pause dur="0.3"/> but just learning to associate the lever with food <pause dur="0.7"/> perhaps <pause dur="0.3"/> the animals in <pause dur="0.4"/> the experimental group <pause dur="3.0"/> learn <pause dur="1.0"/> that <pause dur="0.7"/> every time they look at the lever <pause dur="0.2"/> because they're watching the rat <pause dur="0.2"/> food is delivered <pause dur="0.3"/> so they associate the sight of the lever with food <pause dur="0.5"/> whereas of course the other groups <pause dur="0.2"/> do not associate the sight of the lever with

food <pause dur="0.7"/> it may not be <pause dur="0.3"/> learning the action of pressing the lever <pause dur="0.3"/> it may just be learning that that lever is a good thing it's associated with food <pause dur="0.5"/> and you all know what happens <pause dur="0.2"/> if you give that kind of Pavlovian training to rats <pause dur="0.4"/> if they learn to associate a particular object such as a lever with food what do they do <pause dur="0.3"/> they rush over to it <pause dur="0.3"/> they touch it <pause dur="0.2"/> they nose it <pause dur="0.4"/> and they're very likely to press it in the process <pause dur="0.4"/> get food for it <pause dur="0.4"/> and so this purely Pavlovian learning <pause dur="0.4"/> may <pause dur="0.2"/> set the scene <pause dur="0.2"/> for instrumental learning <pause dur="0.5"/> so this example could very well be <pause dur="0.5"/> what Galef called observational conditioning <pause dur="0.7"/> rather than what he called true observational learning <pause dur="0.5"/> I-E learning <pause dur="0.2"/> not just that the lever is good but you've got to press the lever to get food <pause dur="0.4"/> that's what Galef called true observational learning <pause dur="0.8"/> so <pause dur="0.6"/> how can one <pause dur="0.3"/> experimentally <pause dur="0.5"/> analyse <pause dur="0.5"/> which of these things is going on <pause dur="0.2"/> i've argued that not all of them could be going on <pause dur="0.3"/> in the rat case <pause dur="0.4"/><kinesic desc="changes transparency" iterated="y" dur="13"/> but certainly <pause dur="0.2"/> more than one of them could <pause dur="4.4"/> a very

neat experiment <pause dur="0.3"/> to try and <pause dur="0.6"/> sort out these possibilities <pause dur="0.9"/> is this one <pause dur="0.9"/> by Palameta and Lefebvre who were French Canadians which explains their <pause dur="0.5"/> # slightly unusual names <pause dur="0.6"/> still are French Canadians in fact as far as i know <pause dur="1.1"/> # <pause dur="3.6"/> in their case this was an experiment with pigeons <pause dur="0.9"/> they had <pause dur="1.6"/> untrained pigeon observers <pause dur="0.7"/> who observed trained pigeons <pause dur="0.5"/> performing a particular action <pause dur="0.6"/> under a number of different conditions <pause dur="0.6"/> the action was this <pause dur="0.8"/> the <pause dur="0.3"/> model pigeons were in a box which contained two bits of paper <pause dur="0.3"/> a red paper <pause dur="0.2"/> and a black paper <pause dur="2.0"/> underneath the red paper <pause dur="0.4"/> there was a bowl of food <pause dur="0.6"/> underneath the black paper <pause dur="0.2"/> there was nothing <pause dur="4.2"/> it was easy to train <pause dur="0.3"/> model pigeons <pause dur="0.4"/> to perform a particular action <pause dur="0.9"/> piercing the red paper with their beak <pause dur="0.5"/> to get through it to get the food from underneath <pause dur="0.9"/> so <pause dur="1.3"/> the true observational learning group <pause dur="0.2"/> of observers <pause dur="0.3"/> watched precisely that <pause dur="0.5"/> they watched <pause dur="0.3"/> a demonstrator pigeon <pause dur="0.3"/> perform the action <pause dur="0.3"/> of piercing with its beak <pause dur="0.8"/> directed at the red paper not the black paper <pause dur="0.4"/> and they

