Precursors to the development of intention at 6 months: Understanding people and their actions.

Under investigation was whether 6-month-old infants expect people to behave differently toward persons and inanimate objects. Infants were randomly assigned to experimental and control conditions. In the experimental conditions, infants were habituated to an actor who either talked to or reached for and swiped with something hidden behind an occluder. In the test events the actor was occluded, but the infants were shown either a person or an object. In the control condition, infants only saw the person or object stimulus. Results showed that infants who had been habituated to an actor who was talking looked longer at the object, and infants who had been habituated to an actor who was reaching and swiping looked longer at the person. No difference in looking at the stimuli was observed in the control condition. This suggests that infants expect people's actions to be related to objects in ways that are continuous with more mature, intentional understandings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory-visual integration of temporal relations in infants.

A total of 100 3–4 mo old infants in 2 experiments were assigned to 1 of 2 groups: one group was first presented with temporally synchronous auditory and visual signals during habituation trials and then nonsynchronous signals during recovery; the other groups received the opposite sequence. The auditory and visual signals were spatially congruous in Exp I, but were separated in Exp II. Since the pulse rate of the visual stimuli was changed for the nonsynchronous trials, a control group was tested that received only the light during habituation and recovery trials. The groups initially presented synchronous signals showed habituation and recovery. Neither group presented nonsynchronous stimuli showed recovery. The group with the spatially separated sources habituated, while the group with the spatially congruous signals did not. Results suggest that infants coordinate the temporal relations. (French abstract) (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of infants' use of continuity cues in their perception of causality.

Two experiments investigated the role of continuity cues in infants' perception of launching events as causal. Exp 1 showed that 7-mo-old infants can use spatial and temporal contiguity to perceive causality: Infants who were habituated to a causal event dishabituated to novel noncausal events, in which either spatial or temporal contiguity was violated, and those who were habituated to a noncausal event dishabituated to a novel causal but not a novel noncausal event. Experiment 2 showed that 10-mo-olds, but not 7-mo-olds, perceived the causality of launching events in which the objects moved along dissimilar paths. Thus, younger infants do not appear to attend to causality when the objects move along different paths. Results are discussed in terms of the development of the use of continuity cues in causal judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A negative order-repetition priming effect: Inhibition of order in unattended auditory sequences?

A novel negative priming (NP) effect is reported in which serial recall for a sequence of visually presented digits was poorer if the same sequence was presented as an irrelevant auditory sequence on the previous trial (Experiments 1 and 2). The effect was enhanced when attention was divided between the to-be-repeated auditory sequence and the concurrent to-be-remembered (TBR) sequence (Experiment 3). When the TBR sequences were also presented auditorily, NP arose only when the repeated TBR sequence was in the same voice as the previous irrelevant sequence; a voice mismatch produced positive priming (Experiment 4). The results suggest that the order of auditory events is registered preattentively and that inhibition may be applied to the acoustic transitions between irrelevant events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional priming and visual search in pigeons.

Advance information about a target's identity improved visual search efficiency in pigeons. Experiments 1 and 2 compared information supplied by visual cues with information supplied by trial sequences. Reaction times (RTs) were lower when visual cues signaled a single target rather than two. RTs were lower (Experiment 1) or accuracy improved (Experiment 2) when a sequence of trials presented a single target rather than a mixture of 2. Experiments 3, 4, and 5 considered the selectivity of visual priming by introducing probe trials that reversed the usual cue–target relationship. RT was higher following such miscues than following the usual 1- or 2-target cuing relationships (Experiment 3); the miscuing effect persisted over variations in the target's concealment (Experiments 4 and 5), but did not occur when the target was presented alone (Experiment 4). Findings indicate that priming modifies an attentional mechanism and suggest that this effect accounts for search images. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Young infants' generalization of emotional expressions: Effects of familiarity.

From birth, infants are exposed to a wealth of emotional information in their interactions. Much research has been done to investigate the development of emotion perception, and factors influencing that development. The current study investigates the role of familiarity on 3.5-month-old infants' generalization of emotional expressions. Infants were assigned to one of two habituation sequences: in one sequence, infants were visually habituated to parental expressions of happy or sad. At test, infants viewed either a continuation of the habituation sequence, their mother depicting a novel expression, an unfamiliar female depicting the habituated expression, or an unfamiliar female depicting a novel expression. In the second sequence, a new sample of infants was matched to the infants in the first sequence. These infants viewed the same habituation and test sequences, but the actors were unfamiliar to them. Only those infants who viewed their own mothers and fathers during the habituation sequence increased looking. They dishabituated looking to maternal novel expressions, the unfamiliar female's novel expression, and the unfamiliar female depicting the habituated expression, especially when sad parental expressions were followed by an expression change to happy or to a change in person. Infants are guided in their recognition of emotional expressions by the familiarity of their parents, before generalizing to others. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The early development of object knowledge: A study of infants’ visual anticipations during action observation.

