Encoding variability and organization in free recall

Measures of category clustering and subjective organization are well-established predictors of performance in free recall tasks. The present studies demonstrate that a measure of encoding variability affords equally powerful and independent prediction of free recall performance. They also illustrate an interaction between encoding processes and organizational activity. In Experiments 1 and 2, the independent contributions of organization and encoding variability are demonstrated in categorizable and uncategorizable lists and in subjects whose recall is expected to increase (adults) or decrease (children) as a function of more varied encodings across trials. In Experiment 3, a category labeling procedure is used to demonstrate that the negative relationship between encoding variability and recall can be reversed by inducing adult-like organizational activity in children.     

Context and companion's behavior as determinants of cooperation and competition in school-age children

Information about the social context and a companion's actions were studied as determinants of cooperation and competition in middle childhood. In Experiment 1, first-, third-, and fifth-grade children were told that they would play a board game with another same-age, same-sex child (actually a bogus companion). The experimenter's instructions established shared rewards or winner-take-all as outcome conditions. Preprogrammed responses—100% cooperative or 100% competitive—provided information about the companion's actions. Results revealed that the companion's responses alone determined cooperation and competition among the first graders. Third graders used both types of information. Fifth graders, however, demonstrated a bias to respond cooperatively whenever a cooperative cue was present. In Experiment 2, first-grade subjects were given extra rehearsal of the game strategies, a scorekeeping procedure for use during the game, or a combination of the two. Results indicated that, under these conditions, younger subjects were able to use the instructions about reward distribution as well as the companion's actions in guiding their social behavior.     

From response-set to prediction hypotheses: Rule acquisition among preschoolers and second graders

It was proposed that prediction hypotheses do not emerge full blown in the repertoire of the young child. Instead, the component units out of which predictions are consolidated (win-stay, lose-shift) are acquired independently and at different rates. The young child's behavior is at first dominated by response sets in which the win and lose components involve the same action (win-stay, lose-stay or win-shift, lose-shift). The components of response sets must be separated and coordinated with task-relevant information before appropriate components are consolidated to yield prediction hypotheses. A combination of learning-set and blank-trial procedures was used to evaluate this conception with preschoolers (mean CA = 4:1) and second graders (mean CA = 7:6). Results revealed that children of both age levels exhibited response patterns that corresponded to hypotheses in most of their probes (.89 to. 98). The striking finding was the relative weakness of win-stay on object cues at the outset of acquisition, particularly among the younger children. In contrast. lose-shift object was strong from the outset among children of both age levels. Once the two components (win-stay object, lose-shift object) were consolidated, the resulting scheme was durable, in that transfer to more complex problems was nearly perfect. Children who did not achieve criterion (in 70 problems) failed because they exhibited mostly position hypotheses and/or because the strength of win-stay object remained weak throughout all sessions.     

Algorithms for processing spatial information

Pairs of stimuli taken from a psychometric measure of spatial aptitude were shown to 9-year-olds, 13-year-olds, and adults. The stimuli in pairs were (a) either identical or mirror images, and (b) presented in orientations that differed by 0-150 degrees. Individuals judged, as rapidly as possible, if the stimuli in a pair would be identical or mirror images if presented at the same orientation. In Experiment 1, in which the stimuli were letter-like characters, at all ages most persons solved the problems using an algorithm in which an individual encodes the stimuli in working memory, mentally rotates one stimulus to the orientation of the other, compares them to determine if they are identical, and responds. In Experiment 2, the stimuli were multielement flags; here, the modal algorithm for both 9- and 13-year-olds differed from the previously described algorithm in that if the comparison process revealed that the stimuli were dissimilar, individuals did not respond immediately, but continued processing until a self-imposed deadline was reached. Among adults, the modal algorithm was the same one used in Experiment 1. Results are discussed in terms of the roles of encoding in contributing to the use of a particular algorithm.     

Proofreading errors in good and poor readers

Seven-year-old children classified as good and poor readers carried out a proofreading task on two passages varying in level of difficulty. Misspellings were introduced by transposing two adjacent letters in the work "the," other three-letter words, and longer words. While both groups of readers were able to identify the correct spelling of the misspelled words on a spelling test, poor readers made significantly more proofreading errors. Word length had a significant effect on performance, indicating that sensitivity to word configuration is important for successful proofreading. The pattern of proofreading errors did not reflect underlying differences which might relate to strategies used by the two groups in normal reading. The results are compared with those from other proofreading and letter detection experiments in order to highlight methodological implications when such tasks are used to verify hypotheses concerned with normal reading strategies.     

Asymmetry of perception in free viewing of chimeric faces

We have devised a new free-vision task to index functional cerebral asymmetry for processing facial characteristics. Confirming its sensitivity to properties of lateralized hemispheric functions, left- and right-handers were clearly differentiated on this task with respect to several aspects of performance that conform with known differences between handedness groups in hemispheric asymmetry. Additionally, there were highly reliable and stable individual differences in perceptual asymmetries within handedness. Analyses of items in the task revealed that most of the differences between items in the asymmetries they elicited were random.     

Hemisphere functioning and motor imitation in autistic persons

Previous research has found that a high proportion of autistic individuals exhibit an atypical pattern of hemispheric specialization suggestive of impaired left hemisphere functioning: namely, right hemisphere dominance for both verbal and visual-spatial processing. Studies of brain-damaged persons have suggested that the left hemisphere is specialized for the use of nonverbal gesture. Since a major characteristic of autism is an impairment in the use of gesture, it was predicted that autistic persons would also show atypical hemispheric specialization for motor imitation. To test this hypothesis, hemispheric activation was measured using EEG recordings of alpha rhythm in autistic and matched normal control subjects during four motor imitation tasks. Autistic subjects showed significantly greater right hemisphere activation during the imitation tasks, than normal subjects. This pattern was particularly evident in younger autistic subjects and during oral, rather than manual, imitation tasks.