Tim Gastrell

@tgastrell.bsky.social

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Cognition and Computation 🧠 Tech enjoyer 💻 🥝➡️🦘 PhD candidate in Cog/Comp Neuroscience at The University of Queensland 🧠 Studying how the brain leverages experience to support sensory processing and decision-making under uncertainty.

Neural tuning to motion direction expressed as decoding accuracy stratified by A) stimulus precision and B) prior precision during the observation and response periods (note the difference y-axis scales). Vertical red lines and grey dashed lines indicate coherent motion onset, and offset, respectively. Black solid, dashed and dotted lines indicate cluster significance p < .05 of pairwise condition comparisons. For the purposes of presentation, each trace was smoothed using a temporal Gaussian filter (sigma = 4). All statistical comparisons were performed on the unsmoothed data.
Behavioural results for Experiment 2 (EEG + Behaviour). A) Trial-level error histograms for each level of stimulus precision. B) Response accuracy stratified by stimulus precision and prior precision. C) Response bias stratified by stimulus precision and prior precision. Bias expressed as mean signed-error magnitudes such that attraction to the central-tendency of the current prior is captured by a positive shift in the error distribution. D) Bias stratified by stimulus precision and time within the session grouped into three equal-sized bins. Here, time reflects the exposure participants had to each of the priors. For visualisation, the data used to construct boxplots were normalised to remove the between subjects’ variability (Cousineau, 2005). Inset bar plots indicate t-statistics and significance of mixed GLM parameter estimates. * = p < .05.
Overview of the task and the manipulation of stimulus and prior precision. A) Structure of a single trial from pre-fixation to response. Note: trial diagram is schematic only, colours and scale differ from actual design (see Methods). B) Stimulus precision was manipulated via motion coherence, corresponding to the precision of the sampling distribution of possible dot-directions on each frame. Zero corresponds to the global target motion direction. C) Priors for motion direction were manipulated via the block-level sampling distribution for global target motion directions. These distributions could either be completely uninformative (uniform) or contain some information about the probability of upcoming stimulus values. In this case zero corresponds to the central tendency of the block-wise sampling distribution/prior.