This study examined the developing object knowledge of infants through their visual anticipation of action targets during action observation. Infants (6, 8, 12, 14, and 16 months) and adults watched short movies of a person using 3 different everyday objects. Participants were presented with objects being brought either to a correct or to an incorrect target location (e.g., cup to mouth, phone to ear vs. cup to ear, brush to mouth). When observing the action sequences, infants as well as adults showed anticipatory fixations to the target areas of the displayed actions. For all infant age-groups, there were differences in anticipation frequency between functional and nonfunctional object–target combinations. Adults exhibited no effect of object–target combination, possibly because they quickly learned and flexibly anticipated the target area of observed actions, even when they watched objects being brought to incorrect target areas. Infants, however, had difficulties anticipating to incorrect target locations for familiar objects. Together, these findings suggest that by 6 months of age, infants have acquired solid knowledge about objects and the actions associated with them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infant imitation: The sensory-motor agenda.

Six different actions were demonstrated by the 2nd author to 9 infants once a month between the ages of 6 and 12 mo. Each action was presented many times, with each trial contingent on the S's making eye contact with the experimenter. From videotapes, 21 categories (CAs) of infant behavior were coded continuously. Each CA could be considered a component act or feature of one of the modeled actions. All CAs were coded during all parts of the session: baseline periods, trials of the tasks of which they were features, and trials of the other tasks. Ss did not confine their performance of features to the relevant trials as construed by the authors, but they did accelerate or introduce features for the first time during those trials. Analysis showed that the Ss "worked up to" precise imitations by accommodating themselves to the features in a consistent order over both months and trials. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term recognition memory for faces assessed by visual paired comparison in 3- and 6-month-old infants.

It has been argued that operant conditioning is the only type of long-term memory present in infants prior to 6 months of age. In this study, memory for faces was investigated in 3- and 6-month-old infants with a visual paired-comparison task. In Experiment 1, infants were habituated to a face presented in different poses; recognition was assessed after a 2-min or a 24-hr retention interval. The 6-month-old infants and the male but not the female 3-month-old infants exhibited novelty preferences. A 2nd experiment showed that 3-month-old female infants were delayed relative to male infants in their face-processing ability rather than in their memory capacity. The results of Experiment 3 demonstrated in 3-month-olds an electrophysiological correlate of delayed recognition memory. These findings are discussed in the context of the neural systems thought to be involved in visual recognition memory (but not in procedural memory), namely the limbic system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrated and independent learning of hand-related constituent sequences.

In almost all daily activities fingers of both hands are used in coordinated succession. The present experiments explored whether learning in such tasks pertains not only to the overall sequence spanning both hands but also to the constituent sequences of each hand. In a serial reaction time task, 2 repeating hand-related sequences were intertwined, so that actions of one hand alternated with actions of the other hand. Integrated learning of the overall sequence was weak when the constituent sequences were uncorrelated (Experiment 1) and massive when they were correlated (Experiment 2). Both experiments yielded evidence suggesting partly independent learning of the hand-related sequences. There were no reliable indications of intermanual transfer of this hand-related sequence knowledge. The findings suggest that after sufficient training of coordinated action sequences involving several limbs, a part of the acquired sequence knowledge begins to be represented in an effector-specific manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants learn about objects from statistics and people.

