Deferred imitation and declarative memory in domestic dogs

This study demonstrates for the first time deferred imitation of novel actions in dogs (Canis familiaris) with retention intervals of 1.5 min and memory of familiar actions with intervals ranging from 0.40 to 10 min. Eight dogs were trained using the ‘Do as I do’ method to match their own behaviour to actions displayed by a human demonstrator. They were then trained to wait for a short interval to elapse before they were allowed to show the previously demonstrated action. The dogs were then tested for memory of the demonstrated behaviour in various conditions, also with the so-called two-action procedure and in a control condition without demonstration. Dogs were typically able to reproduce familiar actions after intervals as long as 10 min, even if distracted by different activities during the retention interval and were able to match their behaviour to the demonstration of a novel action after a delay of 1 min. In the two-action procedure, dogs were typically able to imitate the novel demonstrated behaviour after retention intervals of 1.5 min. The ability to encode and recall an action after a delay implies that facilitative processes cannot exhaustively explain the observed behavioural similarity and that dogs’ imitative abilities are rather based on an enduring mental representation of the demonstration. Furthermore, the ability to imitate a novel action after a delay without previous practice suggests presence of declarative memory in dogs.     

USING TIME DELAY TO PROMOTE SPONTANEOUS SPEECH IN AN AUTISTIC CHILD

One of the frequently observed deficits in autistic children is their lack of spontaneous speech. We used a multiple baseline across behaviors to investigate the effectiveness of a time delay procedure for inducing spontaneous speech in a 10-year-old male autistic child during play. We first taught the child to imitate the experimenter's verbal prompts that described the child's motor response. Once the child reached criteria on imitation, we implemented baseline wherein an immediate verbal prompt for speech was provided after each of the child's motor responses. Intervention consisted of a gradual delay in the presentation of the verbal prompts. The time delay effectively increased the child's spontaneous speech on trained items; some generalization to untrained items also occurred, but only within the same behavioral class of car play. Generalization was also observed across settings. Spontaneous speech remained at high levels during the 4-month maintenance for the behavior of car play but decreased for a second behavior. Decreases in the child's response latencies suggest that spontaneous speech may be an anticipatory verbal response.     

Memory by association: Integrating memories prolongs retention by two-year-olds

Recalling one memory often leads to the recollection of other memories that share overlapping features. This phenomenon, spreading activation, was originally documented in studies conducted with verbal adults, and more recently, it has been demonstrated with preverbal infants. Here, we examine the effect of spreading activation on long-term retention by 2-year-olds. Participants were tested in the Visual Recognition Memory (VRM) paradigm and the deferred imitation paradigm. Typically, infants of this age exhibit retention in the VRM paradigm for 24 h, while they exhibit retention in the deferred imitation paradigm for at least 8 weeks. In the present experiment, we paired these tasks together during original encoding and tested infants after an 8-week delay. Two-year-olds exhibited retention in both tasks. That is, when these two tasks initially occurred together – one task that is extremely memorable and one that is not – retrieving the memory of the more memorable task cued retrieval of the less memorable task, extending its longevity.     

Where did you park your car? Analysis of a naturalistic long-term recency effect

Abstract

Three experiments studied the long-term retention of parking locations. In Experiment 1, members of the Applied Psychology Unit (MU) attempted to recall where they had parked during the morning and afternoon of each of the previous 12 working days. A marked recency effect was observed. In Experiment 2, members of the APU Subject Panel were invited for a single test session, and asked where they had parked after a delay of 2 hours, 1 week or 1 month. Recall was excellent and did not differ as a function of delay, allowing a simple trace decay interpretation to be ruled out. A third experiment invited subjects to attend on two occasions separated by a 2-week interval. The subjects were then required to recall their parking locations some 4 weeks after either their first visit or their second visit. Performance in both groups was inferior to that observed in Experiment 2, and declined over time. A temporal discrimination model, based on laboratory studies of both long-term and short-term recency in free recall, offers a plausible explanation of our results.     

Implicit long-term memory for duration in young children

The aim of the present study was to investigate young children's ability to maintain in long-term memory a duration of an action they have previously experienced (i.e., implicit long-term memory for duration). Children aged 3 and 5 years were trained to produce an action for 5 s by simultaneous imitation of the experimenter's action. Then, they were tested after a retention interval lasting for 1, 24, or 48 hours (Experiment 1), or 6 days, 6 weeks, or 6 months (Experiment 2). The results showed that the young children remembered the learned duration after 48 hours and 6 months at the age of 3 and 5 years, respectively, although the temporal performance decreased at the 1 hour and the 6 weeks retention intervals for the first and the second age group. These findings are discussed in the framework of a discrepancy in the memory retention of duration as a function of the nature of the memory system, i.e., implicit or explicit.     

