The TOVA test checks for the presence of ADHD by testing the ability of the child to sustain performance of a long task. This test is computerized and is based on the analysis of responses to stimuli - omissions, additions, errors, etc... The child observes what's represented on the computer screen for a set period of time, and he is supposed to respond to one type of stimulus and to ignore the other type. The test measures the speed and accuracy of the processing of information that the child performs by means of comparing the results to norms characterizing children of his age.
The main measures this test checks are:
1. Attention/Lack of Attention - correct responses and incorrect responses to the intended stimulus
2. Impulsivity - incorrect responses to unintended stimuli
3. Response time - the amount of time need for the brain to react to the stimulus. The speed is very important since children who suffer from ADHD are much slower. Similarly, the speed responds well to medication.
4. Change in response time - does the brain react consistently or inconsistently to stimuli. This is the most sensitive measure since children suffering from ADHD show before anything else a lack of consistency in responses to stimuli.
The second part of the TOVA is evaluating the effectiveness of drug treatment. The most accepted drug treatment is with Ritalin, both because of its effectiveness and also because of its short response time. Performance of the test without treatment, then afterwards under the influence of Ritalin, allows receiving an objective estimation of the effectiveness of drug treatment.