Stimulus categorization by brain-damaged patients

Patients with localized insult to the right hemisphere, or to either the anterior or the posterior portion of the left hemisphere, as well as neurologically intact controls, evaluated stimuli on a seven-point rating scale for their degree of category membership. The stimuli were taken from one of two continua, one composed of fruit and vegetable items, and the other of items differing in hue and shape. Different subsets of stimuli provided different contexts for the judgments of category membership. The two left-hemisphere groups showed anomalies in categorizing the fruit and vegetable items but not the perceptual items, while the reverse was true for the right-hemisphere patients. Moreover, both left-hemisphere groups demonstrated context effects in their judgments of the representativeness of the fruit and vegetable items, but differed in the way in which they responded to changing contexts. Left posterior patients demonstrated weak category boundaries and even reclassified items. In contrast, patients with left anterior damage showed highly categorical responses and less differentiation of items within a category. All groups showed striking context effects in judgments of perceptual items in terms of changes in representativeness ratings and the location of a category boundary. Alternative interpretations of the results are offered.     

Automaticity and the capture of attention by a peripheral display change

The proposal that peripheral visual changes (cues) tend to summon attention automatically was tested by studying the effect of peripheral cueing on simple detection latency. Delay between cue onset and target onset, the contingent relationship between cue location and target location, and instructions to subjects were manipulated. Results showed that a peripheral display change could capture attention even when the target was far more likely to appear at an uncued location. When subjects were explicitly informed that targets were likely to appear away from the cued location they were able to suppress this effect, but were unable completely to reverse it by rapidly orienting attention towards the uncued side. Hence the process appears to be automatic in the sense that it occurs unless there are explicit instructions to the contrary. With explicit instructions the processing operation can be suppressed, but not completely reversed. This work was supported by the U.K. Admiralty Research Establishment (Research Agreement No. 53482).     

Acomparison of the musical scales of the ancient Chinese bronze bell ensemble and the modern bamboo flute

We compare over a two-octave range the tonal, interval, and scale relationships of an ancient Chinese bell ensemble of the Zhou Dynasty and a modern bamboo flute. By using subjective pitches, a tonal system with simple harmonic partials (the flute) could be compared with a tonal system with complex inharmonic partials (the bell). We argue that the underlying musical scales of the bell ensemble and the flute are closely related and lie between an unequal-interval pure-system scale and the just-intonation scale. There is some evidence that a least interval of 60 or 66 cents figures in the flute scale, that both flute and bell scales include a 90-cent interval and a true (1,200-cent) octave, and that neither scale includes a 100-cent interval. Since there is a true octave, the scales cannot be cycles of fifths, and since there is no equal-temperament half-tone (100 cents), the scales cannot be equal in temperament. We conclude that the flute and Zhou bell scales are very similar if not the same. Apparently, strong cultural traditions and human perceptual constancies united to sustain a common flexible musical scale during 2,400 years.     

The psychophysiology of combat-induced post-traumatic stress disorder in Vietnam veterans

The psychophysiological responses of heart rate (HR), systolic and diastolic blood pressure, skin conductance level and forehead electromyogram were compared during: rest, mental arithmetic and combat sounds of gradually increasing intensity for five groups of Ss: Vietnam veterans with post-traumatic stress disorder (PTSD); Vietnam veterans without PTSD but with comparable levels of combat experience; Vietnam veterans with other psychiatric disorders; Vietnam-era veterans; and nonveteran phobics. HR response to low-intensity combat sounds provided good discrimination between veterans with PTSD and the other groups and seems to resemble a conditioned emotional response.     

Adolescent alcoholism in Benin City, Nigeria

The consumption of alcohol by Nigerian adolescents is investigated. Adolescence and alcoholism as applied in this study are defined, and the financial costs and physical and mental effects of alcohol use are described. The author used unobtrusive methods to gather data, visiting three nightclubs and an amusement park where alcohol is served in order to observe and interview adolescents. The findings show that adolescents begin drinking at an early age and consume large quantities of beer. The findings are consistent with those of other epidemiological studies. Finally, recommendations for controlling adolescent alcohol use are made.