RESULTS AND DISCUSSION

A significant difference in the peak latency of the P1 wave between the congenitally blind (59.85±8.7 msec.) and subjects with normal vision (66.48 + 6.7 msec.) was noted. These values are the average of 18 values per group, i.e., n=9, with two replications. For the two-factor analysis, for groups F1.32 =6.24 (F=5.53 at P<.05, two-tailed). The effect size for this ratio was .85. There was no significant difference between replications (ns) and the interaction was not significant (ns). The peak amplitude of the P1 wave was not statistically significantly different between groups congenitally blind (0.54± 0.4mV) and with normal vision (0.70±0.5 mV) or between replications.

The present results indicate that the P1 peak latency is significantly shorter for the congenitally blind compared to the subjects with normal vision. A shorter latency suggests enhanced efficiency of information processing in the underlying neural centers. The P1 wave is thought to correspond to either subcortical structures such as the brainstem ascending reticular activating system (Cacace, et al., 1990) or the dorso-posterolateral part of the Heschl's gyrus, i.e., the primary auditory area (Liegeois-Chauvel, et al., 1994). Hence the present results suggest that these neural centers along the auditory pathway may function more efficiently in the blind, in addition to those more distal reflected by NI, PI, P2 (Niemeyer & Starlinger, 1981) and those more proximal, i.e., Nb wave (Naveen, et al., 1997).