The consequences of failing to imitate

Infants were shown three modeled acts presented in sequence. Imitation of one, two, or three of the modeled acts or failure to imitate was then observed. Distress was assessed prior to and following modeling. Infants who failed to imitate at least one act displayed a high level of distress. As a control, the same infants on another day observed the random manipulation of the stimuli. Distress failed to occur when the infants failed to imitate the scattering procedure. These results are discussed in terms of the child's development of internal standards. That is, during the latter part of the second year of life, infants show considerable distress when they fail to imitate coherent modeled acts. Since distress did not occur when the model simply scattered the stimuli, we assumed that interruption of play was not an incentive for distress. Deferred imitation was noted for older but not the younger cohorts.     

Observing response acquisition: preference for unpredictable appetitive rewards obtained under conditions predicted by DMOD

In five E-maze experiments, rats were given a choice between receiving reward and nonreward in a situation where stimuli were correlated with reward outcome (predictable situation) versus one where the stimuli were uncorrelated with reward outcome (unpredictable situation). Preference for the unpredictable situation occurred under the following conditions: (a) small (one 37-mg pellet), immediate rewards; (b) small, delayed (15 s) rewards, if the cues correlated with reward outcome were absent during the delay interval; (c) large (15 pellets), immediate rewards if a difficult discrimination was required; and (d) if the stimulus predicting nonreward was present at the choice point. Preference for the predictable situation was strongest if reinforcement was delayed and large or the stimulus predicting reward was present at the choice point. A weaker preference for the predictable situation occurred if reinforcement was immediate and large and a simple discrimination was required or if reinforcement was large and delayed and the cues that correlated with reward outcome were absent during the delay interval. The results support the predictions of DMOD (Daly modification of the Rescorla-Wagner model), a mathematical model of appetitive learning (Daly & Daly, 1982).     

Spontaneous imitation in the social interactions of young people with developmental delay and their adult carers

This paper examines the presence of spontaneous imitation within the social interactions of young people with developmental delay and their adult carers. There have been only a handful of observational studies examining imitation in this population, despite the relevance of such work to contemporary theoretical debates about imitation and the potential that imitation holds as an intervention for promoting communicative skills. The play of eight young people and 13 adult carers over 10 sessions at an after‐school club was videotaped and analysed for the presence and impact of spontaneous imitative bouts. Results showed that, in the majority of cases, it was adults who initiated imitative bouts and that the young people generally did not reciprocate such acts. However, even such brief instances of adult imitation were sufficient to increase the children's subsequent smiles and speech vocalizations, as well as the adults' own use of smiling, eye contact, and speech vocalizations. These findings confirm that these young people are sensitive to imitation. The implications for designing interventions that promote communicative exchanges in young people with developmental delay are discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

The role of a positive model,a frustrating situation and aggressive context on imitation

Thirty-two groups of four naive Ss and one accomplice participated in this 2 × 2 × 2 experiment designed to test conditions facilitating imitation of a competent model played by the accomplice. It was assumed that the psychological distance between the competent model and the Ss would be lessened so that imitation would increase: 1. if the model was friendly rather than hostile, 2. if the situation was non-frustrating rather than frustrating, and 3. if aggression was permitted rather than forbidden. Imitation was measured by the Ss' reproduction of the model's two mannerisms, and was found to be significantly influenced in the predicted way by the three variables. However, the freedom to aggress did not lessen psychological distance. Alternative explanations are provided for these results.     

Mother versus stranger: a triadic situation of imitation at the end of the first year of life

This study presents two experiments investigating 8‐ and 12‐month‐old infants' imitative behaviour. Seventy‐two 8‐month‐olds and seventy‐two 12‐month‐olds were observed in a triadic situation which included their mother and a stranger. Depending on the condition, either the mother or the stranger acted as the demonstrator and either stayed close or withdrew after the demonstration, during the response period. In addition to imitative acts, visual exploration and smiles addressed, respectively, to each partner were computed. Results showed that at both ages, neither the familiarity nor the position of the partner has an effect on the number of target gestures that are imitated. At 12 months, infants looked and smiled more at the stranger when he demonstrated target actions but no difference was found when the mother acted as demonstrator. Moreover, 12‐month‐old infants looked more at the demonstrating partner immediately after their first imitation. At 8 months, infants paid more attention to the stranger in all conditions except when the mother performed the target actions and moved away, a pattern that suggests a referencing to the mother. Results from the gaze and smile variables suggest that with age different motivations (social contact, exploration of objects) induce imitation. Copyright © 2003 John Wiley & Sons, Ltd.     

Recovery of susceptibility following audiogenic seizure in mice.

