The problem-solving strategies of kindergarten and first-grade children during discrimination learning

Kindergarten and first-grade children (6 and 7 years of age, respectively) were given specially designed discrimination tasks with introtact probes preceding each trial. One group (CON) was given the criterion task without prior training. A second group (LTL) received three pretraining tasks of the same type as the criterion task. A third group (HYP) received the same pretraining tasks, but with explicit instructions designed to teach a simple hypothesis-testing strategy. Several indices, designed to reflect the use of win-stay and lose-shift rules, as well as memory for disconfirmed hypotheses, were computed from the protocols of the criterion task. The indices for Group CON suggested that most of these children were using a guessing strategy that involved quite frequent changes in hypotheses. Moreover, many of these children restricted their hypotheses to the irrelevant cues. The indices for Group LTL revealed a spontaneous use of the hypothesis-testing strategy by nearly half of the children. The results for Group HYP indicated that over four-fifths of these children became highly efficient in the use of the problem-solving strategy.     

Verbal recoding of visual stimuli impairs mentalimagetransformations

Two experiments were carried out to test the hypothesis that verbal recoding of visual stimuli in short-term memory influences long-term memory encoding and impairs subsequent mental image operations. Easy and difficult-to-name stimuli were used. When rotated 90 degrees counterclockwise, each stimulus revealed a new pattern consisting of two capital letters joined together. In both experiments, subjects first learned a short series of stimuli and were then asked to rotate mental images of the stimuli in order to detect the hidden letters. In Experiment 1, articulatory suppression was used to prevent subjects from subvocal rehearsal when learning the stimuli, whereas in Experiment 2, verbal labels were presented with each stimulus during learning to encourage a reliance on the verbal code. As predicted, performance in the imagery task was significantly improved by suppression when the stimuli were easy to name (Experiment 1) but was severely disrupted by labeling when the stimuli were difficult to name (Experiment 2). We concluded that verbal recoding of stimuli in short-term memory during learning disrupts the ability to generate veridical mental images from long-term memory.     

A disconfirmation of the quantitative identity-quantitative equivalence sequence

Sixty-four kindergarten children received tests of quantitative identity and quantitative equivalence for the conservations of number and continuous quantity. Two types of identity trials were included: a standard version using a single stimulus, and a modified version which paralleled the equivalence task in its use of two stimuli. In addition, half of the children were asked two questions on each trial (one preceding and one following the transformation), whereas half were asked only the post-transformation question. Neither the number of stimuli used nor the number of questions asked had any effect on performance. In contrast to some previous reports, tests of quantitative identity were no easier than tests of quantitative equivalence. It was concluded that the identity-equivalence décalage, if it exists at all, is less important than previous authors have claimed.     

The effect of the temporal locus of the introtact probe on the hypothesis-testing strategies of kindergarten children

The hypothesis-testing behavior of kindergarten children in discrimination learning was studied in a factorial design with two temporal placements of introtact probes (pretrial and posttrial) and two types of pretraining (unidimensional and multidimensional). Pretrial probes consisting of a request for the child's current hypothesis were administered in a conventional manner at the beginning of each trial with the stimuli in view and prior to the choice response. Posttrial probes were administered also with the stimuli in view, but after the choice response had occurred and feedback information had been provided. Learning-to-learn experience in solving three pretraining problems was given either with unidimensional simultaneous problems or with more complex multidimensional problems like the criterion tasks. The results indicated that posttrial probes produced superior local consistency, win-stay, and lose-shift probabilities, relative to pretrial probes, for both types of pretraining. Posttrial probes, however, facilitated learning and the testing of valid hypotheses only for multidimensional pretraining. These results are consistent with the hypothesis that posttrial probes constrain the child to be locally consistent and therefore improve short-term efficiency in hypothesis testing under both pretraining conditions. However, posttrial probes produce an improvement in long-term efficiency, and therefore in learning, only when other components of a successful strategy are acquired as in multidimensional pretraining.     

Hemispheric asymmetry in memory search for four-letter names and human faces

Two memory search experiments were conducted using vertically oriented four-letter names and human faces as stimuli. Subjects were required to indicate as quickly and as accurately as possible whether or not a single probe stimulus (presented for 150 msec to either the left or right visual field) was contained in a set of 2, 3, 4, or 5 items being held in short-term memory. The probe stimuli were presented alone (clear condition) or centrally embedded in a matrix of dots (degraded condition). In Experiment 1 (involving names), a right visual field/left hemisphere advantage was obtained and pinpointed at the encoding stage rather than at the memory comparison stage of the information-processing system. For Experiment 2 (involving human faces), no hemispheric advantage was readily observed. In each experiment, both the left hemisphere and the right hemisphere employed an abstract memory comparison operation from which the effects of probe degradation have been removed. These results are discussed in terms of their implications for various models of hemispheric asymmetry.     

