PSYCHOLOGICAL SCIENCE Research Article VISUAL PRIOR ENTRY

— It has long been claimed that attended stimuli are perceived prior to unattended stimuli—the doctrine of prior entry. Most, if not all, studies on which such claims have been based, however, are open to a nonattentional interpretation involving response bias, leading some researchers to assert that prior entry may not exist. Given this controversy, we introduce a novel methodology to minimize the effect of response bias by manipulating attention and response demands in orthogonal dimensions. Attention was oriented to the left or right (i.e., spatially), but instead of reporting on the basis of location, observers reported the order (first or second) of vertical versus horizontal line segments. Although second-order response biases were demonstrated, effects of attention in accordance with the law of prior entry were clearly obtained following both exogenous and endogenous attentional cuing. The doctrine of prior entry—that attended stimuli are perceived earlier than unattended stimuli—has a long history in experimental psychology, stretching back to the very origins of the study of perception Some of the most compelling evidence demonstrating that attention influences the perception of arrival times comes from recent studies using temporal-order judgment (TOJ) tasks (e. In a typical study, attention is oriented to the left or right of fixa-tion, and observers are required to indicate which of two subsequent stimuli, one presented on the left and one on the right, was presented first. In most studies, the interval between the two stimuli is varied, and the point of subjective simultaneity (PSS) is determined for each type of cue. The PSS represents the interval for which the observer perceives the stimuli as simultaneous and is computed as the interval at which " left first " and " right first " responses are reported equally often ; that is, the PSS is the point at which observers are maximally uncertain as to the correct response. The accelerative effect of attention that is presumed by prior entry is indicated by a shift in the PSS. We believe genuine prior entry should be defined as a perceptual effect on arrival times attributable to attentional modulation (cf. Titchener, 1908) once the opportunities and incentives for response-and decision-level contributions to the measured PSS have been minimized. One such postperceptual mechanism that has recently been highlighted A simple response-bias account of the shift in PSS postulates that observers may simply report the side to which they had been instructed to attend (Frey, …