Unconscious processing of visual saliency

Ryota Kanai, Vincent Walsh

Institute of Cognitive Neuroscience and Department of Psychology

University College London

Motivation:Attention related areas show similar responses to attentional tasks.We would like to know how FEF and IPS play functionally distinct roles.

The goal: disentangle functions of attention areas (FEF and IPS)

Hypothesis:IPS is involved in bottom-up saliency computation, and FEF is involved in forming task set (template).

Difficulty (part of the hypothesis):Task set is also triggered by bottom-up events. So FEF appears to be stimulus driven (e.g. responses to saliency). So usually FEF and IPS behave in a similar way.

How do we tackle the problem?

Left Eye Right Eye

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We look at cortical responses to two types of attention capturing stimuli outside awareness.

1. Present an array of stimuli with a pop-out target to the suppressed eye.

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The goal is to see lateralized responses to the pop-out target in FEF and IPS

Proposed fMRI study

Conditions to compare:

Target in left visual field Target in right visual field

Target absent Event-related design

Each stimulus 3 sec

e.g.)

Inter trial interval: 3~8 sec

LV abs RV LV 6min scan (45 trials)x

4 visible + 4 invisible runs