The rate at which SJL/J mice recover susceptibility following an initial sound-induced seizure was examined. Fewer than 15% of the subjects seized when retested after a 2-min delay, and only 50% reseized after a 10-min delay. The likelihood of a second seizure was enhanced if the initial seizure exhibited a rapid progression to clonus. During the retest, seizures progressed more slowly than during the initial test, which indicates that recovery was not complete even if a second seizure was induced. Finally, recovery of seizure susceptibility was prevented as long as the subject continued to be exposed to intense auditory stimulation following the initial convulsion, an effect previously noted by Alexander and Kopeloff (1980). The findings are discussed in terms of a recently proposed central inhibitory model of the recovery of audiogenic seizure susceptibility.     

Reciprocal Imitation Following Adult Imitation by Children with Autism

This study examined the effects of adult imitation and adult playfulness on the imitation, social attention and initiation of new behaviours by non‐verbal preschoolers with autism. Videotapes taken from a previous study were recoded for the adult's imitation and playful behaviour and the children's imitation, social attention (looking at the adult's actions) and initiation of new behaviours. In the original study, twenty non‐verbal, 4‐ to 6‐year‐old children with autism were randomly assigned to an imitation or a contingent responsivity group. Both groups of children engaged in an intervention phase (during which the adult imitated the children or contingently responded to them) and a subsequent spontaneous play phase (during which the adult interacted spontaneously with the children). ANOVA for the current study revealed that the imitation group children versus the contingent responsivity group children spent a greater percent time showing social attention and initiating new behaviours during the intervention phase and showing social attention and imitating the adult's behaviours during the subsequent spontaneous play phase. A correlation analysis yielded significant correlations between the percent time the adult imitated the child during the intervention phase and the percent time the child showed social attention during the same intervention phase and imitating the adult during the subsequent spontaneous play phase. Adult imitation and playfulness during the spontaneous play phase were also correlated with the children's social attention during that phase. Copyright © 2013 John Wiley & Sons, Ltd.     

Long-term memory,forgetting, and deferred imitation in 12-month-old infants

Long-term recall memory, as indexed by deferred imitation, was assessed in 12-month-old infants. Independent groups of infants were tested after retention intervals of 3 min, 1 week and 4 weeks. Deferred imitation was assessed using the ‘observation-only’ procedure in which infants were not allowed motor practice on the tasks before the delay was imposed. Thus, the memory could not have been based on re-accessing a motor habit, because none was formed in the first place. After the delay, memory was assessed either in the same or a different environmental context from the one in which the adult had originally demonstrated the acts. In Experiments 1 and 3, infants observed the target acts while in an unusual environment (an orange and white polka-dot tent), and recall memory was tested in an ordinary room. In Experiment 2, infants observed the target acts in their homes and were tested for memory in a university room. The results showed recall memory after all retention intervals, including the 4 week delay, with no effect of context change. Interestingly, the forgetting function showed that the bulk of the forgetting occurred during the first week. The findings of recall memory without motor practice support the view that infants as young as 12 months old use a declarative (nonprocedural) memory system to span delay intervals as long as 4 weeks.     

Reexposure breeds recall: effects of experience on 9-month-olds' ordered recall

On the basis of three experiences, 9-month-olds recall specific events after one month. We tested whether multiple experiences are necessary, or merely facilitative, of 9-month-olds' long-term recall. In two experiments, using deferred imitation, infants were exposed to multi-step sequences either one time, two times, or three times prior to a one-month delay. In Experiment 1, regardless of the number of experiences, infants did not demonstrate recall. In Experiment 2, infants were tested on and reexposed to the events after one week; recall was tested again one month later. Performance after 1 week in Experiment 2 was greater than performance after one month in Experiment 1. Moreover, presumably as a function of reexposure after one week, infants recalled the individual actions of the events one month later. Infants in the three-experience condition also evidenced ordered recall after one month. Implications for the developmental status of the neural substrate supporting long-term recall are discussed.     

Exploring memory in infancy: deferred imitation and the development of declarative memory

Imitation is an important means by which infants learn new behaviours. When infants do not have the opportunity to immediately reproduce observed actions, they may form a memory representation of the event which can guide their behaviour when a similar situation is encountered again. Imitation procedures can, therefore, provide insight into infant memory. The deferred imitation paradigm requires a modelled action to be reproduced following a delay, without prior motor practice. As such, deferred imitation procedures have been proposed to tap declarative memory abilities in non‐verbal populations such as infants. Contrary to the popular belief that infants form sparse or ill‐defined memories, deferred imitation research reveals that infants store and retrieve highly detailed memory representations. The specificity of detail encoded into the representation can, however, cause memory retrieval to fail at young ages. Developing the ability to identify event components which are central (the target stimulus) versus details which are peripheral (the exact context in which learning occurred) is therefore an important aspect of memory development. Using deferred imitation procedures to study the transition from constrained to flexible memory representations can thus facilitate our understanding of the development of declarative memory during the infancy period. Copyright © 2006 John Wiley & Sons, Ltd.     

