Choice as a function of local versus molar reinforcement contingencies.

Rats were trained on a discrete-trial probability learning task. In Experiment 1, the molar reinforcement probabilities for the two response alternatives were equal, and the local contingencies of reinforcement differentially reinforced a win-stay, lose-shift response pattern. The win-stay portion was learned substantially more easily and appeared from the outset of training, suggesting that its occurrence did not depend upon discrimination of the local contingencies but rather only upon simple strengthening effects of individual reinforcements. Control by both types of local contingencies decreased with increases in the intertrial interval, although some control remained with intertrial intervals as long as 30 s. In Experiment 2, the local contingencies always favored win-shift and lose-shift response patterns but were asymmetrical for the two responses, causing the molar reinforcement rates for the two responses to differ. Some learning of the alternation pattern occurred with short intertrial intervals, although win-stay behavior occurred for some subjects. The local reinforcement contingencies were discriminated poorly with longer intertrial intervals. In the absence of control by the local contingencies, choice proportion was determined by the molar contingencies, as indicated by high exponent values for the generalized matching law with long intertrial intervals, and lower values with short intertrial intervals. The results show that when molar contingencies of reinforcement and local contingencies are in opposition, both may have independent roles. Control by molar contingencies cannot generally be explained by local contingencies.     

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.     

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.     

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.     

One-trial object recognition by rats

Four experiments examined the ability of rats to solve problems analogous to those used with primates, where they were required to remember an object seen on a single trial. In the first experiment, rats were rewarded for selecting the novel of two goal boxes in a Y-maze (nonmatching). Different pairs of goal boxes were used for every trial within a session in order to increase the salience of the positive stimulus and to exclude the use of odour trails. The animals rapidly learnt this one-trial object recognition task and performed well above chance after retention intervals as long as 120 sec. A control experiment confirmed that the rats could not use spatial cues to solve the task. A third experiment showed that rats could also learn to select the familiar of two boxes in a one-trial test of object matching. In the final experiment the rats were unable to acquire a win-stay/lose-shift strategy when tested in a comparable manner.     

Rats acquire spatial learning sets

This experiment was designed to examine the development of a spatial learning set in rats and some of the variables influencing the retention of individual problems. The apparatus was a plus maze. At the beginning of each test, the rat was put on two arms, each in a different place. Food was present in one of the arms, but not in the other. The rat was then given a choice between these two places; the correct response was to return to the place that previously contained food (win-stay, lose-shift, response-reinforcement contingency). Fifty different two-choice spatial discriminations were given, each in a different location. At the end of testing, the mean percentage of correct responding for the first choice between the two places was 83%. Control procedures showed that the discriminative stimuli were distal, extramaze spatial stimuli. Variations of the procedure examined the influence of proactive interference and temporal delay on the memory for each discrimination. These results demonstrate that rats can develop a spatial learning set and provide new information about the characteristics of the memory underlying learning sets.     

Visual discrimination learning and strategy behavior in the fat-tailed dunnart (Sminthopsis crassicaudata)

Fat-tailed dunnarts (Sminthopsis crassicaudata) were trained on visual discrimination learning-set, reversal-set, and spatial delayed-alternation tasks. The learning set involved 36 2-way black-and-white pattern discriminations and 5 probe reversals. Ten reversals of a black-and-white pattern discrimination were followed by 5 novel tasks. Spatial alternation was tested at delays up to 20 s. Learning-set and reversal-set formation, including 1-trial learning and spontaneous transfer from learning set to reversals and vice versa, was found. Learning-set-experienced dunnarts showed no retention of previously learned tasks 1 week after testing but demonstrated consistently high Trial 2 performance, indicating the retention of a response strategy. Delayed-alternation tasks were learned up to 10-s delays. These results provide the first evidence of a visually guided "win-stay, lose-shift" strategy in a marsupial.     

