The neural correlates of categorizing rotated objects

Miles, Katie

Psychology
September 2017

Thesis or dissertation


Rights
© 2017 Katie Miles. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
Abstract

The effects of categorizing rotated objects on the neural correlates of the N400 was investigated using a word-picture match task. The level of categorization was manipulated by presenting a basic or subordinate word prior to an image displayed at one of four orientations (0°, 60°, 120°, 180°). Participants’ task was to identify if the word and the image matched. The N400 component, which shows effects of semantic incongruity, was measured from the time phase 250 to 580 ms. Behavioural results found that reaction times were quicker for matched conditions over mismatched conditions. Basic mismatch conditions also showed faster reaction times versus subordinate mismatch as expected, however basic level categorization matched showed slower reaction times than subordinate level which was not expected. As predicted, reaction times for orientation showed a significant quadratic trend with 0° displaying the quickest reaction time. This increased for 60° and 120°, whereas reaction time then decreased for 180°. EEG results showed basic categorization had a lower amplitude on the N400 versus subordinate categorizations, as did mismatch conditions due to the higher level of semantic incongruity which has been identified in previous studies. The effect of orientation on the N400 differed depending on the level of categorization with only subordinate showing significantly more negative amplitudes. Possible reasoning of this is due to basic categorization not requiring transformation. The N400 correlates with semantic processing as when basic categorization mismatches was involved, less semantic information and higher incongruity correlated with more negative amplitudes of the N400.

Publisher
Department of Psychology, The University of Hull
Supervisor
Large, Mary-Ellen; Collins, Charles
Qualification level
Masters
Qualification name
MRes
Language
English
Extent
2 MB
Identifier
hull:16554
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