Color Vision and its mechanisms in College students with Attention Deficit Hyperactivity Disorder

Attention Deficit Hyperactivity Disorder (ADHD) is the most prevalent childhood psychiatric disorder that was first described medically in 1775. However, it is still unclear what the `deficit' is in this clinical condition. Current evidence suggests that its etiology is heterogeneous encompassing various factors that interact and influence each other. Most current theories posit that alterations in the prefrontal cortex and impairments in the associated executive functions and other higher-order processing underlie ADHD symptoms. However, accumulating evidence attests to anomalies in vision in ADHD that cannot be explained by existing models of ADHD. In particular, children with ADHD have been found to exhibit color perception problems (particularly blue), which may be best explained by the `retinal dopaminergic hypothesis.' The hypothesis proposes that low dopamine in the central nervous system induces a hypo-dopaminergic state in the retina, which in turn would have deleterious effects on short wave-length cones (`blue-cones'). Some support exists for this hypothesis but findings are inconsistent and have focused on only one feature of color: namely that of hue in the children with ADHD. Accordingly, for this dissertation, I sought to extend the investigation on color vision by testing two key characteristics of color (hue and saturation) in college students with ADHD using both clinical (Mollon-Reffin Minimalist Color Vision Test, Farnsworth-Munsell 100 Hue Test), and psychophysical methodologies. Specifically, I first tested hue discrimination ability in a college student population with ADHD. Upon replicating evidence of problem in blue hue discrimination in college students with ADHD, I expanded the scope of previous findings on hue discrimination ability by also examining color saturation discrimination ability. Using a psychophysical paradigm, I revealed a problem in color saturation discrimination of red and blue color in another sample of college students with ADHD - a finding which is partially consistent with the retinal dopaminergic hypothesis. Lastly, I explored role of exogenous covert attention in color saturation discrimination in that same group of college students with and without ADHD to ascertain whether attention problems might in part explain the color perception problems in ADHD. The latter study indicated that covert attention does not differentially influence color saturation/contrast sensitivity perception in college students with ADHD than healthy peers. The possibility of color perception problems in ADHD is important, given the extensive use of color in educational settings, as well as the frequent use of color stimuli in many of the standard neuropsychological tests used in the assessment for ADHD and related disorders. Most importantly, the present findings of altered color perception in ADHD highlight the need for further research on other perceptual capacities in ADHD.

Department dc:contributor.department

Applied Psychology and Human Development

Year dc:date.issued

2015

Author dc:creator

• Kim, Soyeon

Advisor dc:contributor.advisor

• Tannock, Rosemary

• ADHD
• College students
• Color vision
• Exogenous Covert attention

Handle dc:identifier.uri

http://hdl.handle.net/1807/94496

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/94496