THE EFFECTS OF KNOWN-ITEM INTERSPERSAL ON ACQUISITION AND RETENTION OF SPELLING AND SIGHTREADING WORDS1

The use of well-documented procedures such as shaping, differential reinforcement, and fading may not be the most practical for teaching certain academic behaviors. An alternative procedure of interspersing trials on previously trained items with trials on unknown items has been suggested, but its effects on acquisition and retention have not been systematically examined. This study investigated the effects of interspersing known items during training on new tasks. Six mentally retarded adolescents were given pretests on spelling and sightreading words, which were divided into pools of learned and unlearned items. Training and baseline conditions were implemented concurrently, using a multi-element design. During interspersal training sessions, 10 known words from the pretest were alternately presented with each of 10 test words that were incorrect on the pretest. The ratio of previously mastered words to test words was gradually reduced. During baseline sessions, 10 different test words were presented without alternation of previously known words. During this condition, a procedure involving high-density social reinforcement contingent on task-related behaviors, but not necessarily correct responses, was later introduced, followed by a return to the original noninterspersal baseline. During all conditions, test words were deleted and replaced after meeting a mastery criterion of three consecutive correct trials. Retention tests were administered over learned test words for all conditions, at specified intervals. Results showed that both acquisition and retention of spelling and sightreading words were facilitated by the interspersal procedure. All subjects acquired more words during the interspersal condition than either the high-density or baseline conditions. The effectiveness of the procedure may possibly be attributed to better maintenance of attending behavior to unknown items as a function of the inclusion of known items, which directly increase the amount of reinforcement for correct responses during the early stages of skill acquisition.     

The differential outcomes procedure can overcome self-bias in perceptual matching

There are biases in perceptual matching between shapes and labels referring to familiar others, compared with when the labels refer to unfamiliar people. We assessed whether these biases could be affected by differential feedback (using the differential outcomes procedure [DOP]) compared with when feedback is provided using a nondifferential outcomes procedure (NOP). Participants formed associations between simple geometric shapes and labels referring to people the participant did or did not know (self, best friend, other). Subsequently, the task was to match a label to one of two shapes shown on a trial. When feedback for correct responses was given following the NOP condition, matches were faster to known people (self and friend) compared with those to an unknown person (stranger). However, this advantage for known personal relations was eliminated when participants were given feedback for correct responses following the DOP condition. The data are consistent with prior work showing that the DOP can facilitate the learning of taxing associations (for the stranger stimuli relative to the familiar self and friend stimuli). In addition, the results suggest that the facilitated perceptual matching for stimuli associated to individuals known personally may reflect better individuation of the association between the shape stimulus and the label, a process enhanced by using a DOP for associations with unfamiliar people.     

Conflict in object affordance revealed by grip force

Viewing objects can result in automatic, partial activation of motor plans associated with them-"object affordance". Here, we recorded grip force simultaneously from both hands in an object affordance task to investigate the effects of conflict between coactivated responses. Participants classified pictures of objects by squeezing force transducers with their left or right hand. Responses were faster on trials where the object afforded an action with the same hand that was required to make the response (congruent trials) compared to the opposite hand (incongruent trials). In addition, conflict between coactivated responses was reduced if it was experienced on the preceding trial, just like Gratton adaptation effects reported in "conflict" tasks (e.g., Eriksen flanker). This finding suggests that object affordance demonstrates conflict effects similar to those shown in other stimulus-response mapping tasks and thus could be integrated into the wider conceptual framework on overlearnt stimulus-response associations. Corrected erroneous responses occurred more frequently when there was conflict between the afforded response and the response required by the task, providing direct evidence that viewing an object activates motor plans appropriate for interacting with that object. Recording continuous grip force, as here, provides a sensitive way to measure coactivated responses in affordance tasks.     

Conflict in object affordance revealed by grip force

Viewing objects can result in automatic, partial activation of motor plans associated with them—“object affordance”. Here, we recorded grip force simultaneously from both hands in an object affordance task to investigate the effects of conflict between coactivated responses. Participants classified pictures of objects by squeezing force transducers with their left or right hand. Responses were faster on trials where the object afforded an action with the same hand that was required to make the response (congruent trials) compared to the opposite hand (incongruent trials). In addition, conflict between coactivated responses was reduced if it was experienced on the preceding trial, just like Gratton adaptation effects reported in “conflict” tasks (e.g., Eriksen flanker). This finding suggests that object affordance demonstrates conflict effects similar to those shown in other stimulus–response mapping tasks and thus could be integrated into the wider conceptual framework on overlearnt stimulus–response associations. Corrected erroneous responses occurred more frequently when there was conflict between the afforded response and the response required by the task, providing direct evidence that viewing an object activates motor plans appropriate for interacting with that object. Recording continuous grip force, as here, provides a sensitive way to measure coactivated responses in affordance tasks.     

