Congenitally blind humans use different stimulus selection strategies in hearing: An ERP study of spatial and temporal attention

Purpose: Superior temporal processing skills, both in the auditory and tactile system have been reported in blind as compared to sighted humans. The present experiment tested whether blind people prefer, as a possible consequence, temporal rather than spatial stimulus selection strategies. Methods: Eight congenitally blind adults were tested in a selective attention experiment that simultaneously manipulated spatial and temporal attention. Participants had to attend to an auditory offset stimulus demarcating the end of a short (600 ms) or long (1200 ms) interval. They had to detect slightly less intense offset markers at the attended point in time presented in the left (half of the trials) or right (other half of the trials) hemifield. Event-related potentials (ERPs) were recorded throughout the experiment. Results: Whereas the N1 was significantly enhanced by both spatial and temporal attention in the sighted (see Lange, Kramer, & Röder, 2006), only a temporal attention effect was found in the blind. Moreover, in both groups a second, longer lasting negativity was observed for offset markers presented at the attended as compared to the unattended spatial location. This negativity was modulated by temporal attention only in the blind. Conclusion: These results are consistent with the assumption of a higher priority of time for stimulus selection in the absence of vision from birth.