When 2 targets are presented among distractors in rapid serial visual presentation, correct identification of the 1st target results in a deficit for a 2nd target appearing within 200-500 ms. This attentional blink (AB; J. E. Raymond, K. L. Shapiro, & K. M. Arnell, 1992) was examined for categorically defined targets (letters among nonletters) in 7 experiments. AB was obtained for the 2nd letter target among digit distractors (Experiment 1) and also for a 3rd target (Experiment 2). Results of Experiments 3-5 confirmed that AB is triggered by local interference from immediate posttarget stimulation (Raymond et al., 1992) and showed that AB is modulated by the discriminability between the 1st target and the immediately following distractor. Experiments 5-7 further examined the effects of both local interference and global discriminability. A 2-stage model is proposed to account for the AB results.

Three converging procedures were used to determine whether pictures presented in a rapid sequence at rates comparable to eye fixations are understood and then quickly forgotten. In two experiments, sequences of 16 color photographs were presented at rates of 113, 167, 250, or 333 msec per picture. In one group, subjects were given an immediate test of recognition memory for the pictures and in other groups they searched for a target picture. Even when the target had only been specified by a title (e..g., a boat) detection of a target was strikingly superior to recognition memory. Detection was slightly but significantly better for pictured than named targets. In a third experiment pictures were presented for 50, 70, 90, or 120 msec preceded and followed by a visual mask; at 120 msec recognition memory was as accurate as detection had been. The results, taken together with those in 1969 of Potter and Levy for slower rates of sequential presentation, suggest that on the average a scene is understood and so becomes immune to ordinary visual masking within about 100 msec but requires about 300 msec of further processing before the memory representation is resistant to conceptual masking from a following picture. Possible functions of a short-term conceptual memory, such as the control of eye fixations, are discussed. This research was supported by grants from procedure in which the subject responds at the National Institute of Mental Health to the the tjme of view i ng In an earlier experiauthor (MH-13988-01) and by Grant and Spencer \cp n n er 107^ cnhiprt, o Pa rrrw>r1 fnr Foundation grants to H. L. Teuber. The assistance ment [(hotter, iy/5) subjects searched lor of Miriam I. Williams, Toby Caplin, and Barbara a target picture m a sequence and responded Faulconer is gratefully acknowledged. as soon as they saw it. Some subjects were Requests for reprints should be sent to Mary C. shown the target picture itself in advance MaShuferiSteof -JS^'c^ZSZ, ^d others ™* «*« °^ a brief title for Massachusetts 02139.the picture (e.g., a baby reaching for a

Does knowledge about which objects and settings tend to co-occur affect how people interpret an image? The effects of consistency on perception were investigated using manipulated photographs containing a foreground object that was either semantically consistent or inconsistent with its setting. In four experiments, participants reported the foreground object, the setting, or both after seeing each picture for 80 ms followed by a mask. In Experiment 1, objects were identified more accurately in a consistent than an inconsistent setting. In Experiment 2, backgrounds were identified more accurately when they contained a consistent rather than an inconsistent foreground object. In Experiment 3, objects were presented without backgrounds and backgrounds without objects; comparison with the other experiments indicated that objects were identified better in isolation than when presented with a background, but there was no difference in accuracy for backgrounds whether they appeared with a foreground object or not. Finally, in Experiment 4, consistency effects remained when both objects and backgrounds were reported. Semantic consistency information is available when a scene is glimpsed briefly and affects both object and background perception. Objects and their settings are processed interactively and not in isolation.

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