The effect of pretraining and feedback on the reasoning of young children

Three experiments are reported in which kindergarten and first-grade children were given one-trial multidimensional reasoning tasks that were modifications of those used by T. C. Toppino (1980, Journal of Experimental Child Psychology, 30, 496–512). In the first two experiments, the nature of the stimulus compounds (partitioned or unitary) was varied in a series of tasks of increasing complexity. First-grade children (Experiment 1) and kindergarten children (Experiment 2) performed extremely well on all of the tasks presented. Experiment 3 was designed to identify factors that contribute to these high levels of performance, relative to those obtained under the conditions used by Toppino (1980). The results indicated that a combination of feedback information and preliminary experience with simple forms of the tasks are sufficient to produce the high performance levels, and that the verbal labeling of stimulus components is not an essential constituent of the training.     

Information processing in reading-disabled and nondisabled children

Reading disabled and nondisabled children (13-14 years of age) were presented lists of 10 words each at different rates (one word per 1, 2, and 4 sec), and immediately after the last word of each list they recalled the words in any order. Recall of the first few words presented from each list (the primacy effect) was lower in reading-disabled than nondisabled children, and slower presentation rates increased the primacy effect in both groups. These findings suggest that reading-disabled children are not completely failing to use elaborative encoding but are using less effective elaborative encoding than nondisabled readers. With all presentation rates, recall of the last few words (the recency effect) was comparable in both groups, suggesting that older reading-disabled children encode and recognize the stimuli and that elaborative encoding is deficient in reading-disabled in spite of adequate stimulus encoding and recognition.     

Memory scanning by children: Meaningfulness and mediation

Two experiments were performed for the purpose of isolating factors that influence speed of memory scanning by children. The first experiment revealed an interaction involving age and type of stimulus. Young children required relatively greater time to process ambiguous stimuli. The second experiment, involving a pretraining phase designed to induce mediation, showed that preschool children scan representations more rapidly when given instructions to apply a mediator.     

The development of visual encoding and retention skills

The development of the ability to visually encode and maintain a visual stimulus was examined in a paradigm in which verbal encoding of the stimulus was prevented. The 8-, 12-, and 21-year-old subjects participated in a shadowing task during which they viewed a letter which was visually presented for 200 msec, 5 sec after the shadowing list began. On each trial subjects either reported the letter immediately after presentation or continued shadowing for 4 or 10 sec. Although results replicated those found in previous research using the paradigm, no age differences were found in recall accuracy, types of errors, or introspective reports describing perceived recall strategy. These findings suggest that even 8 year olds were able to employ a visual code and retain it for several seconds in a situation in which incentive to do so was provided.     

Factors affecting hypothesis testing in kindergarten children

In a previous experiment, the authors demonstrated that kindergarten and first-grade children can be trained to test hypotheses sequentially within the context of a discrimination learning task. The present experiment is concerned with delineating various aspects of the pretraining that contribute to the improved hypothesis-testing strategies of kindergarten children (mean CA = 71.6 months). It was found that children who have learned to anticipate an invariant cue-reward relation in such tasks manifest improved hypothesis-testing behavior, as well as improved discrimination performance, whereas children who have been trained to identify and name the various stimulus components of the discriminanda do not perform better than those without such training. It was also found that children who have had practice in shifting from an irrelevant to a relevant dimension perform better than those who have not had such experience. Moreover, children who have been given explicit instruction and training in the use of win-stay and lose-shift rules, as well as in the use of valid hypotheses, manifest strategies superior to those without such training. Finally, extensive pretraining over two sessions, administered on separate days, resulted in a marked reduction in the proportion of children who were dimensionally fixated while solving discrimination problems with two genuine dimensions.     

