About the Project
Dr Soren K Andersen (University of Aberdeen)
Dr Ramakrishna Chakravarthi (University of Aberdeen)
Recent research suggests that the human attentional system samples sensory information in roughly 7-8 discrete ‘snapshots’ per second in order to perceive the environment and guide behaviour (VanRullen, Carlson, & Cavanagh, 2007). This theory of ‘rhythmic attentional sampling’ thus counterintuitively posits that a cognitive process that inherently processes sensory input in discrete steps lies between the continuous flow of time in the external world and our temporally continuous subjective experience of it. This rhythmic attentional sampling may have evolved from rhythmic overt sampling behaviours observed across many species and sensory systems (e.g. saccades in vision, sniffs in olfaction, whisker movements in rat somatosensation).
Although multiple studies over the past decade have provided evidence towards this theory, both the strength and generalisability of this evidence is limited. Studies have generally employed tasks that emphasize detection of faint and brief near-threshold sensory events (e.g. Landau & Fries, 2012) and much of the evidence is either indirect (e.g. modelling based on hard to assess assumptions; VanRullen et al., 2007) or stems from rather exploratory approaches. Despite the fundamental challenges this theory poses to our understanding of how sensory information is utilised for perception and action, alternative accounts can therefore not be ruled out with sufficient certainty. For example, the observed temporal fluctuations in sensitivity to faint stimuli could be related to fluctuations of internal cortical noise rather than discrete sampling or they might represent small rhythmic fluctuations on top of fundamentally continuous processing.
This PhD project seeks to put to test the theory of rhythmic attentional sampling in experiments that specify strict criteria for falsification and employ above threshold stimuli. Several available experimental avenues may be combined based on applicant’s abilities and interests:
- Psychophysical experiments to test opposing predictions for reaction time variability in divided attention conditions for discrete vs. continuous sampling (e.g. Adamian, Slaustaite & Andersen, 2019)
- Direct measurement of attentional modulation of sensory processing using high-frequency steady-state visual evoked potentials in human EEG
- Quantitative modelling of behavioural performance in multiple-object tracking paradigms
The first and second supervisors are established experts in the use of above paradigms and techniques and provide tightly coordinated joint supervision. This project is embedded in the School of Psychology at the University of Aberdeen which provides a strong research environment and offers the opportunity to also benefit from the expertise of many active researchers in directly adjacent fields.
The PhD candidate involved in this project will have the opportunity to develop a thorough understanding of visual perception, visual selective attention, state-of-the-art electrophysiological and psychophysical techniques, experimental design practices, and statistical and quantitative modelling analysis techniques. This includes implementing paradigms and processing and analysing behavioural and EEG data in Matlab. Solid foundations in empirical research, strong analytical skills, mathematical aptitude, and coding experience would be highly regarded in applicants.
The project lies at the intersection of visual perception, cognitive psychology and human neuroscience and has a strong interdisciplinary character. It may thus suit candidates with backgrounds in psychology, neuroscience, behavioural biology, physics, or engineering.
Please send your completed EASTBIO application form, along with academic transcripts to Alison McLeod at firstname.lastname@example.org. Two references should be provided by the deadline using the EASTBIO reference form. Please advise your referees to return the reference form to email@example.com.
Candidates should have (or expect to achieve) a minimum of a 2:1 UK Honours degree, or the equivalent qualifications gained outside the UK, in a relevant subject.
- Landau AN & Fries P (2012). Attention samples stimuli rhythmically. Current Biology, 22, 1000–1004.
- VanRullen R, Carlson T & Cavanagh P (2007). The blinking spotlight of attention. Proceedings of the National Academy of Sciences USA, 104, 19204–19209.
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