计数与匹配:5~6岁儿童量比较策略的发展特点

选取56名5~6岁儿童,采用计算机呈现刺激的方式,实现了刺激的动态呈现来模拟策略的使用过程,并通过对于被试正确率和反应时的考察确定了每一名被试使用计数和匹配策略进行量比较的特点。结果表明:(1)与计数策略相比,儿童对于匹配策略的掌握更加成熟,5岁和5岁半组被试使用匹配策略解决量比较问题的正确率更高;(2)在已经掌握计数和匹配两种策略的情况下,仍有一部分儿童更倾向于使用匹配策略来解决量比较问题。     

Heterogeneity of strategy use in the Iowa gambling task: A comparison of win-stay/lose-shift and reinforcement learning models

The Iowa gambling task (IGT) has been used in numerous studies, often to examine decision-making performance in different clinical populations. Reinforcement learning (RL) models such as the expectancy valence (EV) model have often been used to characterize choice behavior in this work, and accordingly, parameter differences from these models have been used to examine differences in decision-making processes between different populations. These RL models assume a strategy whereby participants incrementally update the expected rewards for each option and probabilistically select options with higher expected rewards. Here we show that a formal model that assumes a win-stay/lose-shift (WSLS) strategy—which is sensitive only to the outcome of the previous choice—provides the best fit to IGT data from about half of our sample of healthy young adults, and that a prospect valence learning (PVL) model that utilizes a decay reinforcement learning rule provides the best fit to the other half of the data. Further analyses suggested that the better fits of the WSLS model to many participants’ data were not due to an enhanced ability of the WSLS model to mimic the RL strategy assumed by the PVL and EV models. These results suggest that WSLS is a common strategy in the IGT and that both heuristic-based and RL-based models should be used to inform decision-making behavior in the IGT and similar choice tasks.     

Superstitious responding and frequency matching in the positive bias and gambler’s fallacy effects

Three studies showed that success in predicting outcomes of a random binary series was associated with the positive bias effect, whereas failure was associated with the gambler’s fallacy effect. Moreover, success increased confidence and failure decreased it. Although explicit instructions that the source generated random output increased the likelihood of predicting an alternation in the series, these instructions had no effect on the relationships between success and the positive bias effect, and failure and the gambler’s fallacy effect. Importantly, intuitions about the randomness or nonrandomness of the source, assessed immediately prior to each trial, did not influence this interaction. These results suggest that people used a win-stay strategy, but that sensitivity to run length counteracted the corresponding lose-shift tendency. The data support a memory-based explanation of the gambler’s fallacy effect, consistent with the account from local representativeness, but the positive bias effect may be an instance of human superstitious responding.     

Rules versus cognitive structure as bases for children's performances on probability problems

The present study compared two hypotheses about children's solutions to Piaget and Inhelder's (1975) two-set alternative choice probability problems. The first was that children follow rules that specify a temporally ordered sequence of tests and decisions (Siegler, 1981). One prediction of rules is that children who know strategies that combine variables within sets (e.g., ratio or subtraction strategies) will only use them on problems that require such strategies (conflict problems), whereas lower level (nonconflict) problems will be solved by directly comparing the values of variables between sets. The second hypothesis was that once children develop knowledge of within-set solutions to probability problems, they apply them to both conflict and nonconflict problems. The results supported the latter hypothesis. The majority of children who solved conflict problems using within-set strategies explained at least one nonconflict problem by referring to within-set combinations. Results were discussed in terms of their implications for cognitive development and for instruction.     

Factors influencing the use of transparency in children's drawing

When young children draw a scene in which one object partially occludes another, they often depict hidden features of the occluded object by rendering the nearer object transparent. This may signify a motive to produce drawings that are informative. Three experiments are reported in which a simple paradigm is employed to consider this possible basis of transparency drawing. Experiment 1 established a gradual decrease in the use of this device across the 5–7-year age range. Its occurrence could not be ascribed to a simple lack of graphic skill and it was not readily inhibited by stronger perceptual marking of scene boundaries. The extent to which children were purposefully producing informative drawings was evaluated in Expts 2 and 3. Because an increase in occluded information actually served to inhibit transparencies, it is argued that they need not reflect such a communicative attitude. An alternative account is proposed whereby drawing decisions are guided, sometimes inappropriately, by the structure of cognitive representations children form of scenes. Transparencies signify a failure to anticipate certain graphic ambiguities thereby generated. However, they may be inhibited if the geometry of a particular scene forces the child to confront such ambiguity at the outset of drawing.     