observed it getting food as a result <pause dur="1.1"/> so <pause dur="0.5"/> if <pause dur="0.5"/> true observational learning is possible <pause dur="0.4"/> it should be particularly good in that group <pause dur="1.8"/> the other groups were given <pause dur="0.4"/> experience that might be expected to produce either blind imitation <pause dur="0.4"/> or local enhancement and the question is how much <pause dur="0.4"/> improvement <pause dur="0.2"/> in the behaviour would they show <pause dur="0.7"/> first of all what did the groups have well <pause dur="0.4"/> the naive group were just a control group who never watched a model anyway so they're just the baseline the controls <pause dur="0.7"/> the blind imitation group <pause dur="0.5"/> watched a trained demonstrator pierce the red paper but not get any food <pause dur="1.1"/> so if the only learning that was going on was blind imitation just do the same thing as the demonstrator <pause dur="0.6"/> that group should learn just as much as the observational learning group did <pause dur="0.9"/> if those groups were equal <pause dur="0.2"/> it would suggest that the learning was blind imitation <pause dur="0.5"/> but if the observational learning group were better than the blind imitation group <pause dur="0.3"/> it would suggest that learning was more than just blind imitation <pause dur="0.4"/>

that it involved learning this action leads to food <pause dur="1.3"/> the local enhancement group and this was quite cunning <pause dur="0.7"/> they saw the red paper <pause dur="0.6"/> and they saw the demonstrator put the head through the red paper and get food <pause dur="0.5"/> but because there was already a hole cut in the paper the demonstrator didn't actually have to perform the action of piercing <pause dur="1.6"/> so that group would see <pause dur="0.6"/> what should produce local enhancement or observational conditioning <pause dur="0.5"/> that this red paper is good <pause dur="0.5"/> 'cause the pigeon goes near it <pause dur="0.4"/> and it's associated with food <pause dur="0.4"/> so if that's the basis of the learning <pause dur="0.5"/> it should be just as good in these two groups <pause dur="0.8"/> so the argument is that <trunc>th</trunc> there was another pair of groups which were tested after a delay but i won't waste time with them <pause dur="0.8"/> so by looking <pause dur="0.5"/> so <pause dur="0.2"/> subsequently <pause dur="0.6"/> the <pause dur="0.3"/> observers <pause dur="0.7"/> were <pause dur="0.3"/> put in the apparatus <pause dur="0.5"/> and Palameta and Lefebvre <pause dur="0.3"/> measured <pause dur="0.5"/> how much tendency they showed how quickly they learned <pause dur="0.3"/> to perform the action of piercing the red paper <pause dur="0.2"/> themselves <pause dur="0.6"/> and the argument was if the true

observational learning group was best <pause dur="0.5"/> that suggests that more is going on than just local enhancement or blind imitation <pause dur="0.6"/> but if either of these two groups is as good as the <trunc>loc</trunc> the observational learning group <pause dur="0.4"/> that suggests that <pause dur="0.3"/> the learning can be explained <pause dur="0.4"/> by local enhancement or blind imitation <pause dur="0.3"/> and does not require <pause dur="0.4"/> the full <pause dur="0.5"/> panoply <pause dur="0.2"/> if you like <pause dur="0.9"/> shouldn't use this word with <gap reason="name" extent="1 word"/> here <vocal desc="laugh" iterated="n"/> he's testing out what language i use in my lecture you see i just realized that's a rather rare word <pause dur="0.2"/> anyway <pause dur="0.4"/> so <pause dur="0.5"/> if <pause dur="0.6"/> # <pause dur="0.5"/> pigeons who were <pause dur="1.3"/> learning the full <pause dur="0.2"/> experience if you like <pause dur="0.2"/> that <pause dur="0.2"/> this action is needed <pause dur="0.5"/> to get this food <pause dur="0.9"/> then <pause dur="0.7"/> only the observational learning group <pause dur="0.3"/> should <pause dur="0.4"/> be able to learn that <pause dur="0.2"/> and they should be best <kinesic desc="changes transparency" iterated="y" dur="7"/> okay so what happened after all that <pause dur="4.8"/> forget the delayed groups we can just forget about them <pause dur="0.4"/> these are the four groups <pause dur="1.3"/> this is <pause dur="0.4"/> the true observational learning group who watched the model piercing <pause dur="0.3"/> the red paper and getting food <pause dur="0.9"/>

this is their <pause dur="0.3"/> the latency of the observers <pause dur="0.2"/> to peck themselves over a series of trials <pause dur="0.3"/> these are like Thorndike's graphs showing <pause dur="0.4"/> the latency of responding getting faster and faster shorter and shorter <pause dur="0.4"/> as animals learn <pause dur="0.7"/> and you can see that that group <pause dur="0.5"/> really did learn fairly rapidly they took time on the first trial they weren't that wonderful they hadn't learned straight off <pause dur="0.5"/> but they fairly rapidly over a series of ten trials <pause dur="0.3"/> learned for themselves to perform the action <pause dur="0.6"/> none of the other groups was as good <pause dur="0.7"/> the group that was <pause dur="0.6"/> a little bit better than <pause dur="0.3"/> baseline <pause dur="0.3"/> was the local enhancement group suggesting that just local enhancement just learning that red paper is associated with food <pause dur="0.5"/> does produce some <pause dur="0.5"/> improvement <pause dur="0.4"/> so there is an element of local enhancement in this learning <pause dur="0.4"/> but much more of it is observational learning <pause dur="0.3"/> true observational learning <pause dur="0.4"/> the blind imitation group got nowhere <pause dur="0.3"/> suggesting that blind imitation just doesn't happen <pause dur="0.5"/> in this set-up <pause dur="1.2"/> and <pause dur="0.9"/> notice that these results are different