Rapid fast-mapping abilities in 2-year-olds

Learning a new word consists of two primary tasks that have often been conflated into a single process: referent selection, in which a child must determine the correct referent of a novel label, and referent retention, which is the ability to store this newly formed label-object mapping in memory for later use. In addition, children must be capable of performing these tasks rapidly and repeatedly as they are frequently exposed to novel words during the course of natural conversation. Here we used a preferential pointing task to investigate 2-year-olds’ (N = 72) ability to infer the referent of a novel noun from a single ambiguous exposure and their ability to retain this mapping over time. Children were asked to identify the referent of a novel label on six critical trials distributed throughout the course of a 10-min study involving many familiar and novel objects. On these critical trials, images of a known object and a novel object (e.g., a ball and a nameless artifact constructed in the laboratory) appeared on two computer screens and a voice asked children to “point at the _____ [e.g., glark].” Following label onset, children were allowed only 3 s during which to infer the correct referent, point at it, and potentially store this new word-object mapping. In a final posttest trial, all previously labeled novel objects appeared and children were asked to point to one of them (e.g., “Can you find the glark?”). To succeed, children needed to have initially mapped the novel labels correctly and retained these mappings over the course of the study. Despite the difficult demands of the current task, children successfully identified the target object on the retention trial. We conclude that 2-year-olds are able to fast map novel nouns during a brief single exposure under ambiguous labeling conditions.     

THE RELATION BETWEEN CHOOSING AND WORKING PREVOCATIONAL TASKS IN TWO SEVERELY RETARDED YOUNG ADULTS

This study investigated the relation between prevocational preference, as measured by the client's selection of a task object, and the work that followed that choice. After selecting a task object, the clients worked a task previously assessed to be more or less preferred than the one indicated by the object. The results indicated that when the selection represented a task that was less preferred than the one actually worked, choices for that object increased on subsequent trials. Conversely, when the selection represented a task that was more preferred than the task subject actually worked, choices for the object decreased on subsequent trials. The work that followed object choices reinforced or punished subsequent selections. These findings indicated that the clients' object choices were valid indicators of their preference for working different tasks. They were also consistent with Premack's principle that one class of responses may reinforce or punish a different class of responses for the same individual.     

The reciprocal relation between sleep and memory in infancy: Memory‐dependent adjustment of sleep spindles and spindle‐dependent improvement of memories

Sleep spindle activity in infants supports their formation of generalized memories during sleep, indicating that specific sleep processes affect the consolidation of memories early in life. Characteristics of sleep spindles depend on the infant's developmental state and are known to be associated with trait‐like factors such as intelligence. It is, however, largely unknown which state‐like factors affect sleep spindles in infancy. By varying infants’ wake experience in a within‐subject design, here we provide evidence for a learning‐ and memory‐dependent modulation of infant spindle activity. In a lexical‐semantic learning session before a nap, 14‐ to 16‐month‐old infants were exposed to unknown words as labels for exemplars of unknown object categories. In a memory test on the next day, generalization to novel category exemplars was tested. In a nonlearning control session preceding a nap on another day, the same infants heard known words as labels for exemplars of already known categories. Central–parietal fast sleep spindles increased after the encoding of unknown object–word pairings compared to known pairings, evidencing that an infant's spindle activity varies depending on its prior knowledge for newly encoded information. Correlations suggest that enhanced spindle activity was particularly triggered, when similar unknown pairings were not generalized immediately during encoding. The spindle increase triggered by previously not generalized object–word pairings, moreover, boosted the formation of generalized memories for these pairings. Overall, the results provide first evidence for a fine‐tuned regulation of infant sleep quality according to current consolidation requirements, which improves the infant long‐term memory for new experiences.     

