Noise, biased probability and serial reaction.

Recent studies have shown that moderate intensity noise does influence performance although most studies showing effects of this level of noise have used verbal materials. An experiment showed that moderate intensity noise (85 dBC) also influences attentional selectivity in a serial reaction task which involved the processing of sensory information. Noise decreased response times to signals with high probabilities of occurrence but increased latencies for signals which occurred less frequently. Although attentional selectivity in noise depended on signal probability, it was not influenced by the spatial location of the signal. When a mode of responding is adopted in noise, subjects are often rather inflexible and continue to use this strategy even though it is inappropriate. This was demonstrated in the present study because the noise-induced bias continued even when the signal probabilities were returned to normal. Previous studies using higher noise intensities have shown that noise often increases the number of errors or gaps. The moderate intensity noise used in the present study did not have this effect.