Integration of cardiac responses to serial stimuli after Pavlovian conditioning in rats

The expression of cardiac responses to sequences of two sounds was studied in restrained rats following discriminative trace or delay conditioning. Stimuli paired with a tail shock 10 sec later (CS1) elicited conditioned bradycardia. Unpaired or neutral stimuli (CS0) elicited mostly tachycardia. Rats did not learn to suppress responding to nonreinforced sequences with an interval of 6 sec between sounds. Responses to the second stimulus were significantly augmented following a CS1 stimulus, but not following a CS0 stimulus. Real-time summation of simple responses provided a more complete and quantitative prediction of dual responses than did resetting or facilitation. These results extend the time range over which summation may be observed from less than 2 sec to at least 16 sec. They appear to be inconsistent with models involving competition between unitary representations of stimuli in short-term memory and suggest the existence of multiple stimulus traces with independent time courses.     

Reward schedule effects in extinction: Intertrial interval, memory, and memory retrieval

Rats were trained in a runway such that partial reward occurred on Trial 1 of the day and consistent reward on subsequent massed trials (Group PRT1), or consistent reward occurred on Trial 1 of the day and partial reward on subsequent massed trials (Group PRTM). Under spaced (24-hr) extinction, Group PRT1 was more resistant to extinction than Group PRTM and under massed (1-min) extinction, Group PRTM was more resistant to extinction than Group PRT1. These findings suggest that (a) distinctive stimuli are associated with Trial 1 of the day and with subsequent massed trials, (b) these distinctive stimuli function as retrieval cues for memories, memory retrieval being independent of intertrial interval, and (c) behavior in extinction is controlled by a stimulus compound consisting of the memory of nonreward plus stimuli which accompany the memory of nonreward on rewarded acquisition trials.     

Naming and categorization in young children: III. Vocal tact training and transfer of function

Following pretraining with everyday objects, 10 children aged from 1 to 4 years were given common vocal tact training with a set of three pairs of arbitrary stimuli of differing shapes; Set 1. Nine children learned to tact one stimulus as "zog" and the other as "vek" in each pair, and all passed subsequent pairwise tests for the corresponding listener behavior to each listener stimulus (i.e., /zog/ and /vek/, respectively). The children were next trained to clap to one stimulus of Pair 1 and wave to the other, and all then showed name-consistent transfer of these behaviors to the stimuli of Pair 2 and Pair 3. Seven children also were given a test of listener responding to experimenter-modeled clap and wave gestures, respectively, which they all passed. Four of the children next participated in a category match-to-sample test for the Set 1 stimuli; all 4 passed. For each pair of two additional six-stimuli sets, Set 2 and Set 3, 3 children were trained to wave to one stimulus and to clap to the other. For each set, all 3 children showed perfect transfer of the vocal tacts trained to Set 1, and of listener behavior both to the auditory stimuli /zog/ and /vek/ and to experimenter-modeled clap and wave gestures. They also sorted the stimuli perfectly in category match-to-sample tests for Set 2, Sets 1 and 2 combined, Set 3, and Sets 1, 2, and 3 combined. The results show that even in very young children, naming is a powerful means of generating new category relations among as many as 18 arbitrary stimuli.     

Short-term memory and information processing in pigeons

Six pigeons were trained to asymptotic performance on a variable-delay matching-to-sample task in which the samples were sometimes line or color elements and sometimes line-color compounds. On compound-sample trials, the comparison stimuli were sometimes color elements and sometimes line-tilts. Sample type and delay (0, 1.5, and 4.5 sec) were varied within sessions, and sample duration (.4, 1.0, and 3.0 sec) was varied between sessions. Forgetting curves were steeper for line-tilt than for color. As sample duration increased, matching performance improved more for colors than for line-tilts, especially at delays greater than zero. Performance was better with element samples than with compound samples only on the line-tilt dimension at zero delay. Some predictions of a unitary trace growth and decay theory of pigeon short-term memory were not confirmed. A dual-code hypothesis was proposed to account for the data.     