In laboratory experiments, infants are sensitive to patterns of visual features that co-occur (e.g., Fiser & Aslin, 2002). Once infants learn the statistical regularities, however, what do they do with that knowledge? Moreover, which patterns do infants learn in the cluttered world outside of the laboratory? Across 4 experiments, we show that 9-month-olds use this sensitivity to make inferences about object properties. In Experiment 1, 9-month-old infants expected co-occurring visual features to remain fused (i.e., infants looked longer when co-occurring features split apart than when they stayed together). Forming such expectations can help identify integral object parts for object individuation, recognition, and categorization. In Experiment 2, we increased the task difficulty by presenting the test stimuli simultaneously with a different spatial layout from the familiarization trials to provide a more ecologically valid condition. Infants did not make similar inferences in this more distracting test condition. However, Experiment 3 showed that a social cue did allow inferences in this more difficult test condition, and Experiment 4 showed that social cues helped infants choose patterns among distractor patterns during learning as well as during test. These findings suggest that infants can use feature co-occurrence to learn about objects and that social cues shape such foundational learning in distraction-filled environments. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Two-month-old infants' sensitivity to changes in arbitrary syllable–object pairings: The role of temporal synchrony.

To explore early lexical development, the authors examined infants' sensitivity to changes in spoken syllables and objects given different temporal relations between syllable–object pairings. In Experiment 1, they habituated 2-month-olds to 1 syllable, /tah/ or /gah/, paired with an object in synchronous (utterances coincident with object motions, N = 16) or asynchronous (utterances erratic relative to object motions, N = 16) conditions. In the asynchronous condition, the audio track preceded or succeeded the visual track by 1,200 ms. On test, infants in the synchronous condition alone detected the changes. Post hoc computational analyses confirmed lower time separation, interpreted as greater synchrony, between peaks and onsets–offsets of visual motion and audio energy in the synchronous relative to the asynchronous condition. Further examining lexical development, in Experiment 2 they habituated 2-month-olds (N = 16) to two synchronous syllable–object pairs and tested them on switch versus same pairings. Infants failed to detect the switch in the pairings. These results suggest that 2-month-olds use synchrony to detect changes in one novel syllable–object pairing at a time, providing a basis for further word mapping development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning and discrimination of audiovisual events in human infants: The hierarchical relation between intersensory temporal synchrony and rhythmic pattern cues.

This study examined 4- to 10-month-old infants' perception of audio-visual (A-V) temporal synchrony cues in the presence or absence of rhythmic pattern cues. Experiment 1 established that infants of all ages could successfully discriminate between two different audiovisual rhythmic events. Experiment 2 showed that only 10-month-old infants detected a desynchronization of the auditory and visual components of a rhythmical event. Experiment 3 showed that 4- to 8-month-old infants could detect A-V desynchronization but only when the audiovisual event was nonrhythmic. These results show that initially in development infants attend to the overall temporal structure of rhythmic audiovisual events but that later in development they become capable of perceiving the embedded intersensory temporal synchrony relations as well. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Source Recall Enhances Children's Discrimination of Seen and Heard Events.

The effects of rehearsing actions by source (slideshow vs. story) and of test modality (picture vs. verbal) on source monitoring were examined. Seven- to 8-year-old children (N = 30) saw a slideshow event and heard a story about a similar event. One to 2 days later, they recalled the events by source (source recall), recalled the events without reference to source (no-source-cue recall), or engaged in no recall. Seven to 8 days later, all children received verbal and picture source-monitoring tests. Children in the source recall group were less likely than children in the other groups to claim they saw actions merely heard in the story. No-source-cue recall impaired source identification of story actions. The picture test enhanced recognition, but not source monitoring, of slide actions. Increasing the distinctiveness of the target events (Experiment 2) allowed the picture test to facilitate slideshow action discrimination by children in the no-recall group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for multiple visual ensembles in infancy.

The number of individual items that can be maintained in working memory is limited. One solution to this problem is to store representations of ensembles that contain summary information about large numbers of items (e.g., the approximate number or cumulative area of a group of many items). Here we explored the developmental origins of ensemble representations by asking whether infants represent ensembles and, if so, how many at one time. We habituated 9-month-old infants to arrays containing 2, 3, or 4 spatially intermixed colored subsets of dots, then asked whether they detected a numerical change to one of the subsets or to the superset of all dots. Experiment Series 1 showed that infants detected a numerical change to 1 of the subsets when the array contained 2 subsets but not 3 or 4 subsets. Experiment Series 2 showed that infants detected a change to the superset of all dots no matter how many subsets were presented. Experiment 3 showed that infants represented both the approximate number and the cumulative surface area of these ensembles. Our results suggest that infants, like adults (Halberda, Sires, & Feigenson, 2006), can store quantitative information about 2 subsets plus the superset: a total of 3 ensembles. This converges with the known limit on the number of individual objects infants and adults can store and suggests that, throughout development, an ensemble functions much like an individual object for working memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Perceptual completion of surfaces in infancy.