What Latina Mothers Think of Evidence-Based Parenting Practices: A Qualitative Study of Treatment Acceptability

Parent training has great potential to alter the developmental trajectories of young Latino children with or at risk for behavior problems. However, traditional parent training programs may seem culturally irrelevant or inappropriate to Latino parents as they promote practices that are based on white, middle class standards. The current study of treatment acceptability used focus group and key informant interviewing methodology to investigate Latina mothers’ views on the causes of young children's misbehavior and the acceptability of evidence-based parenting strategies. The sample consisted of Spanish- and English-speaking Latina mothers of 3- to 6-year-olds recruited from day-care centers and preschools in New York City. Focus groups were conducted with 34 mothers, and key informant interviews with 5 mothers whose children had behavior problems. Results showed that the most commonly viewed causes of child misbehavior were child temperament, fighting in the home, and negative peer influence. Mothers found some evidence-based parenting strategies acceptable (e.g., the use of praise, social rewards) and others objectionable (e.g., selective ignoring in pubic situations, the elimination of spanking). For some strategies, there was little consensus on its acceptability (e.g., time-out). Taken together, results highlight the critical need for aligning parent and clinician goals at the outset of treatment, and of including a strong psychoeducational component in parent training programs because not all of its components are consistent with Latino cultural norms and beliefs.     

Children’s Knowledge of Ellipsis Constructions in Mandarin Chinese

This study investigated 4-year-old children’s knowledge of the structural constraints on ellipsis constructions in Mandarin Chinese, focusing on the structural difference between verb phrase (VP) ellipsis and null object constructions. In Mandarin Chinese, if the antecedent clause of a VP-ellipsis structure contains an adverbial modifier, this adverbial modifier must be recovered at the elided site in the second clause. However, if the antecedent clause of a null object construction contains an adverbial modifier, the reconstruction of this adverbial modifier at the elided site is not necessary. Two experiments were conducted to examine whether young Mandarin-speaking children are sensitive to this structural difference between the two ellipsis constructions. The results show that children exhibited adult-like performance in both experiments. This is evidence that young Mandarin-speaking children have knowledge of the structural difference between VP-ellipsis and null object constructions with regard to adverbial recovery. We interpreted the findings in conjunction with previous research as evidence that children’s knowledge of the structural constraints on ellipsis constructions is innately specified.     

On the role of hippocampal protein synthesis in the consolidation and reconsolidation of object recognition memory

Upon retrieval, consolidated memories are again rendered vulnerable to the action of metabolic blockers, notably protein synthesis inhibitors. This has led to the hypothesis that memories are reconsolidated at the time of retrieval, and that this depends on protein synthesis. Ample evidence indicates that the hippocampus plays a key role both in the consolidation and reconsolidation of different memories. Despite this fact, at present there are no studies about the consequences of hippocampal protein synthesis inhibition in the storage and post-retrieval persistence of object recognition memory. Here we report that infusion of the protein synthesis inhibitor anisomycin in the dorsal CA1 region immediately or 180 min but not 360 min after training impairs consolidation of long-term object recognition memory without affecting short-term memory, exploratory behavior, anxiety state, or hippocampal functionality. When given into CA1 after memory reactivation in the presence of familiar objects, ANI did not affect further retention. However, when administered into CA1 immediately after exposing animals to a novel and a familiar object, ANI impaired memory of both of them. The amnesic effect of ANI was long-lasting, did not happen after exposure to two novel objects, following exploration of the context alone, or in the absence of specific stimuli, suggesting that it was not reversible but was contingent on the reactivation of the consolidated trace in the presence of a salient, behaviorally relevant novel cue. Our results indicate that hippocampal protein synthesis is required during a limited post-training time window for consolidation of object recognition memory and show that the hippocampus is engaged during reconsolidation of this type of memory, maybe accruing new information into the original trace.     

Scientific reasoning in early and middle childhood: The development of domain‐general evidence evaluation,experimentation, and hypothesis generation skills

According to Klahr's (2000, 2005; Klahr & Dunbar, 1988) Scientific Discovery as Dual Search model, inquiry processes require three cognitive components: hypothesis generation, experimentation, and evidence evaluation. The aim of the present study was to investigate (a) when the ability to evaluate perfect covariation, imperfect covariation, and non‐covariation evidence emerges, (b) when experimentation emerges, (c) when hypothesis generation skills emerge, and (d), whether these abilities develop synchronously during childhood. We administered three scientific reasoning tasks referring to the three components to 223 children of five age groups (from age 4.0 to 13.5 years). Our results show that the three cognitive components of domain‐general scientific reasoning emerge asynchronously. The development of domain‐general scientific reasoning begins with the ability to handle unambiguous data, progresses to the interpretation of ambiguous data, and leads to a flexible adaptation of hypotheses according to the sufficiency of evidence. When children understand the relation between the level of ambiguity of evidence and the level of confidence in hypotheses, the ability to differentiate conclusive from inconclusive experiments accompanies this development. Implications of these results for designing science education concepts for young children are briefly discussed.     

