Developmental changes in the internal structure of semantic categories

The present experiment was designed to examine the development of the cognitive representation of semantic categories. Response latencies on a classification task were compared for second, fourth, and sixth graders (8, 10, and 12 years of age, respectively) and college students. On each trial the subjects were presented with two pictures that represented either typical or atypical category exemplars. The two pictures were physically identical, nonidentical pictures from the same category, or pictures from different categories. One half of the trials were primed by presenting a category name in advance of the stimuli. In addition, stimulus degradation was manipulated in order to assess the locus of priming effects. A significant interaction of age × priming × typicality was found for physically identical stimuli. This interaction indicated that the nature of the internal representation of categories changed from the second graders to the adults. It was suggested that the second graders might weigh features inappropriately in generating semantic prototypes. The fact that stimulus degradation and priming did not interact at any age level for any of the match types indicates that priming affected a conceptual encoding stage rather than a perceptual encoding stage.     

Social elicitation of infant vocal behavior.

The time course and the nature of social elicitation of vocalizations in 3-month-old infants were analyzed. Adult stimulation produced an immediate and significant increase in both the rate and the percent of bursts of vocal sounds of eight infants (Experiment 1). Both response-independent and response-dependent social stimulation were effective in producing increased rates of vocalizations, but only when each of four infants could see the eyes of the adult who delivered the social stimulus (Experiment 2).     

Simple and complex mental addition across development

Students in Grades 1, 4, 7, and 10 were timed as they solved simple and complex addition problems, then were presented similar problems in an untimed interview. A manipulation of confusion between addition and multiplication, in which multiplication answers were given to addition problems (3 + 4 = 12), revealed evidence for the hypothesized interrelatedness of these operations in memory only in 10th graders. The overall pattern of results suggests a strong reliance on memory retrieval, even in the first-grade group, with discernible time differences when “procedural” knowledge of carrying is required for problem solution. The results were judged consistent with a fact retrieval model which invokes explicit procedural information when problem difficulty is high or when processes like carrying and estimating magnitudes are required. In agreement with several other reports, the overall slowing of performance to larger problems is best explained in terms of normatively defined problem difficulty or associative strength in memory.     

Mental addition in third,fourth, and sixth graders

Research on mental arithmetic has suggested that young children use a counting algorithm for simple mental addition, but that adults use memory retrieval from an organized representation of addition facts. To determine the age at which performance shifts from counting to retrieval, children in grades 3, 4, and 6 were tested in a true/false verification task. Reaction time patterns suggested that third grade is a transitional age with respect to memory structure for addition—half of these children seemed to be counting and half retrieving from memory. Results from fourth and sixth graders implicated retrieval quite strongly, as their results resembled adult RTs very closely. Fourth graders' processing, however, was easily disrupted when false problems were presented. The third graders' difficulties are not due to an inability to form mental representations of number; all three grades demonstrated a strong split effect, indicative of a simpler mental representation of numerical information than is necessary for addition. The results were discussed in the context of memory retrieval versus counting models of mental arithmetic, and the increase across age in automaticity of retrieval processes.     

Procedural knowledge versus fact retrieval in mental arithmetic: A reply to Baroody

Based on a review of reaction time studies, a model of mental arithmetic performance which emphasizes the process of fact retrieval from organized memory representations was proposed (M. H. Ashcraft, Developmental Review, 1982, 2, 213–236). In contrast to this view A. J. Baroody (Developmental Review, 1983, 3, 225–230) proposes that most mental arithmetic performance depends on procedural knowledge such as rules, heuristics, and principles. While Baroody's idea is both intriguing and potentially important, its exposition is quite vague and speculative. Without concrete suggestions as to the nature of the proposed rules and heuristics, especially for routine problems like 4 + 3 and 8 × 5, Baroody's proposal appears to be pertinent only to special cases like N + 0 and N + 1. Lacking this sort of elaboration, the alternative does not provide a useful or compelling explanation of the existing Chronometric results, and seems, at best, to be premature.     

