Neuroscience Seminar Series: Rei Aikishi (Tokyo Metropolitan Institue of Medical Sciences): "What visual fixations reveal about evidence accumulation during decision making"
Wednesday, 08 July 2015, 1pm to 2pm
Schlich Lecture Theatre (Plant Sciences - see above for links for directions)
It is commonly said that the eyes are the windows to the soul. As this old statement indicates, eye movements are believed to reflect internal mental processes such as decision making. However, because eye-movements have been used to make decisions in many previous studies, particularly for electrophysiological recordings, it remained ambiguous whether their observed “decision signal” was in fact effector-specific pre-motor activity or reflected a more general signal such as saliency. Through examination of visual fixation patterns during decision making, I propose that the decision process can be interpreted as accumulation of a general signal toward the target of the chosen action. More specifically, using a novel decision making task with free eye-movement and manual responses based on multiple cues, I will show that the frequency of visual fixations of monkey subjects on chosen targets exhibited a pattern reflective of a general information accumulation process. Furthermore, contrary to the common assumption that the information provided by multiple cues are equally weighted and directly fed into the accumulation process, the fixation data are best explained by the computational model with cue selector stage, i.e. a model which selectively extracts the relevant cue information for the accumulation stage. These results suggest that the decision signal is effector-independent and general internal variable similar to saliency (or priority) signals and is constructed from signals filtered in the cue selector stage. As the existence of such a general choice evidence accumulation process has implications for models of decision making as well as other cognitive processes and I will briefly discuss the theoretical relevance of my findings.
Host: Nils Kolling