STIMULUS OVERSELECTIVITY IN LEARNING DISABLED CHILDREN

Stimulus overselectivity, a phenomenon exhibited by autistic and institutionalized retarded individuals, was examined in mildly handicapped and nonhandicapped public school children. Subjects were 16 young, educable mentally retarded, 16 learning disabled, 15 nonhandicapped first- and second-graders, and 16 older, educable retarded students. The children were trained on a 3-component visual discrimination task and then tested on individual elements to determine which element or elements were controlling subject responses. Nine of the young educable mentally retarded children and eight of the learning disabled students showed some overselectivity. The majority of overselective retarded children were controlled by only one of the three components of the training cue, whereas the majority of the overselective learning disabled children responded to the discrimination task on the basis of two of the three components. No overselectivity was exhibited by the nonhandicapped students. All three cue components were also functional in controlling the responding of 14 of the 16 older retarded students, but two children were under the control of only one cue. The research indicated that in terms of overselectivity, learning disabled children respond more like young, mildly retarded children than they do like nonhandicapped ones. The demonstration of stimulus overselectivity in a sizable portion of a learning disabled sample may have implications for a more empirically based approach to this handicapped population.     

Object identification in preschool children and adults

We introduce computer-based methodologies for investigating object identification in 3- to 5-year-old children. In two experiments, preschool children and adults indicated when they could identify degraded pictures of common objects as those pictures either gradually improved or degraded in clarity. Clarity transformations were implemented in four ways: blurring, decreasing the picture's physical size, decreasing the pixel signal-to-noise ratio, and cropping. In Experiment 1, all age groups correctly identified objects at a more degraded state when those objects began moderately, as opposed to very, degraded and then clarified. This finding supports the notion that previous perceptual hypotheses interfere with object identification (i.e. the perceptual interference effect). In Experiment 2, children, but not adults, overestimated their ability to recognize objects in a degraded state when the object's identity was given to them beforehand. This suggests that for young children knowledge of the object's true identity cannot be ignored when evaluating their current perceptions. This is the first demonstration of the perceptual interference effect in children. We discuss both methodological and theoretical implications of the findings for research on object perception and theory of mind.     

Win-stay behaviour in the rat

The Law of Effect dictates that animals will repeat the just-reinforced response “win-stay”, and yet there have been apparent violations of this by rats running for food in mazes, in the form of “win-shift” behaviour. Four experiments analysed the conditions determining win-stay and win-shift behaviour. All the experiments employed a schedule in which reinforcement was distributed across two choices, and in which the probability of reinforcement for the first response after previous reinforcement was equivalent for the two options. Despite this lack of programmed differential reinforcement, rats showed a significant win-stay tendency in Experiment 1, with no spatial bias. Experiments 2 and 3 used respectively a Y-maze and an operant chamber in which responding required a return to a central choice point. In both situations, significant win-shift behaviour resulted initially, at relatively high frequencies of reinforcement, but this win-shift changed to significant win-stay over many sessions, and with intermittent reinforcement. Experiment 4 introduced explicitly non-reinforced trials and demonstrated a “lose-shift” tendency, parallel to win-stay. Possible artefacts underlying win-stay and win-shift behaviour are rejected, and various mechanisms for these effects, including theories of optimal choice and associative learning, are discussed.     

Quantifiers and question answering in young children

Two hypotheses were tested about how young children answer questions with the quantifiers all and some: (a) that children use syntactic cues in determining which noun phrase is quantified, and (b) that children evaluate a some-statement as part of evaluating an all-statement. To test these hypotheses, the same group of 60 4- to 7-year-olds were asked four contrasting types of quantitative questions. The results indicated that children can use syntactic cues under some presentation conditions. However, there was no evidence for an asymmetry between the all-and some-questions. A model of how young children might answer quantitative questions was then considered.