Improving time discrimination in children and adults in a temporal bisection task: The effects of feedback and no forced choice on decision and memory processes

In children aged 5 and 8 years old as well as in adults, Experiment 1 tested the effect of feedback on temporal performance using a bisection task. Experiment 2 added a no-forced-choice condition by giving the participants the possibility of responding “I don't know”. The results of Experiment 1 showed that providing feedback increased the bisection point value (point of subjective equality) in all age groups and increased sensitivity to time in the youngest children. The results of Experiment 2 showed that the proportion of “I don't know” responses peaked at the probe duration close to the arithmetic mean of the two anchor durations and decreased as the distance from this central value increased in both the adults and the 8-year-olds. In the 5-year-olds, the proportion of “I don't know” responses was lower and remained constant whatever the probe duration values. Unlike in the youngest children, giving the adults and the 8-year-olds the opportunity to respond “I don't know” increased their sensitivity to time. The modelling of our data suggests that providing feedback in a temporal bisection task affects both the memory and the decision processes. However, whereas the feedback-related effect had a similar effect on decision processes across the age groups, it had an opposite effect on memory processes in the 5-year-olds and the older participants, decreasing the variability of the memory representation of the anchor durations in the former while increasing it in the latter. Finally, in bisection, feedback only improved temporal performance when the memory for duration was imprecise as in the case of the children.     

Adaptive memory: longevity and learning intentionality of the animacy effect

The animacy effect—the finding that animates are better remembered than inanimates—is proving to be a robust empirical phenomenon. Considering the adaptiveness of the animate advantage, one might expect it to remain after long retention intervals and also to be present irrespectively of an intention to learn. The present study explores these two aspects. Different groups of participants learned (intentional learning) or rated the pleasantness (incidental learning) of animate and inanimate words; memory was tested immediately or after a 48?h delay. A significant animacy effect was obtained after both retention intervals and in both learning conditions. Two significant interactions revealed a larger animacy effect, as well as a larger effect of the retention interval, when learning was incidental. Our findings reinforce the robustness of the animacy effect and provide some insight into possible proximate mechanisms of the effect.     

Vocabulary learning in primary school children: Working memory and long-term memory components

The goal of this study was to investigate which working memory and long-term memory components predict vocabulary learning. We used a nonword learning paradigm in which 8- to 10-year-olds learned picture-nonword pairs. The nonwords varied in length (two vs. four syllables) and phonology (native sounding vs. including one Russian phoneme). Short, phonologically native nonwords were learned best, whereas learning long nonwords leveled off after a few presentation cycles. Linear structural equation analyses showed an influence of three constructs—phonological sensitivity, vocabulary knowledge, and central attentional resources (M capacity)—on nonword learning, but the extent of their contributions depended on specific characteristics of the nonwords to be learned. Phonological sensitivity predicted learning of all nonword types except short native nonwords, vocabulary predicted learning of only short native nonwords, and M capacity predicted learning of short nonwords but not long nonwords. The discussion considers three learning processes—effortful activation of phonological representations, lexical mediation, and passive associative learning—that use different cognitive resources and could be involved in learning different nonword types.     

Stimulus class formation and concept learning: establishment of within- and between-set generalization and transitive relationships via conditional discrimination procedures

Three students with moderate mental retardation were taught a complex stimulus class with a two-choice conditional discrimination procedure applied across eight 10-member stimulus sets. Each set was composed of five age-appropriate and five age-inappropriate examples of clothing, accessories, and leisure items (e.g., a Walkman radio). Discrimination training was programmed serially across each set, and generalization probes were conducted concurrently among all sets. Generalization probes consisted of unreinforced conditional matching trials with comparison items being drawn from (a) the set undergoing training (within-set probes), (b) sets not undergoing training (between-set probes), and (c) both sample and comparison items from different sets (transitive stimulus control probes). Results indicate that within-set generalization, between-set generalization, and transitive stimulus relations controlled responding by all 3 students for items that had been contingently associated with reinforcement. However, items that gained control of responding through within-set and between-set generalization alone (i.e., not acquired through contingent reinforcement) remained at baseline levels during transitive stimulus control probes. Results are discussed in terms of a taxonomy of multiple sources of stimulus control that underlie socially defined and maintained stimulus classes.     

