The central executive and object recognition

Abstract

The present study focused on the involvement of the central executive in non-optimal
views recognition. Although research has implied that there may be a role for
resources outside of the classic ventral visual stream in such recognition, none have
directly investigated a frontal lobe contribution, using dual task methodology. A dual
task procedure, based on the working memory model of Baddeley and Hitch (1974),
was developed to answer this (and related) questions.
The first series of experiments tested the view dependency of stimuli rotated
in the depth plane, taken from the Birmingham Object Recognition Battery (Riddoch
& Humphreys, 1993), piloting them in a reaction time paradigm. Four experiments
demonstrated decremental performance in terms of response times and error rates for
non-optimal, compared to optimal, view recognition.
Having established a role for executive processes in the recognition of stimuli
rotated in depth, two further experiments investigated the effect of a central executive
secondary task on the recognition of alternative forms of non-optimal views. Results
mirrored those in the first set of studies, but expanded on these in suggesting that
although the central executive appears to be involved in the recognition of depth
rotated stimuli, this does not appear to be the case for stimuli rotated in the picture
plane, or for stimuli with a critical feature occluded. Two subsequent experiments
addressed the question of category level effects on non-optimal view recognition.
Data suggested that subordinate catego1isation required additional resources,
compared to basic level categorisation, and added further support for an executive
contribution in the recognition of depth rotated, but not minimal features stimuli.
The final group of four experiments involved the development of a novel
paradigm to investigate two specific subcomponents of executive function: search and
inhibition. Results suggested that both search and inhibition appear to contribute to
recognition of depth rotated stimuli, but that their involvement was heavily modulated
by the frequency of each subcomponent. Findings are discussed in relation to object
recognition theories, and the neural substrates mediating object constancy.

Date of Award	Sept 2003
Original language	English
Awarding Institution	University of Wales, Bangor
Sponsors	Economic and Social Research Council (ESRC)
Supervisor	Oliver Turnbull (Supervisor) & Charles Leek (Supervisor)