Monitoring the Changing Status of Semantic Memory in Alzheimer's Disease: An Evaluation of Several Process Measures

The deficits in generating correct words on verbal fluency tasks exhibited by patients with Alzheimer's disease (AD) are accompanied by fewer switching responses, smaller phonemic and semantic cluster sizes, and greater than normal percentages of errors and category labels. On category fluency tasks, patients generate a greater proportion of words that are prototypical of their semantic class. To determine whether any of these supplementary measures of verbal fluency performance might be useful in revealing processes involved in the decline of semantic memory in AD, we studied 219 patients with AD and 115 elderly control participants longitudinally. Previously reported group differences between patients and controls were replicated, but changes in average cluster size, error rates, and prototypicality were not related to changes in overall severity of dementia and test-retest stability was only modest. The change in the percentage of labels generated on the Supermarket task was related to changes in dementia severity, but test-retest stability on this measure was quite low. All of these process measures appear to reflect only the current status of the patient's attention to the task and access to semantic knowledge, but they do not forecast future performance. The numbers of switching responses on the fluency tasks were sensitive to differences between clinically deteriorated and clinically stable patients and showed fairly high test-retest stability. However, the number of switching responses is so highly correlated with the number of correct words that it contributes little to the understanding of the processes involved in the progressive decline in performance on fluency tasks by patients with AD.     

THE LIMITS AND MOTIVATING POTENTIAL OF SENSORY STIMULI AS REINFORCERS FOR AUTISTIC CHILDREN

This study investigated the reinforcing properties, limits, and motivating potentials of sensory stimuli with autistic children. In the first phase of the study, four intellectually retarded autistic children were exposed to three different types of sensory stimulation (vibration, music, and strobe light) as well as edible and social reinforcers for ten-second intervals contingent upon six simple bar pressing responses. In the second phase, the same events were used as reinforcers for correct responses in learning object labels. The results indicated that: (a) sensory stimuli can be used effectively as reinforcers to maintain high, durable rates of responding in a simple pressing task; (b) ranked preferences for sensory stimuli revealed a unique configuration of responding for each child; and (c) sensory stimuli have motivating potentials comparable to those of the traditional food and social reinforcers even when training receptive language tasks.     

TRANSFER BETWEEN RECEPTIVE AND PRODUCTIVE LANGUAGE IN DEVELOPMENT ALLY DISABLED CHILDREN

The purpose of this study was to examine the relationship between receptive and productive language acquisition in developmentally disabled children. A single-subject operant methodology was employed to evaluate the effect of training in one mode on performance in the other mode. Noun labels for pictured objects were used as the unit of analysis. Six children with severe language deficits participated in the experiment. Each subject learning to identify a different set of five pictures in each of four successively administered training conditions. In the first condition, a set of pictures was trained in the productive mode. In the second condition, a different set was trained in the receptive mode. These training conditions were then repeated using two additional sets of pictures. Training was done using reinforcement for correct responses and prompting for incorrect responses. Nonreinforced probes were conducted throughout training to assess performance in the untrained mode. The pictures in each set were trained successively so that transfer across the language modes could be studied separately for each response trained. All subjects successfully met the criteria for learning each picture set in both the receptive and productive training conditions. The probe data showed that opposite-modality performance improved as a function of both types of training, although performance levels differed. After productive training, five of six subjects' performance was highly accurate on receptive probes. By contrast, receptive training resulted in limited correct productive performance. Transfer from receptive training was negatively related to subjects' use of extra-experimental labels on productive probe trials. In addition to these competing response errors, subjects frequently made articulation errors. The findings suggest that for retarded children similar to those studied here, productive training will be sufficient to establish accurate receptive performance on vocabulary tasks. However, receptive training does not appear to be either a necessary or a sufficient condition for productive performance. The results do not support the reception-then-production training sequence based on normal language development.     

The role of attention in motion extrapolation: are moving objects 'corrected' or flashed objects attentionally delayed?

Objects flashed in alignment with moving objects appear to lag behind [Nijhawan, 1994 Nature (London) 370 256-257]. Could this 'flash-lag' effect be due to attentional delays in bringing flashed items to perceptual awareness [Titchener, 1908/1973 Lectures on the Elementary Psychology of Feeling and Attention first published 1908 (New York: Macmillan); reprinted 1973 (New York: Arno Press)]? We overtly manipulated attentional allocation in three experiments to address the following questions: Is the flash-lag effect affected when attention is (a) focused on a single event in the presence of multiple events, (b) distributed over multiple events, and (c) diverted from the flashed object? To address the first two questions, five rings, moving along a circular path, were presented while observers attentively tracked one or multiple rings under four conditions: the ring in which the disk was flashed was (i) known or (ii) unknown (randomly selected from the set of five); location of the flashed disk was (i) known or (ii) unknown (randomly selected from ten locations). The third question was investigated by using two moving objects in a cost-benefit cueing paradigm. An arrow cued, with 70% or 80% validity, the position of the flashed object. Observers performed two tasks: (a) reacted as quickly as possible to flash onset; (b) reported the flash-lag effect. We obtained a significant and unaltered flash-lag effect under all the attentional conditions we employed. Furthermore, though reaction times were significantly shorter for validly cued flashes, the flash-lag effect remained uninfluenced by cue validity, indicating that quicker responses to validly cued locations may be due to the shortening of post-perceptual delays in motor responses rather than the perceptual facilitation. We conclude that the computations that give rise to the flash-lag effect are independent of attentional deployment.     