The two-alternative observing response procedure in rats: Preference for nondiscriminative stimuli and the effect of delay

A two-alternative choice procedure was used with rats to examine preference for discriminative stimuli (correlated with the occurrence of reinforcement) versus uncorrelated cues. Choice of discriminative stimuli was below chance, despite the use of very low levels of reinforcement (12.5% for some rats) known to produce a preference for discriminative cues. Levers that had been retracted during the stimulus presentation in Experiment 1 were extended in Experiment 2 to assess the role of response elicitation during the observed stimuli. In Experiment 3, the impact of cue-duration behaviors was further evaluated by lengthening the duration of the cues and providing an opportunity for an escape response. The preference for nondiscriminative stimuli was reversed only with increased exposure to the cues. The present results point to fundamental differences in the prevailing context of the choice procedure as compared to the usual free-operant observing design.     

Interaction of reinforcement conditions and developmental level in a two-choice discrimination task with children

A total of 540 first, fourth, and eighth graders, equally divided by sex, were run on a two-choice discrimination task under one of three reinforcement conditions: reward (R) for correct responses, punishment (P) for incorrect responses, or reward and punishment (RP) for correct and incorrect responses. Half the Ss were tested by a male E; half, by a female E. Across all developmental levels, learning was superior in the P group. Complex interactions involving sex of S and E underline the importance of organismic variables in discrimination learning and in specifying parameters of reinforcer effectiveness.     

Copying results and copying actions in the process of social learning: chimpanzees (Pan troglodytes) and human children (Homo sapiens)

There is currently much debate about the nature of social learning in chimpanzees. The main question is whether they can copy others' actions, as opposed to reproducing the environmental effects of these actions using their own preexisting behavioral strategies. In the current study, chimpanzees (Pan troglodytes) and human children (Homo sapiens) were shown different demonstrations of how to open a tube-in both cases by a conspecific. In different experimental conditions, demonstrations consisted of (1) action only (the actions necessary to open the tube without actually opening it); (2) end state only (the open tube, without showing any actions); (3) both of these components (in a full demonstration); or (4) neither of these components (in a baseline condition). In the first three conditions subjects saw one of two different ways that the tube could open (break in middle; caps off ends). Subjects' behavior in each condition was assessed for how often they opened the tube, how often they opened it in the same location as the demonstrator, and how often they copied the demonstrator's actions or style of opening the tube. Whereas chimpanzees reproduced mainly the environmental results of the demonstrations (emulation), human children often reproduced the demonstrator's actions (imitation). Because the procedure used was similar in many ways to the procedure that Meltzoff (Dev Psych 31:1, 1995) used to study the understanding of others' unfulfilled intentions, the implications of these findings with regard to chimpanzees' understanding of others' intentions are also discussed.     

Hebb learning, verbal short-term memory, and the acquisition of phonological forms in children

Recent work using the Hebb effect as a marker for implicit long-term acquisition of serial order has demonstrated a functional equivalence across verbal and visuospatial short-term memory. The current study extends this observation to a sample of five- to six-year-olds using verbal and spatial immediate serial recall and also correlates the magnitude of Hebb learning with explicit measures of word and nonword paired-associate learning. Comparable Hebb effects were observed in both domains, but only nonword learning was significantly related to the magnitude of Hebb learning. Nonword learning was also independently related to individuals' general level of verbal serial recall. This suggests that vocabulary acquisition depends on both a domain-specific short-term memory system and a domain-general process of learning through repetition.     

Generalization gradients in human predictive learning: Effects of discrimination training and within-subjects testing

Generalization gradients have been investigated widely in animal conditioning experiments, but much less so in human predictive learning tasks. Here, we apply the experimental design of a recent study on conditioned fear generalization in humans (Lissek et al., 2008) to a predictive learning task, and examine the effects of a number of relevant procedural parameters drawn from the generalization literature in animal conditioning. Experiment 1 shows that prior discrimination learning and steady-state testing procedures sharpen the gradient; Experiment 2 shows that within-subjects testing of the range of generalization stimuli also sharpens the gradient. In addition, Experiment 2 shows that, in case of very flat initial generalization, an orderly gradient can reveal itself through differential rates of extinction learning. Finally, Experiment 2 also evidenced an orderly gradient of generalization-of-extinction. These results suggest that discrimination processes have an important effect on the generalization of predictive learning in humans, and highlight behavioral analogies between animal conditioning and human predictive learning.     

Relationship between response rate and reinforcement frequency in variable-interval schedules: the effect of the concentration of sucrose reinforcement

Four rats were exposed to variable-interval schedules specifying a range of different reinforcement frequencies, using sucrose of two different concentrations and distilled water as the reinforcer. With sucrose, the rates of responding of all four rats were increasing negatively accelerated functions of reinforcement frequency, the data conforming closely to Herrnstein's equation; this was also true of the data from three of the four rats when distilled water was used as the reinforcer. The values of both constants in Herrnstein's equation were related to the sucrose concentration: the asymptotic response rate decreased, and the reinforcement frequency corresponding to the half-maximal response rate increased, with decreasing sucrose concentration.     

