Knowledge that Transforms

Accumulated evidence from electrophysiology and neuroimaging suggests that face perception involves extrastriate visual mechanisms specialized in processing physiognomic features and building a perceptual representation that is categorically distinct and can be identified by face-recognition units. In the present experiment, we recorded event-related brain potentials in order to explore possible contextual influences on the activity of this perceptual mechanism. Subjects werefirst exposed to pairs of small shapes, which did not elicit any face-specific brain activity. The same stimuli, however, elicitedface-specific brain activity after subjects saw them embedded in schematic faces, which probably primed the subjects to interpret the shapes as schematic eyes. No face-specific activity was observed when objects rather than faces were used to form the context. We conclude that the activity of face-specific extrastriate perceptual mechanisms can be modulated by contextual constraints that determine the significance of the visual input.

Visual attention enables observers to extract and process high-priority information in the visualfield. Controversy remains as to whether or not observers can ignore information that falls within the spatial beam of attention. We used an objective physiological measure, the steady-state visual evoked potential (SSVEP), to investigate this question. A stream of flickering small, uppercase letters was embedded in the center of a stream of large, uppercase letters. A unitary beam would result in no difference of the SSVEP amplitude elicited by the small letter stream when it was attended versus ignored (i.e., when subjects attended the large letter stream). Contrary to this prediction, SSVEP amplitude increased by almost 100% when the small letter stream was attended compared with when it was ignored. The results support the notion that the attentional spotlight can be formed like a doughnut, processing central information differentially depending on whether it is attended or ignored.

Age-related deficits in memory are greater as encoding and retrieval tasks require more reflective (self-generated or executive) processing. One problem in developing more specific models of age-related changes in cognition is that the tasks studied tend to be complex and vary in the combinations of component cognitive processes they recruit. Here we report an age-related deficit in one of the most elementary, but critical, components of reflection: refreshing a just-activated representation. Impairment in such a process potentially has a wide-ranging impact on all higher-order cognition.

Current theories of dual visual systems suggest that color is processed in a ventral cortical stream that eventually gives rise to visual awareness but is only indirectly involved in visuomotor control mediated by the dorsal stream. If the dorsal stream is indeed less sensitive to color than the ventral stream, color stimuli blocked from awareness by visual masking should also be blocked from guiding fast motor responses. In this study, pointing movements to one of two isoluminant color targets were preceded by consistent or inconsistent color primes. Trajectories were strongly affected by priming, with kinematics implying a continuous flow of color information into executive brain areas while the finger was already moving. Motor effects were more sensitive to color of the primes than were deliberate attempts to identify the primes in forced-choice tasks based on visual awareness. Priming was observed even when masking was complete.

The present article provides evidence for the role of participants' familiarity with units of measurement in categorical accentuation with unidimensional physical estimates. Belgian and American participants estimated the lengths of lines varying in length. Depending on the condition, the lines were or were not systematically associated with categorical labels, and the estimates were made either in inches or in centimeters. Consistent with our predictions, (a) categorical accentuation was higher when the lines were systematically categorized than when they were not, and (b) this effect was stronger when participants reported their estimates in an unfamiliar measurement unit (i.e., Belgian participants using inches, and American participants using centimeters). These findings support the view that people's reliance on categorical information is more likely to emerge given uncertain contexts of judgment. Additionally, they may help explain why researchers have had difficulties replicating the categorical accentuation effect in the past.

For better or for worse, and opinions are divided on this score, the research program of Daniel Kahneman and the late Amos Tversky now represents psychology’s leading intellectual export to the wider academic world. Scholars with little else in common, from such far-flung fields as medical diagnosis, the law, public opinion, international relations, and microeconomics, share some working knowledge of the principles that Kahneman and Tversky have invoked to explain why people stray from classic benchmarks of rationality for judgment and choice: principles such as heuristics, framing, mental accounting, and the psychophysics of gain, loss, and probability-weighting functions

Although not previously addressed by researchers of spatial cognition or affect, the combination of spatial and affective information is essential for many approach and avoidance behaviors, and thus for survivaL We provide the first evidence that through incidental experience, people form representations that capture correlations between affective and spatial information. Participants were able to do so even when the correlation was weak, they were not told to look for the correlation, and the stimuli varied on multiple other dimensions besides valence. In addition, people were more sensitive to the presented correlation when stimuli were negative than when they were positive. This asymmetry in representation may stem from underlying differences in the activation functions for positive and negative hedonic information processing.

Depressed mothers use less of the exaggerated prosody that is typical of infant-directed (ID) speech than do nondepressed mothers. We investigated the consequences of this reduced perceptual salience in ID speech for infant learning. Infants of nondepressed mothers readily learned that their mothers' speech signaled a face, whereas infants of depressed mothers failed to learn that their mothers' speech signaled the face. Infants of depressed mothers did, however, show strong learning in response to speech produced by an unfamiliar nondepressed mother. These outcomes indicate that the reduced perceptual salience of depressed mothers' ID speech could lead to deficient learning in otherwise competent learners.

Williams syndrome (WS) is a rare genetic disorder that results in profound spatial cognitive deficits. We examined whether individuals with WS have intact perception of biological motion, which requires global spatial integration of local motion signals into a unitary percept of a human form. Children with WS, normal mental-age-matched children, and normal adults viewed point-light-walker (PLW) displays portraying a human figure walking to the left or right. Children with WS were as good as or better than control children in their ability to judge the walker's direction, even when it was masked with dynamic noise that mimicked the local motion of the PLW lights. These results show that mechanisms underlying the perception of at least some kinds of biological motion are unimpaired in children with WS. They provide the first evidence of selective sparing of a specialized spatial system in individuals with a known genetic impairment.

Many languages have no basic color term for "blue." Instead, they call short-wavelength stimuli "green" or "dark". We show that this cultural, linguistic phenomenon could result from accelerated aging of the eye because of high, chronic exposure to ultraviolet-B (UV-B) in sunlight (e.g., phototoxic lens brunescence). Reviewing 203 world languages, we found a significant relationship between UV dosage and color naming: In low-UV localities, languages generally have the word "blue"; in high-UV areas, languages without "blue" prevail. Furthermore, speakers of these non-"blue" languages often show blue-yellow color vision deficiency. We tested our phototoxicity hypothesis in a color-naming experiment, using computerized, colorimetric simulations of Munsell colors as viewed through clear and brunescent lenses. As predicted, our young subjects used "blue" as in English when the simulated lens was clear, but named colors as in tropical languages when the lens was dense. Our within-subjects design precludes a cultural explanation for this result.