Differences in the search rate of children and adults in short-term memory

When people recognize a test item as belonging or not belonging to a previously presented set, recognition latency increases with the number of items in the set. Although some evidence suggests otherwise, it is currently held that the rate of this increase is the same for children and adults. In contrast, the present experiments indicated a much slower search rate for second graders (mean age = 7.33 years) than for seventh (mean age = 12.50 years) and twelfth graders (mean age = 17.25 years). Moreover, search rate for second graders was invariant under instructions which did or did not emphasize speed and with presentation of the memory set in either the auditory or visual modality. Experiment II showed that the slow search rate for children was not due to differences in encoding between children and adults.     

Crowding: Effects of Group Size,Room Size,or Density?

The separate effects of group size, room size, and density (space per person) were investigated for subjects responding interactively or coactively to perceptual and cognitive tasks. The major findings are that crowding has greater effects on "feelings" and "interpersonal perceptions" than on task performance. Where crowding did have effects, they appeared to be mediated more by group size and, to some degree, room size than by density, especially for males. Female subjects appeared somewhat more density oriented than male subjects.     

Periodicity pitch perception and its upper frequency limit in cats

We have established a procedure for behavioral assessment of periodicity pitch perception in the cat. This procedure requires the training of cats to make a differential response to two different pure tones, and then testing for the transfer of learning when complex stimuli known to produce periodicity pitch sensations in humans are substituted for the pure tones. Complex stimuli consisted of three to five harmonically related frequencies of the same amplitude and phase. Eight cats were the subjects of these experiments. Two of them were controls. It is demonstrated here that cats do perceive periodicity pitch. We also used this procedure to measure the upper frequency limit of periodicity pitch perception for two cats. The frequencies tested were 100, 200, 300, 400, 600, 800, 900, and 1,200 Hz. The data indicate that the upper frequency limit of periodicity pitch perception in the cat is on the order of 600 to 800 Hz. There is a trend of decreasing prominence of the perception of periodicity pitch as the component frequencies are increased. These results are parallel to the human psychophysical data.