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.     

Situational Cues and Crime Reporting: Do Signs Make a Difference?1

Two field studies were conducted to assess the effect of signs describing how to report a shoplifting on bystander intervention to a staged theft. In the first study, signs providing directions and one of three rationales for reporting had a small effect on attitudes toward reporting and no effect on intervention. In the second study, a definition of the situation as a shoplifting by a confederate had a strong influence on subjects reporting, but presence or absence of signs describing how to report had no impact. Differences between interpersonal and nonpersonal influences are described, and implications for informational campaigns to increase crime reporting are discussed.     

Ratings of the auditory and visual similarity of consonants: Implications for research

A set of rating data was collected which compared the visual similarity of consonants to the auditory similarity of the same letters. Analysis of the rating patterns raises important questions about the use of similarity data in drawing conclusions about mode of memory coding in a variety of situations.     

Vowel recognition: Inferences from studies of forward and backward masking

The recognition of brief vowels was studied in forward and backward masking tasks. In a series of experiments in which both target and mask parameters were systematically varied, two populations of subjects were identified. The majority (Nonmaskers) evidenced little masking at any interstimulus interval, while relatively fewer subjects (Maskers) evidenced backward masking (but not forward masking) over a 100-200 ms interval. Increasing target set size systematically increased masking for the Maskers but not for the Nonmaskers. Adding white noise to the targets increased the extent of masking for both groups. These results suggest (1) that masking does not impose a substantive constraint on vowel perception in running speech, and (2) that multiple strategies may exist for vowel recognition.     

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.     

THE GENERALIZATION EFFECTS OF PARENT TRAINING ACROSS STIMULUS SETTINGS

Five parents of nonverbal children were trained in two home settings to modify antecedents and consequences to their children's vocalizations. Generalization effects of the parent training on both the parent's and children's behaviors under different stimulus conditions were investigated using multiple-baseline designs. Increases in parent prompting and reinforcing their children's vocalizations generalized only minimally to a new setting in the home where parent training had not occurred. Child increases in vocalizations produced by the parents in the training settings did generalize to this new setting in the home. There was minimal generalization of child vocalizations to a free-play setting at school. In a formal speech session conducted by a behavior specialist at school, only one child showed definite increases in acquisition rate as a function of the parents starting to train the sound at home.     

The use of visual and name codes in scanning and classifying colors

The effect of incongruent color words on speed of classifying ink colors was measured in visual scanning tasks and in card sorting tasks. In both cases, little or no interference effects were noted when the classification allowed focusing on a single ink color or a set of highly similar colors (adjacent hues). Substantial interference occurred when the task required grouping of three dissimilar colors (nonadjacent hues). These findings suggest that the relative efficiency of name and visual codes in making perceptual classifications is largely dependent upon the memory requirements imposed by the task.     

A sensitive period for the acquisition of a nonnative phonological system

Immigrants who had learned English at various ages and who had been in the United States for various amounts of time were judged for degree of accent in English. It was found that age at arrival was a strong predictor of degree of accent, while length of stay had very little effect. Other practice and motivational factors were related to accent only by virtue of their correlation with age at arrival. It was suggested that a sensitive period exists for the acquisition of a nonnative phonological system.This article was adapted from a doctoral dissertation for the Department of Psychology and Social Relations, Harvard University, 1973 (unpublished), which was supported by NSF Grant No. GS-36263 and the Radcliffe Institute.