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The neural profile of eye-movements supporting memory retrieval in the absence of visual input

IMC-Lecture by Richard Dewhurst, PhD Lund University

Info about event

Time

Tuesday 8 December 2015,  at 11:00 - 13:00

Location

IMC Meeting Room

Organizer

IMC

The IMC hosts Richard Dewhurst, experienced researcher with a focus on eye-tracking techniques (Co-author of "Eye-tracking: A comprehensive guide to methods and measures", with Kenneth Holmqvist), giving a talk about his current work about eye-movements and memory retrieval in the absence of visual input.  

Abstract:

 When remembering an image rich in spatial detail we move our eyes in a spatio-temporal pattern which closely reflects the layout of the scene (Johansson, Holsanova, Dewhurst, & Holmqvist, 2012). This is the case even when there is nothing to look at—the so-called “looking at nothing” effect on memory retrieval (e.g. Richardson, Altmann, Spivey, Hoover, 2009, Johansson & Johansson, 2014). As well as raising tantalising questions about how to compare these “scanpaths”, the fundamental issue concerns the mnemonic role such eye-movements play, and how this is sub-served in the brain. I will describe a combined Event-Related Potential and eye tracking study which aims to uncover the neural components underpinning the memory benefit of fixating empty regions of space, which were previously occupied by the item to be recalled. Participants performed a visual encoding task designed to establish a deep episodic memory trace. They inspected an array of 24 objects and were asked to remember as much as possible about their spatial arrangement. In a subsequent retrieval phase participants were auditorily probed regarding the locations of the memorised objects. Critically, they fixated within a now blank region of the display, either congruent to the objects' original location, or spatially dislocated and incongruent. The results demonstrate that the facilitatory behavioural effects of eye movement congruency, can be mapped onto the modulation of posterior ERP slow waves, previously suggested to be associated with re-construction and monitoring of episodic memory representations (e.g. Johansson & Mecklinger, 2003). The results suggest that episodic memory retrieval is an aspect of cognition embodied by eye-movements, not merely in an epiphenomenal sense. Looking at the right location gives rise to a greater overlap between encoding-, and retrieval-related neural activity, consequently boosting memory performance in line with the encoding-retrieval match principle (cf. Rugg, Park, & Uncapher, 2008). This is a novel demonstration of the neural profile of memory enhancement driven solely by fixation location, in the absence of visual input.