from the results with the rats pressing levers there's no reason why the same learning mechanism should apply <pause dur="0.3"/> to pigeons learning to pierce a red paper for food <pause dur="0.3"/> and to rats learning to press a lever for food <pause dur="0.3"/> you have to do these experiments separately <pause dur="0.3"/> for each situation <pause dur="0.4"/> if you really want to know what's going on <pause dur="0.4"/> but the nice thing about this experiment <pause dur="0.4"/> is that it does demonstrate <pause dur="0.2"/> learning <pause dur="0.3"/> that an action leads to food <pause dur="0.5"/> and it rules out most of the simpler explanations except <pause dur="0.4"/> a very small element <pause dur="0.3"/> of local enhancement <pause dur="6.3"/><kinesic desc="changes transparency" iterated="y" dur="5"/> finally then <pause dur="0.7"/> # <pause dur="0.8"/> i don't have time to discuss all these cases but <pause dur="0.5"/> these are the conclusions i'd like to draw <pause dur="0.9"/> # <pause dur="0.3"/> we've seen from the lab studies that you can demonstrate these various types of observational learning <pause dur="0.6"/> but <pause dur="0.3"/> the underlying processes may not be obvious <pause dur="0.3"/> and they may often be much simpler than one would like to believe <pause dur="0.4"/> we're anthropomorphic <pause dur="0.4"/> we tend to believe that things go on in animals' heads <pause dur="0.2"/> similar to what would go on

in our heads when we're watching <pause dur="0.6"/> we think that if your mother shows you how to boil an egg <pause dur="0.2"/> you learn all about how to boil an egg <pause dur="0.3"/> and rats ought to be like that <pause dur="0.4"/> when they watch their mother <pause dur="0.2"/> <trunc>chew</trunc> chewing a pine cone <pause dur="0.3"/> they learn everything their mother knows that just isn't true <pause dur="1.0"/> animals' social learning is often a lot simpler <pause dur="0.5"/> than it would be in our case <pause dur="1.1"/> forget about the diving rats i'll leave that out because i haven't talked about it <pause dur="0.7"/> # <pause dur="0.7"/> i would like to talk finally very briefly about the famous primate examples <pause dur="0.7"/> you remember <pause dur="0.4"/> the case of chimps <pause dur="0.4"/> fishing <pause dur="0.3"/> for termites in a termite mound by putting in a twig <pause dur="0.5"/> and you remember the case of the macaques who washed food <pause dur="1.5"/> to what extent can we conclude <pause dur="0.4"/> that <pause dur="0.2"/> observational learning was responsible <pause dur="0.7"/> well in the case of termite fishing <pause dur="0.4"/> there's no doubt that young <pause dur="0.2"/> chimps <pause dur="0.4"/> intently watch their mothers <pause dur="0.2"/> when termite fishing <pause dur="0.7"/> and after watching their mothers <pause dur="0.5"/> they will often <pause dur="0.4"/> make a clumsy attempt to imitate <pause dur="0.4"/> they might get a twig <pause dur="0.4"/> they

might wave it in the direction of the termite mound <pause dur="0.4"/> but just from watching their mothers they do not get skilled at it <pause dur="0.7"/> they <pause dur="0.3"/> do not learn from their mothers how to strip the twig they don't learn how to poke it in <pause dur="0.3"/> in a very stealthy way so that the termites will <pause dur="0.4"/> climb onto it without being <trunc>ditu</trunc> disturbed <pause dur="0.4"/> they don't learn the whole skill from watching their mothers <pause dur="0.5"/> after they've watched their mothers there is a long process of individual <pause dur="0.7"/> learning <pause dur="0.6"/> without necessarily another animal being around <pause dur="0.5"/> so they learn a little bit from observation but they don't learn the whole skill <pause dur="1.8"/> what about food washing <pause dur="0.8"/> well again <pause dur="0.2"/> there's been <pause dur="0.4"/> a lot of speculation about this example but i just want to show you <pause dur="0.9"/> i want to tell you two things about this finally <pause dur="1.0"/> the first is <pause dur="0.2"/><kinesic desc="changes transparency" iterated="y" dur="2"/> this graph here <pause dur="0.2"/> which comes from Shettleworth's book which is pretty simple <pause dur="3.1"/> this shows <pause dur="0.9"/> observation of this colony where you remember <pause dur="0.5"/> the behaviour of washing <trunc>pot</trunc> sweet potatoes spread through the colony <pause dur="0.8"/> this shows over a