The impact of supervisory mentoring on personal learning and career outcomes: The dual moderating effect of self-efficacy

Using survey data from 226 employees and their supervisors in four manufacturing companies in China, we found that employee self-efficacy has a dual moderating effect on the impact of supervisory mentoring on subordinate career outcomes. Path analytic tests of mediated moderation suggested that self-efficacy moderates the mediated effects of supervisory mentoring on job performance and career satisfaction through personal learning such that the mediated effect on job performance is stronger when employees have higher self-efficacy, but the mediated effect on career satisfaction is stronger when they have lower self-efficacy.     

Controlled and automatic uses of memory in depressed patients: effect of retention interval lengths

The present study examines controlled and automatic uses of memory in clinically depressed patients by applying the Process Dissociation Procedure developed by Jacoby (1991) to a stem completion memory task with short and long retention intervals. The results show that the contribution of controlled processes is lower in depressed patients than in controls, especially for the longest retention interval, whereas the contribution of automatic processes is equivalent in both groups and unaffected by the length of the retention interval. These findings are discussed in a cognitive control framework.     

Color preference in pigeons: stimulus intensity and reinforcement contingency effects in the avoidance of blue stimuli.

In a procedure intended to determine color preference in pigeons (which partially replicated Catania, Owens, & von Lossberg, 1983), two keys were illuminated by different colors drawn from a set of amber, red, green, or blue stimuli; this was followed by the presentation of grain when either of the two colors was pecked. The grain was illuminated alternately across trials with the colors presented on the keys. In Experiment 1 the intensity of the color stimuli used was not equalized, whereas in Experiment 2 the intensity of the colors was equalized. The low preference for blue found in Experiment 1, as measured by differential key pecking, was not found in Experiment 2. The discriminability of the intensity-equalized colors was confirmed in Experiment 2a, in which equal-intensity color discrimination problems were presented. In Experiment 3, as in Catania et al. (1983), a response-independent reinforcement schedule was used, but with intensity-equalized colors. In contrast to Experiment 2, very low preference for blue was found here and in Experiment 4, which used a within-subject procedure. These findings suggest that pigeon color preference may be a function of intensity, but all controlling variables have not as yet been identified.     

Using emotional cues in a discrimination learning task: Effects of trait emotional intelligence and affective state

Individuals may differ in their ability to learn the significance of emotional cues within a specific context. If so, trait emotional intelligence (EI) may be associated with faster cue learning. This study (N = 180) tested whether trait EI predicts faster learning of a critical cue for discriminating “terrorists” from “non-terrorists”, using virtual-reality heads as stimuli. The critical cue was either facial emotion (positive or negative), or a neutral feature (hat size). Cognitive ability and subjective state were also assessed. Participants were faster to learn with an emotive cue. Surprisingly, high trait EI was correlated with poorer performance, especially early in learning. Subjective distress was also associated with impaired learning to emotive cues.     

Cue integration with categories: Weighting acoustic cues in speech using unsupervised learning and distributional statistics

During speech perception, listeners make judgments about the phonological category of sounds by taking advantage of multiple acoustic cues for each phonological contrast. Perceptual experiments have shown that listeners weight these cues differently. How do listeners weight and combine acoustic cues to arrive at an overall estimate of the category for a speech sound? Here, we present several simulations using a mixture of Gaussians models that learn cue weights and combine cues on the basis of their distributional statistics. We show that a cue‐weighting metric in which cues receive weight as a function of their reliability at distinguishing phonological categories provides a good fit to the perceptual data obtained from human listeners, but only when these weights emerge through the dynamics of learning. These results suggest that cue weights can be readily extracted from the speech signal through unsupervised learning processes.     

Self-control in mentally retarded adolescents: choice as a function of amount and delay of reinforcement.

Three severely mentally retarded adolescents were studied under discrete-trial procedures in which a choice was arranged between edible reinforcers that differed in magnitude and, in some conditions, delay. In the absence of delays the larger reinforcer was consistently chosen. Under conditions in which the smaller reinforcer was not delayed, increasing the delay to delivery of the larger reinforcer decreased the percentage of trials in which that reinforcer was chosen. All subjects directed the majority of choice responses to the smaller reinforcer when the larger reinforcer was sufficiently delayed, although the value at which this occurred differed across subjects. Under conditions in which the larger reinforcer initially was sufficiently delayed to result in preference for the smaller one, progressively increasing in 5-s increments the delay to both reinforcers increased percentage of trials with the larger reinforcer chosen. At sufficiently long delays, 2 of the subjects consistently chose the larger, but more delayed, reinforcer, and the 3rd subject chose that reinforcer on half of the trials. These results are consistent with the findings of prior studies in which adult humans responded to terminate noise and pigeons responded to produce food.     

