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An analysis of embedded figures test per An analysis of embedded figures test per... - Complex Object ()
An analysis of embedded figures test performance in individuals with austistic-like traits / Renita A. Almeida
[Truncated abstract] The Embedded Figures Test (EFT; Witkin, Oltman, Raskin, & Karp, 1971) is a search task that involves detecting a simple closed-contour shape hidden within a complex structure. Individuals with an autism spectrum disorder (ASD) are faster detecting embedded figures relative to typically developing controls (de Jonge, Kemner, & van Engeland, 2006; Jarrold, Gilchrist, & Bender, 2005; Jolliffe & Baron-Cohen, 1997; Pellicano, Gibson, Maybery, Durkin, & Badcock, 2005). Superior EFT performance is not only observed in ASD groups relative to controls; those in the typically developing population with high levels of autistic-like traits also demonstrate enhanced performance relative to those with low levels of such traits (Grinter, Maybery et al., 2009; Grinter, Van Beek, Maybery, & Badcock, 2009; Russell-Smith, Maybery, & Bayliss, 2010). Examining individuals in these latter groups can be a useful method to extend current knowledge of complex ASDs by avoiding confounds such as co-morbidity associated with ASD samples. While enhanced EFT performance linked to autism has been repeatedly observed, it is not clear what underlying mechanism(s) allow(s) for such superiority. The aim of this thesis was to examine which specific aspects of the stimuli employed in the EFT are critical to enable superior visual search performance by those with high levels of autistic-like traits. Four series of experiments compared performance of groups of individuals with either high or low levels of autistic-like characteristics, as determined by the Autism-Spectrum Quotient (AQ; Baron-Cohen, Wheelwright, Skinner, Martin, & Clubley, 2001), on the EFT and on a number of novel visual tasks designed to systematically investigate potential critical components of the EFT.
The first series, reported in Chapter Two, introduced a basic search task which contained radial frequency (RF) patterns as stimuli. RF patterns are deformed circular closed-contours created by sinusoidally modulating the radius of a circle, where the number of cycles of modulation defines the RF number. The EFT simple target shapes are closed-contours, and because considerable recent work on discrimination of closed-contours has utilised RF patterns, employing these well-defined shapes may aid clarification of the underlying processes. The task was to detect a target RF3 (triangular-shaped) pattern from an array of spatially discrete distracter RF4 (square-like) patterns. The number of distracter RF patterns was varied to provide a measure of visual search performance, specified as the change in reaction time (RT) with increasing set size (SS), commonly referred to as the gradient or slope of the linear function. Overlap of elements, one component of the EFT, was introduced to determine whether it was critical to the high AQ search advantage. Increasing overlap of elements reduced search efficiency of both groups in a systematic way, but the relative difference between the two groups gradients remained the same. The high AQ group were faster overall and had a shallower gradient in all RF search conditions. They also had significantly shorter EFT RTs and fewer errors relative to the low AQ group. Performance on the RF search tasks and EFT was correlated, providing some support for the convergent validity of the RF search task...
Thesis (Ph.D)--University of Western Australia, 2011
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