Endogenous attention and illusory line motion reexamined

P. Downing and A. Treisman's (1997) failure to replicate an effect of endogenous attention on the direction of illusory line motion (ILM) was reexamined. Four experiments with slightly modified stimulus presentation methods based on gradient theories of ILM found that endogenous attention directed to 1 of 2 similar priming objects is capable of influencing experienced motion direction within a subsequently presented line. The endogenous effect on ILM was consistent with a concomitant response-time discrimination task, was robust across naive and informed participants, occurred whether eye fixation was monitored or not, and occurred under conditions where multiple motion response categories were available to participants. The endogenous effect disappeared when participants moved their eyes to the attended item, when there was no motivation to endogenously attend, and when the presentation methods of P. Downing and A. Treisman (1997) were used.