Tracking the displacement of objects: a series of tasks with great apes (Pan troglodytes, Pan paniscus, Gorilla gorilla, and Pongo pygmaeus) and young children (Homo sapiens)

The authors administered a series of object displacement tasks to 24 great apes and 24 30-month-old children (Homo sapiens). Objects were placed under 1 or 2 of 3 cups by visible or invisible displacements. The series included 6 tasks: delayed response, inhibition test, A not B, rotations, transpositions, and object permanence. Apes and children solved most tasks performing at comparable levels except in the transposition task, in which apes performed better than children. Ape species performed at comparable levels in all tasks except in single transpositions, in which chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) performed better than gorillas (Gorilla gorilla) and orangutans (Pongo pygmeaus). All species found nonadjacent trials and rotations especially difficult. The number of elements that changed locations, the type of displacement, and having to inhibit predominant reaching responses were factors that negatively affected the subjects' performance.     

Preschoolers’ understanding of multiple orientations to reality: The adjectives task

Preschoolers’ understanding that an object can be accurately described using two different non-synonymous words was investigated using a task in which children (N = 36) had to judge which of two animals had provided correct adjectival labels for a series of pictures. For some pictures, only one animal provided a correct adjective, for some both animals were correct, and for some neither was correct. For all types of judgement, 4-year-olds outperformed 3-year-olds. Children in both age groups performed worst on trials where both animals were correct. Children's performance on the adjectives task related to concurrent understanding of the appearance–reality distinction, but not to false-belief task performance. Implications for children's mentalizing development are discussed.     

The emergence of conditioned reinforcement from observation

We report an experiment in which observations of peers by six 3-5-year-old participants under specific conditions functioned to convert a small plastic disc or, for one participant, a small piece of string, from a nonreinforcer to a reinforcer. Prior to the observational procedure, we compared each participant's responding on (a) previously acquired performance tasks in which the child received either a preferred food item or the disc (string) for correct responses, and (b) the acquisition of new repertoires in which the disc (string) was the consequence for correct responses. Verbal corrections followed incorrect responses in the latter tasks. The results showed that discs and strings did not reinforce correct responses in the performance tasks, but the food items did; nor did the discs and strings reinforce correct responses in learning new repertoires. We then introduced the peer observation condition in which participants engaged in a different performance task in the presence of a peer who also performed the task. A partition blocked the participants from seeing the peers' performance. However, participants could observe peers receiving discs or strings. Participants did not receive discs or strings regardless of their performance. Peer observation continued until the participants either requested discs or strings repeatedly, or attempted to take discs or strings from the peers. Following the peer observation condition, the same performance and acquisition tasks in which participants had engaged prior to observation were repeated. The results showed that the discs and strings now reinforced correct responding for both performance and acquisition for all participants. We discuss the results with reference to research involving nonhuman subjects that demonstrated the observational conditioning of reinforcers.     

Effects of criterion-level probing on demonstrating newly acquired discriminative behavior.

The purpose of the study was to determine whether probes of the final criterion-level discrimination administered during and after training provided an accurate measure of acquisition. Training and probe stimuli were designed to make training and probe trials initially very discriminable and then progressively less discriminable as training progressed. Initially, the discrimination required on probe trials was more difficult than the discrimination required on training trials. However, this difference in difficulty was gradually eliminated as training stimuli were topographically altered and made identical to probe stimuli by the end of training. Results showed that while correct responding was maintained throughout training, error patterns occurred on all probe trials administered during training. Error patterns developed regardless of whether probe trials occurred only at the beginning of training sessions (temporally discriminable probes) or were randomly interspersed in the training sessions (temporally indiscriminable probes). Probe error patterns seemed to be controlled by the stimulus properties of training and probe trials. Thus, probes did not measure acquisition as it occurred during training. Probe error patterns were maintained when probes were administered after completion of training. This final measure of acquisition did not agree with the demonstration of acquisition provided by the final training trial. The results suggest that probe trials can measure a different stimulus-response relationship from that trained when training starts with an easier or known discrimination and probes involve a final or criterion test of a more difficult or unknown discrimination. Stimulus control of correct responses versus error patterns is discussed.     