The production and verification tasks in mental addition: An empirical comparison

We respond to A. Baroody's comment (1984, Developmental Review, 4, 148–156) with an empirical comparison of the production and verification tasks. With the exception of performance at the first grade level, the two tasks yield essentially identical conclusions. The results of an adjunct task, in which the rate of mental counting was assessed, suggest that children as young as second grade are relying on memory retrieval to a significant degree. In contrast to Baroody's speculation, there appear to be no widespread difficulties associated with results from the verification task. Furthermore, the task permits a more analytic examination of performance and underlying mental process than is afforded by the production task. We conclude by reiterating the empirical support for a model of fact retrieval, and suggesting that accessibility of the arithmetic facts is the basic factor which underlies both fact retrieval and procedural knowledge performance.     

A model of cognitive development across the life span

A model of cognitive development across the life span was proposed. A distinction was drawn between an individual's unexercised potential, which refers to the level of performance that would be expected if the individual had no exercise and/or training on the ability in question, and an individual's optimally-exercised potential, which refers to the level of performance that would be expected if the individual had optimal exercise and training. Both unexercised and optimally-exercised potential levels were proposed to increase with age up to early adulthood and decrease gradually thereafter. The region between the two types of potential, which was also suggested to increase during childhood and decrease during later adulthood, indicates the extent to which exercise and/or training can affect performance. This model was shown to be consistent with a number of different types of empirical findings.     

Facilitating cognitive performance in children: A comparison of strategy modeling and strategy modeling with overt self-verbalization

Children, 3, 4, 5, 6, 8, and 10 years old, were randomly divided into three training conditions—a strategy modeling condition, a strategy modeling with overt self-verbalization condition, and a control condition. The subjects in the two modeling conditions were given training on four cognitive tasks, a signal task, a match-to-standard task, a paired-associates task, and a twenty-questions task. A 6 (age) × 2 (sex) × 3 (treatment) × 2 (trial) analysis of variance was performed on each of the dependent variables associated with each of the four tasks. The results of these analyses indicate that both modeling conditions facilitated performance on the signal and match-to-standard tasks for all six age groups. However, the two modeling procedures facilitated performance on the paired-associates and twenty-questions tasks only in the three older age groups. Since the two modeling procedures did not differ in effectiveness, it was suggested that strategy modeling without overt self-verbalization is the more practical and efficient procedure for facilitating cognitive performance in normal children.     

Conservation training in four-year-old children

In Experiment 1 two training procedures were used to teach four-year-olds to conserve. Verbal rule instruction consisted of providing verbal rules and demonstrations of the operations referred to by the rules. Feedback consisted of providing verbal feedback contingent upon the children's responses. One week after training on conservation of number and length the children were given a posttest which included tests of conservation of number, length, and mass. Children who were given verbal rule instruction conserved significantly more on the number and length posttest problems than children who were not. However, this learning did not transfer to the mass problems, possibly because mass is not naturally acquired until some time after conservation of number and length. The feedback training procedure had no effect on conservation performance. In Experiment 2, the verbal rule instruction procedure was used to train four-year-olds on conservation of length and mass. One week after training the children were tested on both conservation of number, which is typically acquired before length and mass, and conservation of weight, which is typically acquired after length and mass, as well as on conservation of length and mass. Children who were given training conserved more on all four types of problems than children in the control group.     

Exercise, changes in aerobic capacity, and changes in self-perceptions: An experimental investigation

Subjects in an exercise training condition participated in a 10-week aerobic exercise class, whereas subjects in waiting-list control and independent control conditions did not. The results indicated that subjects in the training condition evidenced reliably greater improvements in physical fitness (aerobic capacity) and reported reliably greater improvements in their abilities and confidence in both the physical area (e.g., ability to run distances) and nonphysical area (e.g., frustration tolerance) than did subjects in the control conditions. On the other hand, improvements in physical fitness were not related to reported improvements in abilities and confidence. These findings are of interest because they indicate that some of the important personal changes that are associated with physical fitness training are not due to changes in fitness, but appear to be due to other factors (e.g., group participation and expectancies).     

The self-serving attributional bias: Beyond self-presentation

An experiment was conducted to provide empirical support for the notion that asymmetrical causal attributions for favorable and unfavorable outcomes result from a self-serving attributional bias that occurs independently of self-presentational concerns. Subjects did either well or poorly on an ego-involving test for which their performance, attributions, and evaluations of the test were either public or private. A pattern of self-serving responses for subjects' attributions and evaluations of the test was found in the private conditions, thus providing evidence of the influence of outcome favorability on individuals' perceptions of causality. Theoretical and practical implications of these finding are discussed and suggestions for future research are offered.     