Two experiments provide evidence that 4-month-old infants perceive background surfaces as continuous behind occluding objects. Infants were shown a partly hidden background surface either for a brief period of familiarization (Experiment 1) or until they met a criterion of habituation (Experiment 2). The infants were then tested with nonoccluded surfaces that were either continuous or interrupted by a gap where the occluder had been. The infants in each study looked longer at the interrupted than at the continuous surface, relative to infants in baseline controls, which suggests that the partly hidden surface was perceived as continuous. Contrasting findings were obtained in a third experiment, in which infants were habituated to a partly hidden surface that stood in front of a background so that its edges were visible: Infants gave no evidence of perceiving the foreground surface as continuous behind the occluder. These experiments provide evidence that infants perceive a surface as continuous only if it serves as the background of a scene. The results are discussed in relation to figure-ground perception in pictures and surface layouts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural correlates of cross-modal recognition memory by 8-month-old human infants.

Examined the neural correlates of cross-modal recognition memory in 8-mo-old infants by using ERPs. Testing began by having all Ss feel (but not see) an object for 60 sec. Test trials then followed. Infants in Condition 1 received 15 presentations of a picture of the familiar object, followed by alternating pictures of that object and a novel object. Infants in Condition 2 received 15 presentations of a picture of the novel object, followed by the same test sequence as infants in Condition 1. Infants in Condition 3 were presented with 2 test trials during which looking times were recorded to pictures of the familiar and novel objects; they then received the same test sequence as infants in Conditions 1 and 2. Infants in Condition 4 were presented only with the same test sequence as infants in Conditions 1, 2, and 3. Only in Conditions 1 and 4 was a late positive slow wave invoked by the novel object (indicative of recognition memory), although infants in Condition 3 did show a significant looking preference for the novel object. These results are contrasted with previous studies examining the neural correlates of visual recognition memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infant discrimination of faces in naturalistic events: Actions are more salient than faces.

Despite the fact that faces are typically seen in the context of dynamic events, there is little research on infants' perception of moving faces. L. E. Bahrick, L. J. Gogate, and I. Ruiz (2002) demonstrated that 5-month-old infants discriminate and remember repetitive actions but not the faces of the women performing the actions. The present research tested an attentional salience explanation for these findings: that dynamic faces are discriminable to infants, but more salient actions compete for attention. Results demonstrated that 5-month-old infants discriminated faces in the context of actions when they had longer familiarization time (Experiment 1) and following habituation to a single person performing 3 different activities (Experiment 2). Further, 7-month-old infants who have had more experience with social events also discriminated faces in the context of actions. Overall, however, discrimination of actions was more robust and occurred earlier in processing time than discrimination of dynamic faces. These findings support an attentional salience hypothesis and indicate that faces are not special in the context of actions in early infancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual experience influences 12-month-old infants' perception of goal-directed actions of others.

In the present study, we investigated whether infants' own visual experiences affected their perception of the visual status of others engaging in goal-directed actions. In Experiment 1, infants viewed video clips of successful and failed goal-directed actions performed by a blindfolded adult, with half the infants having previously experienced being blindfolded. The results showed that 12-month-old infants who were previously blindfolded preferred to look longer at the demonstrator's successful actions, whereas no such preference was observed in 8-month-old infants. In Experiment 2, infants watched the same 2 actions when the adult demonstrator was not blindfolded. The responses of 12-month-old infants were the opposite of those observed in Experiment 1: They showed a preference for the failed actions. These findings suggest that previous experience influenced the subsequent perception of others' goal-directed actions in the 12-month-old infants. We favor the interpretation that the preference for the successful actions in the 12-months-old infants provided with blindfolded experience demonstrates the influence of perceptual experience on considering the visual status of others engaging in goal-directed actions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The relation between infants' activity with objects and attention to object appearance.

The authors examined the relation between infants' motor skills and attention to objects features in events in which a hand acted on an object (e.g., squeezed it) that then produced a sound (e.g., squeaking). In this study, 6- to 7-month-old infants (N = 41) were habituated to a single event and then tested with changes in appearance and action. Infants robustly responded to changes in action, but as a group did not respond to changes in appearance. Moreover, more skilled activity with objects during naturalistic play was associated with longer looking in response to a change in appearance, but not to a change in action. Implications for the relation between perception and action in infancy are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)