Abstract
Background:
Response inhibition has been proposed as a core element of attention-deficit / hyperactivity disorder (ADHD). ADHD has two subtypes: the hyperactivity and combined subtype (ADHDcom) was considered to have more inhibition deficit, while the inattentive subtype (ADHDin) was not (Barkley, 1997). The stochastic resonance model proposed that noise exerts a positive effect on cognitive performance for ADHD (Söderlund et al., 2007). The current study addressed the issue of the facilitation / interference effect of noise on patients with ADHD by adopting a cross-modality stop-signal task.
Method:
The cross-modality stop signal task contained a visual discrimination task and an auditory stop signal. Participants were asked to respond to the visual stimuli, and they were asked to withhold their response when the stop signal was presented (25% of trials). The stop signal was a pure tone embedded background noise with various sound levels (no noise, 35 dB, 55 dB). The stop signal reaction time (SSRT) was estimated following Logan et al. (1984) as an index for inhibition function.
Result:
The result revealed that the SSRTs for ADHDcom were significantly longer than those of ADHDin. The noise did not improve inhibition performance; rather, an interference effect was evident for both subtypes of ADHD. Our result failed to support the finding of Söderlund et al. (2007).