Variables of the Test of Variables of Attention (TOVA)
The Test of Variables of Attention (TOVA) measures four key variables: omission errors, commission errors, response time, and response time variability, which collectively assess attention, impulsivity, and processing speed in individuals with attention disorders.
Core Variables of the TOVA
Omission Errors: Measures inattention by tracking when a person fails to respond to target stimuli; higher scores indicate greater inattention problems 1
Commission Errors: Assesses impulsivity by measuring inappropriate responses to non-target stimuli; higher scores suggest greater impulsivity 1, 2
Response Time: Evaluates processing speed by measuring how quickly a person responds to target stimuli; slower response times may indicate attention processing deficits 3, 2
Response Time Variability: Measures consistency in response timing; greater variability suggests fluctuating attention and is often considered the most sensitive measure for attention disorders 1, 4
Derived Scores
D' (D-prime) Score: A sensitivity index that measures the individual's ability to discriminate between targets and non-targets, combining aspects of both attention and impulsivity 1
ADHD Score: A composite score calculated from the other variables that indicates the likelihood of attention deficit; used as a screening tool for ADHD 1, 4
Clinical Applications and Interpretation
The TOVA is designed to avoid confounding factors from language processing skills or short-term memory problems, making it useful for diagnosing ADHD across different populations 1
Performance on the TOVA shows moderate convergent validity with behavioral rating scales like the Child Behavior Checklist, particularly for hyperactivity and inattention symptoms 1
Response time variability, D' score, and ADHD score typically show the most significant differences between ADHD and non-ADHD groups 1, 4
The test can be administered to both children and adults, with research showing it maintains validity across different age groups 3, 2
Important Considerations
Time of day may affect certain TOVA variables, with afternoon testing potentially resulting in faster response times but more commission errors (increased impulsivity) compared to morning testing 3, 2
Caffeine consumption can significantly improve response times, particularly in individuals who typically consume little caffeine, which should be considered when interpreting results 2
The TOVA demonstrates good internal consistency (mean of 0.81 across variables) but individual test scores show less reproducibility over time compared to group scores 5
Response time and response time variability show greater temporal stability and test-retest reliability than omission and commission errors 5
The Stroop test, which also evaluates executive functions including psychomotor speed and cognitive flexibility, is often used alongside the TOVA for comprehensive assessment of attention and executive function 6