Effects of perceptual salience on the matrix task performance of four- and six-year-old children.

The effects of salience on 4- and 6-year-old children's ability to classify multiplicatively was investigated. A rank-ordered salience hierachy consisting of 3 dimensions was first assessed for each S. Several weeks later half the Ss of each age group were presented with a series of 9 3 times 3 matrix problems consisting of values from 2 dimensions ranked high in salience. The remaining half received identically structured matrices consisting of values from 1 highly salient dimension and of others from a dimension ranked low in salience. The goal in each problem was to select that compound stimulus from a set of alternatives that appropriately filled an empty cell in the matrix. Prior to the matrix problems, half the Ss in each matrix condition received sensitization training designed to increase the salience of the relevant dimensions in the matrix problems. The results showed that the pre-assessed salience of the relevant dimensions affected matrix solution in that more accurate performance was associated with those problems with both relevant dimensions relatively high in salience than those with one high and one low. Although the older Ss solved more problems, the evidence for coordination in the younger Ss was clear. No effects of sensitization training were found.     

Reversal of visual discrimination problem and differential frustration effects in dominant and submissive rats

Two experiments are reported comparing performance in dominant and submissive rats as determined by a food-competition procedure. Ss in Experiment I were either trained to criterion or overtrained before being reversed on a visual discrimination task. Although the two groups did not differ significantly in learning the initial task, the dominant Ss were significantly slower on reversal than the submissives. Experiment II, which utilized a tandem runway, showed that when the reinforcer which maintained the running response was not available in the first goalbox, submissive rats responded with a greater increase in running speed in the second runway than dominant rats. These findings were discussed as reflecting motivational differences between dominant and submissive rats.     

Radial localization of odors by human newborns.

To study sensitivity to radial location of an odor source, 20 human newborns, ranging from 16 to 130 hours of age, were presented with a small amount of ammonium hydroxide. The odor source was placed near the nose slightly to the left or right of midline, with its position randomized over repeated trails. Direction of headturn with respect to the odor location and diffuse motor activity were scored from the videotape recordings of the newborns' behavior. It was found that as a group, the newborns turned away from the odor source more frequently than they turned toward it. The tendency to turn away from the odor was stronger in infants who displayed less motor activity after the response. Newborns also exhibited a right bias in the direction of the head movements. It is concluded that a spatially appropriate avoidance response is present in the neonate and that the newborn is innately sensitive to the radial location of an odor.     

Do infants see emotional expressions in static faces?

To determine whether young infants discriminate photographs of different emotions on an affect-relevant basis or on the basis of isolated features unrelated to emotion, groups of 17-, 23-, and 29-week-olds were habituated to slides of 8 women posing either Toothy Angry, Nontoothy Angry, or Nontoothy Smiling facial expressions and were then shown 2 new women in the familiarized expression and in a novel Toothy Smiling expression. At all 3 ages, recovery to the novel Toothy Smiling faces occurred only after habituation to Nontoothy faces (whether smiling or angry), not after habituation to Toothy Angry faces, indicating that infants had been responsive to nonspecific features of the photographs (presence or absence of bared teeth) rather than to affectively relevant configurations of features. In a second experiment, 2 older age groups (35 and 41 weeks) also proved to be insensitive to affect-related aspects of still faces, though more so for angry than for happy expressions. It is suggested that the young infant's difficulty in extracting emotional information from static stimuli may be attributable to the absence of the critical invariants (dynamic, multimodally specified) that characterize naturalistic expressions of emotion.