Switching or sharing in dual-task line-length discrimination?

In two experiments, we tested whether subjects switched or shared attention between two simultaneously relevant line-length discrimination tasks. Switching models that allowed within- as well as between-trial switching were considered. In the first experiment, stimulus duration was varied randomly from trial to trial. With varied durations, many switching models predict negative contingencies: for a given duration and attentional allocation, accurate responses on one task should be associated with inaccurate responses on the other task. The results, however, showed no negative contingencies, which is consistent with sharing models. In the second experiment, stimulus duration was reduced to 20 msec, yet responses were more than 75% correct overall. This implies that information was obtained about both of the tasks within single trials, contradicting those switching models which predict that information can be obtained from, at most, one task within a period of 20 msec or less. In short, the results of both experiments support sharing models.     

Differcntial feature analysis in the recognition memory of reflective and impulsive children

Seventy-two children. 18 reflective, and 18 impulsive first and fifth graders were tested in a forced-choice recognition memory task. Experimental conditions systematically varied the possibility that correct responses could be made on the basis of verbal labels, visual feature analyses, or both. Although reflective children made more correct recognition choices than did impulsive children under all experimental conditions, this difference was, as predicted, significant only in a condition in which the sole basis for correct response depended on a purely visual feature analysis. Order of condition difficulty indicated that visual feature analysis independent of verbal processes was responsible for successful recognition performance in these Ss. Results were discussed with reference to the feature-testing model for recognition proposed by Selfridge and Neisser.     

Perceptual priming is not a necessary consequence of semantic classification of pictures

Four experiments investigated how repetition priming of object recognition is affected by the task performed in the prime and test phases. In Experiment 1 object recognition was tested using both vocal naming and two different semantic decision tasks (whether or not objects were manufactured, and whether or not they would be found inside the house). Some aspects of the data were inconsistent with contemporary models of object recognition. Specifically, object priming was eliminated with some combinations of prime and test tasks, and there was no evidence of perceptual (as opposed to conceptual or response) priming in either semantic classification task, even though perceptual identification of the objects is required for at least one of these tasks. Experiment 2 showed that even when perceptual demands were increased by brief presentation, the inside task showed no perceptual priming. Experiment 3 showed that the inside task did not appear to be based on conceptual priming either, as it was not primed significantly when the prime decisions were made to object labels. Experiment 4 showed that visual sensitivity could be restored to the inside task following practice on the task, supporting the suggestion that a critical factor is whether the semantic category is preformed or must be computed. The results show that the visual representational processes revealed by object priming depend crucially on the task chosen.     

Comprehension and production of body part labels in 2‐ to 3‐year‐old children

This study examined which body part labels children could (i) produce when the experimenter touched different locations on her own body, asking each time ‘What's this?’ and (ii) comprehend by touching the correct locations on their own bodies in response to the experimenter asking ‘Where's the [body‐part label]?’. Seventeen children aged between 26 and 41 months, tested in a repeated measures procedure, were presented with 50 different body part stimuli in 200 test trials per child. Overall, the children produced fewer body part labels than they could comprehend. The accuracy of children's responses depended on (i) the location or extent of each body part (facial and broad body features were better known; joints and features in or attached to broad body parts the least well known); (ii) the amount of sensory (but not motor) representation each body part has in the human cortex; and (iii) whether a body part was commonly named by caregivers. These results present a precise mapping of the body parts that young children are able to name and locate on their own bodies in response to body part names; they suggest several possible determinants of lexical‐semantic body knowledge and add to the understanding of how it develops in childhood.     

Effect of varying picture-sentence congruence on children's free recall.

70 fourth-grade children were shown objects arbitrarily arranged in an integrated scene. Subjects were randomly assigned to conditions which either presented a sentence that correctly labeled and correctly described the physical arrangement of the objects, presented a sentence containing the correct labels of the objects but not the correct physical arrangement, or presented a sentence which did not contain the correct labels and incorrectly described the physical arrangement. Control conditions either provided subjects with correct labels or omitted presentation of verbal prompts. Congruence between the object display and the sentence produced significantly higher recall and clustering than the incongruence or control conditions. The incongruence conditions did not produce significantly higher recall than the control conditions, suggesting that incongruence interferes with formation of stable grouping of items which appears to be an important factor in facilitating free recall.