The present study examined the effects of spatial preening on identification of a single object appearing in an otherwise empty visual field. A digit target was preceded by a valid, neutral, or invalid location cue, presented either peripherally or centrally. The target was followed by either a single mask or multiple masks covering the target and nontarget (empty) locations. Precuing significantly affected identification accuracy when multiple masks were used but had little effect when the target was followed by a single mask. The results strongly favor a model in which spatial precuing allows the contents of noncued locations to be excluded from decision (and possibly perception). Exclusion may or may hot facilitate performance, depending on what is there to be excluded.

The ability of human observers to discriminate the orientation of a pair of straight lines differing by 3°improved with practice. The improvement did not transfer across hemifield or across quadrants within the same hemifield. The practice effect occurred whether or not observers were given feedback. However, orientation discrimination did not improve when observers attended to brightness rather than orientation of the lines. This suggests that cognitive set affects tuning in retinally local orientation channels (perhaps by guiding some form of unsupervised learning mechanism) and that retinotopic feature extraction may not be wholly preattentive.

Pillsbury (1908) suggested that deciding to search for something in a scene consists of nothing more than forming a visual image of the target. If so, imaging should trigger search even when it would be more advantageous not to search. Subjects were cued to form an image of a specified object (e.g., tiger) and to press a key when they had done so. This initiated the presentation of a sequence of pictures, with a single target digit interspersed; the subject's task was to report this digit. The sequence contained a picture of the same type of object that the subject had just imaged (e.g., a tiger), either before or after the target digit. If this picture was detected involuntarily, an attentional blink should have impaired digit detection when the picture preceded the digit. This was confirmed in two experiments, even when instructions specifically encouraged subjects to discard the image and to avoid searching for it. The results support Pillsbury's hypothesis.

This study examined whether or not vernier acuity would be improved if the location of a briefly presented vernier stimulus was pre-cued. The vernier target appeared alone, or together with straight lines or ellipses. Effects of spatial pre-cuing were found only when straight line distractors were present. It is suggested that since the straight lines are confusable with the vernier targets, they introduce statistical noise in decision. Precuing the most probable location that contains a target may help by allowing this noise to be excluded.

The subjects in this study made incongruent naming responses to words and pictures that were presented on alternate trials'(e.g, say "car" to BIKE). Their response time was longer ifthe correct response for the current trial was the name of the stimulus presented on the preceding trial, as compared with a control condition. These results suggest that the tendency to produce the (congruent) name of the stimulus is automatically activated and then inhibited. The "negativepriming" effects appeared stronger for words where pictures were primes than for pictures where words were primes. The implications of these results for negative priming and stimulus-response compatibility are discussed,