Twelve-month-olds' understanding of prior actions and final goals

Twelve-month-olds were habituated to trials in which a grasping action preceded the holding of an object. Infants recovered looking to test events when a new object was held, but only when this was preceded by prior contact with the object.     

The ratio principle holds over a million-to-one range of illumination

Infant sensitivity to kinetic information specifying three-dimensional object shape was assessed using computer-generated random-dot displays. Four-month-old infants were habituated to displays of an object oscillating about two different axes on alternating trials. Following habituation, the infants were tested for recovery from habituation to a display of the same object and a novel object. Both test displays employed a new axis of rotation. The infants generalized habituation to the same object and increased their looking to the new object. These results provide evidence that infants are sensitive to motion-carried information specifying three-dimensional object shape, since the random-dot displays minimized static information that differentiated the two objects. These findings suggest that, at least by 4 months of age, infants can detect subtle differences in shape from purely kinetic information.     

Categorization in infancy based on novelty and co-occurrence

Abstract categories (i.e., groups of objects that do not share perceptual features, such as food) abound in everyday situations. The present looking time study investigated whether infants are able to distinguish between two abstract categories (food and toys), and how this ability may extend beyond perceived information by manipulating object familiarity in several ways. Test trials displayed 1) the exact familiarized objects paired as they were during familiarization, 2) a cross-pairing of these same familiar objects, 3) novel objects in the same category as the familiarized items, or 4) novel objects in a different category. Compared to the most familiar test trial (i.e., Familiar Category, Familiar Objects, Familiar Pairings), infants looked longer to all other test trials. Although there was a linear increase in looking time with increased novelty of the test trials (i.e., Novel Category as the most novel test trial), the looking times did not differ significantly between the Novel Category and Familiar Category, Unfamiliar Objects trials. This study contributes to our understanding of how infants form object categories based on object familiarity, object co-occurrence, and information abstraction.     

Binding feature dimensions in visual short-term memory

We explored several possible influences on binding in visual short-term memory (VSTM) performance. The task was to report whether a test object was the same (“old” trials) or different (“new” trials) from any of the sample objects seen a second ago. The objects were composed of two features that varied from continuous to discrete shapes and colors. In “old” trials the test object appeared either in the same or different position. In “new” trials the test object differed along both features, requiring storage of only one feature per object; along one feature, requiring no binding but storage of all features; or it was created by recombining features from the sample, which requires binding. Existing storage hypotheses are unable to explain the similar sensitivity (d′) obtained in the two last conditions when position remained the same and may suggest that links are created between positions and features. Highest sensitivity occurred when the test object remained at the same position, required no binding, and discrete features were used. Object-type × position, and feature combination × position interactions occurred, suggesting different storage modes depending on whether objects change position during retention.     

Six-month-olds’ ability to use linguistic cues when interpreting others’ pointing actions

The present research investigated whether six-month-olds who rarely produce pointing actions can detect the object-directedness and communicative function of others’ pointing actions when linguistic information is provided. In Experiment 1, infants were randomly assigned to either a novel-word or emotional-vocalization condition. They were first familiarized with an event in which an actor uttered either a novel label (novel-word condition) or exclamatory expression (emotional-vocalization condition) and then pointed to one of two objects. Next, the positions of the objects were switched. During test trials, each infant watched the new-referent event where the actor pointed to the object to which the actor had not pointed before or the old-referent event where the actor pointed to the old object in its new location. Infants in the novel-word condition looked reliably longer at the new-referent event than at the old-referent event, suggesting that they encoded the object-directedness of the actor’s point. In contrast, infants in the emotional-vocalization condition showed roughly equal looking times to the two events. To further examine infants’ understanding of the communicative aspect of an actor’s point using a different communicative context, Experiment 2 used an identical procedure to the novel-word condition in Experiment 1, except there was only one object present during the familiarization trials. When the familiarization trials did not include a contrasting object, we found that the communicative intention of the actor’s point could be ambiguous. The infants showed roughly equal looking times during the two test events. The current research suggests that six-month-olds understand the object-directedness and communicative intention of others’ pointing when presented with a label, but not when presented with an emotional non-speech vocalization.     

