When an observer detects a target in a rapid stream of visual stimuli, there is a brief period of time during which the detection of subsequent targets is impaired. In this study, event-related potentials (ERPs) were recorded from normal adult observers to determine whether this "attentional blink " reflects a suppression of perceptual processes or an impairment in postperceptual processes. No suppression was observed during the attentional blink interval for ERP components corresponding to sensory processing (the P1 and N1 components) or semantic analysis (the N400 component). However, complete suppression was observed for an ERP component that has been hypothesized to reflect the updating of working memory (the P3 component). Results indicate that the attentional blink reflects an impairment in a postperceptual stage of processing. Over the past several decades, the vast majority of studies of visual attention have examined the operation of attention across space. In the visual search task, for example, a target item must be detected within an array of distractor items that are presented at different locations from the target. In recent

Efficient categorizations of complex visual stimuli require effective encodings of their distinctive properties. However, the question remains of how processes of object and scene categorization use the information associated with different perceptual spatial scales. The psychophysics of scale perception suggests that recognition uses coarse blobs before fine scale edges, because the former is perceptually available before the latter. Although possible, this perceptually determined scenario neglects the nature of the task the recognition system must solve. If different spatial scales transmit different information about the input, an identical scene might be flexibly encoded and perceived at the scale that optimizes information for the considered task—i.e., the diagnostic scale. This paper tests the hypothesis that scale diagnosticity can determine scale selection for recognition. Experiment 1 tested whether coarse and fine spatial scales were both available at the onset of scene categorization. The second experiment tested that the selection of one scale could change depending on the diagnostic information present at this scale. The third and fourth experiments investigated whether scalespecific cues were independently processed, or whether they perceptually cooperated in the recognition of the input scene. Results suggest that a mandatory low-level registration of multiple spatial scales promotes flexible scene encodings, perceptions, and categorizations.

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unseen stimuli

The cognitive processes at work in masked priming experiments are usually considered automatic and independent of attention. We provide evidence against this view. Three behavioral experiments demonstrate that the occurrence of unconscious priming in a numbercomparison task is determined by the allocation of temporal attention to the time window during which the prime-target pair is presented. Both response-congruity priming and physical repetition priming vanish when temporal attention is focused away from this time window. These findings are inconsistent with the concept of a purely automatic spreading of activation during masked priming.

In 4 experiments, subjects classified visually presented target words as pleasant-unpleasant words or male-female first names. Prime words were similar (congruent) or dissimilar (incongruent) in meaning to targets. Brief duration of prime words (17, 33, or 50 ms), along with pre- and postmasking, prevented most subjects from perceiving their physical and semantic properties. By constraining response latencies to fall within a response window-a narrow time band that occurred earlier than subjects would ordinarily respond-these experiments consistently produced subliminal priming effects, indicated by greater error rates for incongruent than congruent priming trials. This conclusion was confirmed by analyzing magnitude of priming as a regression function of prime perceptibility using the method of A. G. Greenwald, M. R. Klinger, and E. S. Schuh (1995). The data of each experiment passed their significant-intercept criterion for demonstrating unconscious cognition. In the past decade, cognitive psychologists have been increasingly willing to discuss theories of unconscious cognition. This receptiveness is associated with a series of methodological advances that have led to an increasing variety of demonstrations of unconscious cognition (e.g.,

. In unconscious semantic priming, an unidentifiable visually masked word (the prime) facilitates semantic classification of a following visible related word (the target). Three experiments here provide evidence that masked primes are analyzed mainly at the level of word parts, not wholeword meaning. In Experiment 1, masked nonword primes composed of subword fragments of earlierviewed targets functioned as effective evaluative primes. (For example, after repeated classification of the targets angel and warm, the nonword anrm acted as an evaluatively positive masked prime.) Experiment 2 showed that this part-word processing was potent enough to oppose analysis at the whole word level. Thus, smile functioned as an evaluatively negative (!) masked prime after repeated classification of smut and bile. Experiment 3 found no priming when masked word primes contained no parts of earlier targets. These results suggest that robust unconscious priming (a) is driven by analysis of part-word infor...

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 as larger than 55, the novel masked prime 37 paradoxically facilitated the “larger ” response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory. This research started by asking how much semantic analysis occurs unconsciously in response to visually masked numbers. Experiment 1 set out specifically to resolve a discrepancy between two recently reported findings. When it became apparent that Experiment 1’s methods could address additional interesting questions about subliminal priming, those additional questions became

Introduction: the challenge of a science of consciousness Understanding consciousness has become the ultimate intellectual challenge of this new millennium. Even if philosophers now accept the notion that it is a "real , natural, biological phenomenon literally located in the brain" (Revonsuo, 2001), a view in harmony with the neuroscientist conception that "consciousness is entirely caused by neurobiological processes and realized in brain structures" (Changeux, 1983; Crick, 1994; Edelman, 1989), the real issue becomes: how to elaborate a science of consciousness? This challenging problem raises two questions. A first one is how to empirically define experimental paradigms in order to delineate a relevant and ultimately causal relationship between subjective phenomena and objective measurements of neural activity. Cognitive psychologists have now defined a variety of minimal experimental protocols which allow a fair comparison between conscious and non-conscious processing of informa

priming by combining a response window procedure, which increases priming effects by requiring rapid responding, and a regression analysis in which the regression intercept is a marker for unconscious cognition. The commentaries by B. A. Dosher (1998) and by P. M. Merikle and E. M. Reingold (1998) raise two questions about conclusions based on these methods: (a) Did Draine and Greenwald (1998) demonstrate an indirect effect (subliminal priming) in the absence of a direct effect (i.e., visibility of the subliminal priming words)? and (b) Did Draine and Greenwald (1998) demonstrate dissociation of conscious from uncon-scious cognition? The lint question has reassuring responses that are reviewed here. The second question is answered by pointing out that although Draine and Greenwald (1998) did not claim to have established such dissociation, they provided data that advance the plausibility of that conclusion. As recently as the mid-1980s, the word unconscious was taboo in many cognitive psychology journals. This taboo status began to unravel when a pair of articles by Marcel (1983 % 1983b) dared to use "unconscious " in their titles.