Severity of sleep problems in children with severe learning difficulties: Description and correlates

In this study we have examined the percentage occurrence of settling and waking problems and of sleeping in the parents' bed in a sample of children with sleep problems. We found that about two-thirds had settling problems, nearly nine-tenths had waking problems, and one-third slept regularly in their parents' bed. Parents of children with sleep problems were more likely to experience a range of family problems than were parents of children without problems, and they were more likely to report a range of symptoms of stress. Most children with settling problems took at least two hours to settle to sleep at night. This behaviour was mainly tolerated or accepted by the parents. Parents gave a variety of suggestions as to triggers for settling problems, from being upset during the day to fears, illness and alterations in routine. Most parents thought the underlying explanation was the child's intellectual impairment. Over half the children with waking problems woke up every night, while 85% woke up at least three nights a week. One-third woke up three or more times a night. About two-thirds took up to half an hour to resettle, with one-third taking up to an hour. Parents (mainly mothers) tended to get up to attend to the waking child. About half of the children were thought to need attention because of physical disabilities. Illness, alteration in routine, becoming ‘overtired’ and ‘upset’ were thought to trigger waking problems. Intellectual impairment was again seen as the more general underlying reason for waking problems. Very few children were receiving treatment for their problems—7% were receiving medication and one was receiving a behavioural programme. Few parents had a systematic bedtime routine for their child and few had a consistent agreed response to settling or waking problems. When we examined the relationship between certain family variables and severity of sleep problems a number of relationships were found. Sleep problem severity was related to maternal responsiveness, maternal stress, impact of the child on the family, maternal behaviour towards the child, maternal attitudes towards the child and marital satisfaction. Severity of sleep problems was also related to certain child characteristics. Children with more severe problems tended to present more problems in their daytime behaviour. Sleep problem severity was also found to be related to child communication skills. These findings, together with those from other pilot studies, suggest that using behavioural methods of managing sleep problems might prove a promising way forward.     

Observation and discrimination learning in the rat: Effects of stimulus substitution

Effects of prior observation of modeling performances upon learning simultaneous visual discriminations were studied in nine groups of rats. Stimulus patterns which had been positive (“Cued”) or negative (“Uncued”) for the model animal and novel stimuli were presented. Observers learned faster if discriminations required approach to, rather than avoidance of, the previously positive stimulus. Approach to the negative stimulus was acquired more rapidly only if the second stimulus was novel. Approaches to a substituted new stimulus combined with either of the previously viewed stimulus patterns required nearly twice the training needed for a similar response attachment when both stimuli were novel. Attentional changes appear to underlie the stimulus control exerted over the observer rat in instrumental learning situations.     

Same/different concept learning in the pigeon: the effect of negative instances and prior adaptation to transfer stimuli

Pigeons were trained on a matching-to-sample or oddity-from-sample task with shapes (circle and plus). Half of each group was exposed to “negative instance” trials i.e., for matching birds, neither comparison key matched the sample, and for oddity birds both comparison keys matched the sample. When all birds were transferred to a new task involving colors (red and green), nonshifted birds (transferred from matching to matching, or oddity to oddity) performed significantly better than shifted birds (transferred from matching to oddity, or oddity to matching), but only if they had experienced negative instances of the training concept. When all birds were exposed to negative instances of the transfer task and then transferred to a new color task (yellow and blue), dramatic transfer effects were observed. The effect of pre-exposure to the yellow and blue colors, in order to reduce transfer-stimulus novelty, had a minor effect on transfer.     

Orthographic learning via self-teaching in children learning to read English: effects of exposure, durability, and context

This experiment investigated orthographic learning via self-teaching in 8- and 9-year-olds learning to read English. Children were exposed to novel words, and following a 1- or 7-day delay interval, orthographic learning was assessed by asking children to select previously seen novel words from an array of visually and phonologically similar foils. Novel words were exposed either in meaningful text or in isolation, and number of exposures was manipulated with each novel word appearing once, twice, or four times. Learning increased as a function of number of exposures, although some evidence of durable one-trial learning was observed. Context played no role, suggesting that orthographic learning is not dependent on meaning-based information. In general, these findings offer support for the central aspects of Share's self-teaching hypothesis. However, although we observed a general relation between phonological decoding and orthographic learning, the relation did not hold at an item-by-item level of analysis, suggesting that a strong version of Share's item-based account is not correct.