Mechanisms of blocking by contextual stimuli

The influence of contextual stimuli on the conditioning and performance of responding to a discrete stimulus was examined in the US preexposure paradigm using both context shift manipulations and a measure of context conditioning. Four groups of rats received both repeated exposure to an electric shock US in one context (Context 1), and repeated nonshocked exposure to a second context (Context 2). Two additional groups of rats received exposure to these contexts, but never received shock presentations. Rats exposed to shock learned to escape from the stimuli of Context 1, but did not escape from the stimuli provided by Context 2. Rats not exposed to shock failed to escape from either context. All rats then received a single CER conditioning session in which four pairings of a 3-min noise CS and shock US were presented. Half the rats received those CS-US pairings in the excitatory Context 1, while the remaining rats received those pairings in the neutral Context 2. Finally, half the rats in each of the CER conditioning treatments received extinction test trials of the noise CS in Context 1, while the remaining rats received those test trials in Context 2. Thus, this design factorially manipulated the presence of excitatory or neutral contextual stimuli during both conditioning and testing of a discrete CS. In comparison with the two groups of rats never preexposed to shock alone, attenuation in acquisition of conditioned suppression observed during test trials occurred only when CER conditioning had been administered in the excitatory Context 1, and this effect was manifested when testing occurred in either the excitatory Context 1 or the neutral Context 2. These results support the model of R. A. Rescorla and A. R. Wagner (1972) (in A. H. Black & W. F. Prokasy (Eds.) Classical Conditioning II, pp. 64–99, New York: Appleton-Century-Crofts) which asserts that contextual stimuli and sicrete CSs compete for limited associative strength supportable by a given US.     

Stimulus-specific processing consequences of pattern goodness

Two issues concerning the effects of visual pattern goodness on information processing time were investigated: the role of memory vs. encoding and the role of individual stimulus goodness vs. stimulus similarity. A sequential “same-different” task was used to provide differentiation of target item or memory effects from display item or encoding effects. Experiment 1 used four alternative stimuli in each block of trials. The results showed that good patterns were processed faster than poor patterns for both “same” and “different” responses. Furthermore, the goodness of the target item had a greater effect on reaction time than did the goodness of the display item, indicating that memory is more important than encoding in producing faster processing of good stimuli. Effects of interstimulus similarity on processing time were minimal, although isolation of good stimuli in a similarity space could explain many of the results. Experiment 2 replicated the results of Experiment 1, despite the fact that differences in similarity space had been minimized by using only two alternative stimuli in each block. In addition, the speed of processing a “same” pair was essentially independent of the particular alternative stimulus in a block. These results suggest that in this task, there is a processing advantage for good stimuli that is stimulus specific, with the effect operating primarily in memory.     

Flexibility of working memory encoding in a sentence–picture–sound verification task

Dual-process accounts of working memory have suggested distinct encoding processes for verbal and visual information in working memory, but encoding for nonspeech sounds (e.g., tones) is not well understood. This experiment modified the sentence–picture verification task to include nonspeech sounds with a complete factorial examination of all possible stimulus pairings. Participants studied simple stimuli–pictures, sentences, or sounds–and encoded the stimuli verbally, as visual images, or as auditory images. Participants then compared their encoded representations to verification stimuli–again pictures, sentences, or sounds–in a two-choice reaction time task. With some caveats, the encoding strategy appeared to be as important or more important than the external format of the initial stimulus in determining the speed of verification decisions. Findings suggested that: (1) auditory imagery may be distinct from verbal and visuospatial processing in working memory; (2) visual perception but not visual imagery may automatically activate concurrent verbal codes; and (3) the effects of hearing a sound may linger for some time despite recoding in working memory. We discuss the role of auditory imagery in dual-process theories of working memory.     

The value of being imitated

Theories and research on the topics of attraction, conformity, and imitation support the view that the relational stimulus arising from being imitated serves a reinforcing function. To examine this possibility, 48 preschool children performed a task in which some neutral stimuli were repeatedly associated with an adult's matching the behavior of the subject, and other neutral stimuli were associated with the same adult's mismatching the behavior of the subject. Preference for the stimuli associated with being matched was greater at the end of training than earlier, and the overall preference for the matched stimuli exceeded chance. The results are considered in terms of the thesis that similarity arising from being imitated served a reinforcing function and the thesis that response strategies were adopted by the children.     

Cardiac deceleration in newborns: habituation, dishabituation, and offset responses.

Twenty healthy, 1–4 day-old infants were selected from a sample of 135 neonates on the basis of alertness during testing. The infants were presented mild intensity colored light with gradual onset and offset while heart rate was monitored. Half the infants received six exposures to blue light followed by two exposures to blue-green light, whereas remaining subjects received colors in reverse order. Stimulus duration was 20 sec and variable periods between stimuli averaged 30 sec. Results of trend analysis of variance of the second-by-second cardiac data indicated that for infants older than the median age, the decelerative responses to both stimulus onset and offset were significant. Further, these subjects' onset decelerations significantly habituated within the six stimulus repetitions and significantly dishabituated with change in the stimulus color. Offset decelerations incremented over habituation trials and decremented with change in stimulus color. Responses of younger subjects were more variable which probably reflects their less complete recovery from the effects of maternal medication and the birth process.