The development of visual information processing skills related to reading

Literate adults can use their familiarity with specific words and their knowledge of English orthography to facilitate word recognition processes. The development of word superiority effects in visual perception was investigated in the present study using a search task with kindergarten (5.7 years old), second (8.0 years old), and fourth grade children (10.0 years old), and college students. The search task consisted of the visual presentation of a target letter followed by a three-, four-, or five-letter display. The target letter was included in the display on half the trials, and the displays were common words, orthographically regular pseudowords, and irregular nonwords. Although response times decreased with age, the three oldest groups showed similar effects for the size and structure of the displays. That is, response times increased linearly with the number of display letters, and responses were faster for word and pseudoword displays than for nonwords. The data for the kindergarten children showed evidence for the use of a different search strategy, and they did not respond differentially to the three types of displays. The results are discussed in terms of the implications for developmental models of visual search and word superiority effects in visual perception.     

The effects of aversive conditioned stimuli on the timing of unsignalled avoidance responding in rats

Rats received unsignalled avoidance training in a shuttlebox. After acquisition, classical conditioning sessions were administered. The Excitatory Group received signals paired with shock, the Inhibitory Group received signals explicitly unpaired with shock, while the Random Control Group received signals and shocks randomly in time. When subsequently superimposed on the avoidance baseline, the excitatory signal increased response rate, the inhibitory signal decreased rate and the random signal had no effect compared to signal-only control data. Unsignalled avoidance generates temporal gradients of responding; the major purpose of this study was to determine how these rate changes were reflected in the baseline temporal behavior. Very clear and simple summation rules emerged: In the presence of the excitatory signal, rats acted as if they were ahead of their actual location in the response-shock interval regardless of where the signal occurred; the inhibitory signal had the opposite effect while the random signal did not change the temporal behavior relative to signal-only control data. These results were interpreted within a motivational framework.     

Memory, acquisition, and category clustering in learning-disabled children.

In Experiment 1, single trial, immediate-free recall of learning disabled and nondisabled children was compared. The primacy effect in learning-disabled children was lower, suggesting that rehearsal or other types of elaborative encoding may be deficient in these children. In Experiment 2, acquisition of randomly presented categorical lists in a multitrial-free recall task was compared in learning disabled and nondisabled children. One-half of each group was required to learn the same number of words (34 per list), whereas list length for the other half exceeded the primacy effect of each child in immediate-free recall to the same degree. When the same number of items was learned, acquisition was slower in learning disabled than nondisabled children. When the number of items varied according to the primacy effect of each child, acquisition of both groups was similar. Clustering was lower in learning disabled than nondisabled children. In Experiment 3, multitrial-free recall acquisition of categorical lists was examined in a subject-paced task. When the number of words learned exceeded the primacy effect of each child to the same degree, trials to criterion were similar in both groups but, when the children learned the same number of items, learning-disabled children required more trials to criterion. Presentation rates were faster in learning-disabled children. Presentation rates were negatively correlated with trials to criterion and positively correlated with clustering and primacy in immediate-free recall, suggesting that study time may be taken up by clustering, rehearsal, and/or other encoding strategies. Deficient elaborative encoding may be responsible for the slower acquisition of learning-disabled children.     

Developmental changes in units of processing in reading

A visual search task was used to investigate the development of word processing skills used in reading meaningful prose. Children from the second and fourth grades and college students were asked to locate a prespecified letter, syllable, word, or category exemplar as they read through sentences. Target detection time, sentence reading time, and sentence comprehension were measured. The results provide converging evidence that whole words were the preferred units of processing during reading for all three grade levels. Reading rates for sentences in the word search condition were comparable to normal reading rates. The search for smaller units required additional processing time, but word and category search times differed only for the youngest subjects.     

On the relationship between empathy and the actor versus observer hypothesis

Subjects listened to a tape recording of a dyadic interaction. It was predicted that the observational set instructions received by the subjects (to empathize with one member of the dyad or not to empathize with this person) would create evaluation effects similar to those created for attributions of responsibility by actor-observer differences: The actor would receive credit for his positive outcome and blame for his negative outcome more when evaluated by nonempathizing observers, and the social environment would receive credit and blame for the actor's outcomes more when evaluated by empathizing observers. The predicted three-way interaction was obtained. Additional results are discussed in terms of previous empathy research.