series of years <pause dur="0.7"/> the number of monkeys in the colony <pause dur="0.5"/> who were either <trunc>o</trunc> observed <pause dur="0.2"/> never to wash potatoes and as you can see there were quite a lot of those <pause dur="0.9"/> the number who were observed to wash potatoes starting with just one in nineteen-fifty-three <pause dur="0.5"/> and increasing to about fifteen by nineteen-fifty-eight <pause dur="0.7"/> and also a few who were in the process of learning to wash <pause dur="0.5"/> now what can we learn from a graph like this <pause dur="0.8"/> this line <pause dur="0.4"/> the number who actually wash potatoes goes up really quite slowly <pause dur="0.3"/> goes up from one to fifteen in five years <pause dur="0.7"/> so if this is observational learning it's very very slow <pause dur="1.6"/> the other thing is to look at the shape of this graph <pause dur="0.5"/> it goes up sort of steadily <pause dur="0.9"/> now if observational learning were really important <pause dur="0.5"/> you'd think that <pause dur="0.6"/> the more animals had learned it <pause dur="0.7"/> the more new animals would have the opportunity to learn <pause dur="0.7"/> 'cause if there's only one monkey who shows this behaviour <pause dur="0.3"/> it's going to be very rare for other animals to have the opportunity to watch her <pause dur="0.2"/> and

very few will learn <pause dur="0.3"/> it was by the way a female <pause dur="0.5"/> who was a young female who was number one <pause dur="1.4"/> # <pause dur="0.3"/> but the more animals who were doing it you'd think the more opportunity <pause dur="0.3"/> other animals had to observe it happening so you'd think that this graph ought to go up more and more steeply <pause dur="0.4"/> whereas in fact it goes up rather slowly <pause dur="0.6"/> and Shettleworth argues that this kind of graph <pause dur="0.6"/> is much more suggestive <pause dur="0.6"/> of <pause dur="0.7"/> individual monkeys learning <pause dur="0.6"/> independently <pause dur="0.4"/> by personal by individual learning <pause dur="0.2"/> to do it <pause dur="0.4"/> rather than watching other animals <pause dur="0.3"/> one would like to believe that they do it by watching other animals <pause dur="0.4"/> but this kind of data is really not very compatible with that hypothesis <pause dur="0.4"/> it's much more compatible with individual learning <pause dur="0.4"/> individuals learning <pause dur="0.4"/> that oh this sweet potato tastes nicer if you put it in the water <pause dur="0.4"/> or maybe there was some local enhancement <pause dur="0.4"/> maybe they followed other monkeys to the water <pause dur="0.6"/> and thus had a better chance to learn themselves <pause dur="1.6"/> the other sad story <pause dur="0.2"/> about the monkeys <pause dur="0.2"/> on <pause dur="0.6"/> # Kashima

Island <pause dur="0.7"/> is that it turned out later <pause dur="0.6"/> that you remember i've said that they were artificially provisioned <pause dur="0.2"/> they were fed by humans <pause dur="0.5"/> it turned out later <pause dur="0.4"/> that the humans who fed the monkeys were so charmed by this behaviour that they started training the monkeys to do it <pause dur="1.1"/> without the scientists knowing about it at first <pause dur="0.7"/> and in fact <pause dur="0.6"/> quite a lot of this <pause dur="0.2"/> increase <pause dur="0.3"/> could have been due <pause dur="0.3"/> to artificial training by humans <pause dur="0.3"/> rather than by the monkeys teaching each other <pause dur="0.6"/> now i <pause dur="0.2"/> i <trunc>d</trunc> i mean i'm ending these lectures on a note of scepticism i don't want you know to feel that there's nothing interesting to know about social learning in the wild there clearly is <pause dur="0.5"/> but the point i'm trying to make is that <pause dur="0.5"/> before jumping to the conclusion <pause dur="0.4"/> that some complex process is going on <pause dur="0.4"/> you really need to look a lot more closely <pause dur="0.6"/> at the experimental and behavioural evidence <pause dur="2.2"/> thank you