Effects of degradation of visual stimuli on components of the event-related potential (ERP) in go/nogo reaction tasks.

Investigated the effects of perceptual difficulty on ERP components in visual go/no-go discrimination tasks in 2 experiments with 19 dextral males (aged 17-28 yrs). ERPs were measured to randomly presented letters, requiring either a right-hand button-press response (go), or requiring no response (no-go). No-go stimuli elicited larger negative components at the frontal electrode sites and larger late-positive components at the central electrode sites than go stimuli. Intact stimuli elicited larger late-positive components and smaller slow wave components than degraded stimuli. Results are discussed in relation to cognitive and motor aspects of go and no-go stimuli and the possibility of contamination of ERP components with movement-related potentials.