Recognition potential latency and word image degradation.

Ten subjects viewed a stream of meaningless background images in which English words occasionally appeared. A subject indicated detection of a word by lifting the index finger of the preferred hand. He received payment based on his performance. A computer program degraded half of the word images, removing a fraction of the lit pixels and replacing them with others that resembled the background images. The recognition potential (RP) was recorded from occipital electrodes. Degrading the word images increased the peak latency of the RP from 231 to 266 msec. The 35 msec difference was comparable to the 36 msec reaction time (RT) difference. At 395 and 431 msec, RT occurred about 165 msec after the RP peak. The results indicated the RP is closely related to a recognition process. The study did not resolve whether it is concurrent with that process or immediately follows it. The RP's sensitivity to image degradation and its short latency make it unlikely that N2 and P3 are concurrent with the recognition process.