Learning a procedure from multimedia instructions: The effects of film and practice

College students were taught to build a model helicopter from an assembly kit. Their instructions consisted of a narrated film (one viewing or two), hands-on practice using a model as a guide (one building or two), or a combination (see film first, build second; or build first, see film second). Performance on assembly from memory was assessed either immediately or after a 1-week delay. Both structural and functional measures were used. (A new structural measure is introduced here.) Performance was best immediately for groups who had hands-on practice, either twice, or in conjunction with a film. After a week, the group who practised first and saw the film second performed significantly better than all others. A theoretical framework, based on multimedia concept formation, is briefly presented to account for the results. In order for lasting concepts to be formed in memory, a precedence is suggested: motoric elements with their accompanying mental components should be put in first, followed by visual, followed by linguistic.     

The effects of adults' affective expression and direction of visual gaze on 12‐month‐olds' visual preferences for an object following a 5‐minute, 1‐day,or 1‐month delay

Between 12‐ and 14 months of age infants begin to use another's direction of gaze and affective expression in learning about various objects and events. What is not well understood is how long infants' behaviour towards a previously unfamiliar object continues to be influenced following their participation in circumstances of social referencing. In this experiment, we examined infants' sensitivity to an adult's direction of gaze and their visual preference for one of two objects following a 5‐min, 1‐day, or 1‐month delay. Ninety‐six 12‐month‐olds participated. For half of the infants during habituation (i.e., familiarization), the adults' direction of gaze was directed towards an unfamiliar object (look condition). For the remaining half of the infants during habituation, the adults' direction of gaze was directed away from the unfamiliar object (look‐away condition). All infants were habituated to two events. One event consisted of an adult looking towards (look condition) or away from (look‐away condition) an object while facially and vocally conveying a positive affective expression. The second event consisted of the same adult looking towards or away from a different object while conveying a disgusted affective expression. Following the habituation phase and a 5‐min, 1‐day, or 1‐month delay, infants' visual preference was assessed. During the visual preference phase, infants saw the two objects side by side where the adult conveying the affective expression was not visible. Results of the visual preference phase indicate that infants in the look condition showed a significant preference for object previously paired with the positive affect following a 5‐min and 1‐day delay. No significant visual preference was found in the look condition following a 1‐month delay. No significant preferences were found at any retention interval in the look‐away condition. Results are discussed in terms of early learning, social referencing, and early memory.     

Effects of delayed conditioned reinforcement in chain schedules.

The contingency between responding and stimulus change on a chain variable-interval 33-s, variable-interval 33-s, variable-interval 33-s schedule was weakened by interposing 3-s delays between either the first and second or the second and third links. No stimulus change signaled the delay interval and responses could occur during it, so the obtained delays were often shorter than the scheduled delay. When the delay occurred after the initial link, initial-link response rates decreased by an average of 77% with no systematic change in response rates in the second or third links. Response rates in the second link decreased an average of 59% when the delay followed that link, again with little effect on response rates in the first or third links. Because the effect of delaying stimulus change was comparable to the effect of delaying primary reinforcement in a simple variable-interval schedule, and the effect of the unsignaled delay was specific to the link in which the delay occurred, the results provide strong evidence for the concept of conditioned reinforcement.     

The effect of modeling and vicarious reinforcement upon the subsequent imitation of a socially approved response

This study tested whether modeling and positive vicarious reinforcement produced imitation of a socially approved behavior. Eighty-eight fourth-grade girls were divided into four groups: three experimental and one control. The experimental groups watched a video tape of a peer model drawing. In one condition the model was praised; in the second, no praise was given and a short interval elapsed before the S could model the behavior; in the third, no praise was given and the S could model the behavior immediately. The control group watched a blank screen. Significant modeling effects occurred among those Ss exposed to the tapes (p < .001). Positive vicarious reinforcement, however, did not further facilitate the modeling effect. The data were discussed in light of the practicality and feasibility of using modeling procedures in the schools.     

Neonatal imitation of tongue protrusion and mouth opening: Methodological aspects and evidence of early individual differences

The present work examines imitation of mouth opening and tongue protrusion in 32 full-term infants at three different occasions: When the infants are two to three days, three weeks, and three months old. The analysis focuses (1) on individual differences in imitative behaviour and (2) on how to operationalize the infants' responses. The overall group analysis revealed that imitation of tongue protrusion was statistically significant for both two- to three-day-old and three-week-old infants but not when the children had become three months old. No statistically significant effect was observed for imitation of mouth opening. Two different imitation indexes were constructed in order to assess individual differences in early imitative behaviour. Results show that short-term stability in imitative tendencies exists between the first and second observation. The results further reveal that methodological factors must be seriously considered when studying neonatal imitation: the overall imitation found for tongue protrusion is demonstrated to be dependent on how the infants' responses are coded.