Abstract
Previous research has shown that attention can be oriented exogenously without awareness of the stimuli responsible (McCormick, 1997). The present study asks whether the identity of implicitly presented cues can guide attention. The task consists of a two-location search using simultaneous presentation of a target on one side of a central fixation cross and a distractor on the other side. 350 milliseconds prior to the appearance of the target and distractor a cue appeared at one of the peripheral target locations (the number 2 or 9). The cue was visually crowded by one ‘X’ on each side making the digit's identity impossible to report (0 of 11 subjects reported that the character between the X's was a digit). Two types of cues were used and both were 100 percent valid. On one third of the trials a predictive digit cue always appeared on the same side as the target. On one third of the trials a different digit, the anti-predictive cue, always appeared opposite the target. On the side opposite the cue ‘XXX’ appeared, and on the control conditions ‘XXX’ appeared at both locations. With sufficient experience (approx. 300 trials), subjects implicitly learned the association between the cues and target locations and both types of cues led to improved reaction time (10-15 ms) compared to the baseline no-cue condition. Guidance of attention by implicit endogenous information will be discussed.
Supported in part by NIH EY014193