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Identifying the Role of Conscious Perception: a Neuroimaging and Computational Investigation

Primary Supervisor: Professor Howard Bowman, School of Psychology

Secondary supervisors: Dr Damian Cruse

PhD project title: Identifying the Role of Conscious Perception: a Neuroimaging and Computational Investigation

University of Registration: University of Birmingham

Project outline:

The question of what conscious perception is for remains a key, largely unanswered, question for the scientific study of consciousness and indeed for our whole understanding of mind. In fact, a substantial part of the scientific study of consciousness has focused on showing how sophisticated subconscious processing can be, seemingly leaving little room for a “special” purpose for conscious experience.

We have recently presented empirical evidence, which suggests that the subconscious brain is limited in its capacity to represent episodic information (Avilés, Bowman & Wyble, 2020; Bowman, Filetti, Alsufyani, Janssen & Su, 2014). By episodic, we are particularly emphasizing the capacity to associate percepts with the passage of time, something that we humans do so easily consciously that we hardly notice it. This work uses Rapid Serial Visual Presentation (RSVP) to present stimuli on the fringe of awareness. In Avilés, Bowman & Wyble (2020), we showed that the capacity to consciously perceive a stimulus does not benefit from repeating it unless it has been consciously perceived previously. Repetition is a key episodic property, i.e. to know that a presentation of a stimulus is a repetition, the brain has to have a memory of a previous episode of experiencing the stimulus. Additionally, if the RSVP stream of stimuli is slowed down sufficiently that the viewer consciously observes every stimulus, it becomes trivially easy to perform the task of detecting the repeating item.

The strong claim, then, is that a specific capacity provided by conscious perception is to lay down freely-recallable episodic memories of previous experiences. We now have extensive behavioural evidence for this hypothesis, a good deal of which will shortly appear in print. We are thus at a perfect stage to 1) characterise the neural correlates that support this formation of freely-recallable episodic memories, and 2) explain these findings with the computational theory that underlies our work in this area: the Simultaneous Type/ Serial Token model (Bowman & Wyble, 2007). Accordingly, we are proposing a PhD to work on one or both of these topics.

The first of these research activities, characterising neural correlates, could employ fMRI, MEG or EEG (all of which are available to us), with the latter two being particularly relevant because of their high temporal resolution. This line of research could take our existing RSVP behavioural paradigms and seek to identify neural components that are engaged when a stimulus presentation leads to the later detection of a repetition. This would give a new way to identify the neural components that are specific to conscious processing, with relevance to debates concerning whether the neural correlates of conscious processing reside in the sensory processing pathways or at a later, brain-scale, stage. Oscillatory correlates of conscious processing and episodic memory formation are of particular interest (Parish, Hanslmayr & Bowman, 2018).

The second research activity, computational modelling, would involve simulating the repetition effects and resulting correlates of conscious processing, with the Simultaneous Type/ Serial Token – a well attested theory of temporal attention and episodic encoding into working-memory (Bowman & Wyble, 2007). This neural network model is consistent with brain-scale state theories of conscious perception, such as the global workspace.

References:

  1. Avilés, Bowman & Wyble (2020). On the limits of evidence accumulation of the preconscious percept. Cognition, 195.
  2. Bowman & Wyble (2007). The simultaneous type, serial token model of temporal attention and working memory. Psychological review, 114(1), 38.
  3. Bowman et al. (2014). Countering countermeasures: detecting identity lies by detecting conscious breakthrough. PloS one, 9(3).
  4. Parish, Hanslmayr & Bowman (2018). The sync/desync model: How a synchronized hippocampus and a desynchronized neocortex code memories. Journal of Neuroscience, 38(14), 3428-3440.

BBSRC Strategic Research Priority: Understanding the Rules of Life: Neuroscience and behaviour

Techniques that will be undertaken during the project:

  • Neuroimaging – fMRI, electroencephalography, magnetoencephalography – both collection of data and its analysis.
  • Neural network modelling.
  • Designing and conducting behavioural experiments in Cognitive Psychology and Cognitive Neuroscience.
  • Advanced statistical and analysis techniques, including machine learning.

Contact: Professor Howard Bowman,University of Birmingham