The Effects of Visual Stimulation on the Mathematics Performance of Children with Attention Deficit Disorder/hyperactivity Disorder
Lee, David L., Zentall, Sydney S., Behavioral Disorders
Children with attention deficit hyperactivity disorder (ADHD) often demonstrate significant educational (Zentall, 1993) and behavioral deficits (Barkley, DuPaul, & McMurray, 1990). Estimates of the prevalence of ADHD suggest that 3% to 7% of school-aged children have the disorder, which is characterized by excessive levels of motor activity, impulsivity, inattention, and an inclination to seek immediate reinforcement (Barkley, 1998; Douglas, 1985). Psychoeducational research in ADHD has generally been conducted under one of two stimulation-based paradigms.
Two Models of ADHD Research
Early researchers had hypothesized that hyperactivity was a result of excess environmental stimulation (Cruickshank, Bentzen, Ratzenburg, & Tannhauser, 1961; Strauss & Lehtinen, 1947). This stimulus "overflow" or overarousal model proposed that excessive behavior (i.e., hyperactivity) occurred when stimulus input surpassed processing capacity. After this critical threshold had been surpassed, behavior increased as a linear function of stimulation. This model suggested that children with ADHD have a decreased level of processing capacity and are unable to dampen stimulation as well as their peers. Although it is still widely accepted by many applied professionals, subsequent research has failed to support overarousal as a tenable theory of ADHD (for review see Zentall & Zentall, 1983).
The Optimal Stimulation Model
Based on the optimal stimulation theory (e.g., Leuba, 1955), a second theory posits that hyperactivity results from decreased levels of effective environmental stimulation (Zentall, 1975). According to the optimal stimulation theory, organisms work to maintain optimal levels of stimulation through instrumental activity, much like the body works to maintain homeostasis by regulating levels of heat, food, and water. Zentall suggests that individuals with ADHD require more stimulation and novelty than so-called "normal" individuals to achieve and maintain an optimal level of arousal in a given context. The behavior of children with ADHD can be "normalized" (a) by allowing the child to self-generate stimulation (e.g., through activity, attention directed toward novelty); (b) through the use of stimulant medication, which reduces the need for the child to self-generate stimulation; or (c) by increasing the level of task or environmental stimulation (Zentall, 1993).
Studies assessing the effects of environmental stimulation on the behavior of individuals with ADHD have shown that color added to the environment or embedded within simple attentional tasks results in decreased activity levels and enhanced performance and persistence (Zentall, 1986; Zentall & Dwyer, 1989; Zentall, Falkenberg, & Smith, 1985; Zentall & Meyer, 1987; Zentall & Zentall, 1976). For example, Zentall (1986) examined the effects of within-task stimulation on an attentional task (i.e., adding color to slides on a visual continuous performance task) and found that the students with ADHD made more errors and were more active than comparisons in the low stimulation condition, whereas no differences between groups were found in the high stimulation condition. However, the location of stimulation within the task moderates the effects achieved. That is, color added to non relevant features of tasks competes with task-related stimulation (especially to new or complex tasks). This competing source of stimulation can result in decreased performance and increased inappropriate behavior (Zentall & Kruczek, 1988; Zentall, Zentall, & Booth, 1978).
The results of studies examining the effects of environmental stimulation have yet to be incorporated into the development of traditional behavioral support plans for children with ADHD across types of tasks and environments (e.g., school and home). Traditional support plans, often derived from the operant paradigm, consisted of arranging consequences to either increase or decrease occurrences of a targeted behavior. …