How infants relate looker and object: evidence for a perceptual learning account of gaze following in infancy

In two experiments, it was investigated how preverbal infants perceive the relationship between a person and an object she is looking at. More specifically, it was examined whether infants interpret an adult's object-directed gaze as a marker of an intention to act or whether they relate the person and the object via a mechanism of associative learning. Fourteen-month-old infants observed an adult gazing repeatedly at one of two objects. When the adult reached out to grasp this object in the test trials, infants showed no systematic visual anticipations to it (i.e. first visual anticipatory gaze shifts) but only displayed longer looking times for this object than for another before her hand reached the object. However, they showed visual anticipatory gaze shifts to the correct action target when only the grasping action was presented. The second experiment shows that infants also look longer at the object a person has been gazing at when the person is still present, but is not performing any action during the test trials. Looking preferences for the objects were reversed, however, when the person was absent during the test trials. This study provides evidence for the claim that infants around 1 year of age do not employ other people's object-directed gaze to anticipate future actions, but to establish person-object associations. The implications of this finding for theoretical conceptions of infants' social-cognitive development are discussed.     

Changing within-trial array location and target object position enhances rats’ (Rattus norvegicus) missing object recognition accuracy

Six rats were trained to find a previously missing target or 'jackpot' object in a square array of four identical or different objects (the test segment of a trial) after first visiting and collecting sunflower seeds from under the other three objects (the study segment of a trial). During training, objects' local positions within the array and their global positions within the larger foraging array were varied over trials but were not changed between segments within a trial. Following this training, rats were tested on their accuracy for finding the target object when a trial's test array was sometimes moved to a different location in the foraging arena or when the position of the target object within the test array had been changed. Either of these manipulations initially slightly reduced rats' accuracy for finding the missing object but then enhanced it. Relocating test arrays of identical objects enhanced rats' performance only after 10-min inter-segment intervals (ISIs). Relocating test arrays of different objects enhanced rats' performance only after 2-min ISIs. Rats also improved their performance when they encountered the target object in a new position in test arrays of different objects. This enhancement effect occurred after either 2- or 30-min ISIs. These findings suggest that rats separately retrieved a missing (target) object's spatial and non-spatial information when they were relevant but not when they were irrelevant in a trial. The enhancement effects provide evidence for rats' limited retrieval capacity in their visuo-spatial working memory.     

Learning in repeated visual search

Visual search (e.g., finding a specific object in an array of other objects) is performed most effectively when people are able to ignore distracting nontargets. In repeated search, however, incidental learning of object identities may facilitate performance. In three experiments, with over 1,100 participants, we examined the extent to which search could be facilitated by object memory and by memory for spatial layouts. Participants searched for new targets (real-world, nameable objects) embedded among repeated distractors. To make the task more challenging, some participants performed search for multiple targets, increasing demands on visual working memory (WM). Following search, memory for search distractors was assessed using a surprise two-alternative forced choice recognition memory test with semantically matched foils. Search performance was facilitated by distractor object learning and by spatial memory; it was most robust when object identity was consistently tied to spatial locations and weakest (or absent) when object identities were inconsistent across trials. Incidental memory for distractors was better among participants who searched under high WM load, relative to low WM load. These results were observed when visual search included exhaustive-search trials (Experiment 1) or when all trials were self-terminating (Experiment 2). In Experiment 3, stimulus exposure was equated across WM load groups by presenting objects in a single-object stream; recognition accuracy was similar to that in Experiments 1 and 2. Together, the results suggest that people incidentally generate memory for nontarget objects encountered during search and that such memory can facilitate search performance.     

Guidance of attention to objects and locations by long-term memory of natural scenes

Four flicker change-detection experiments demonstrate that scene-specific long-term memory guides attention to both behaviorally relevant locations and objects within a familiar scene. Participants performed an initial block of change-detection trials, detecting the addition of an object to a natural scene. After a 30-min delay, participants performed an unanticipated 2nd block of trials. When the same scene occurred in the 2nd block, the change within the scene was (a) identical to the original change, (b) a new object appearing in the original change location, (c) the same object appearing in a new location, or (d) a new object appearing in a new location. Results suggest that attention is rapidly allocated to previously relevant locations and then to previously relevant objects. This pattern of locations dominating objects remained when object identity information was made more salient. Eye tracking verified that scene memory results in more direct scan paths to previously relevant locations and objects. This contextual guidance suggests that a high-capacity long-term memory for scenes is used to insure that limited attentional capacity is allocated efficiently rather than being squandered.     

Picture–object recognition in the tortoise Chelonoidis carbonaria

To recognize that a picture is a representation of a real-life object is a cognitively demanding task. It requires an organism to mentally represent the concrete object (the picture) and abstract its relation to the item that it represents. This form of representational insight has been shown in a small number of mammal and bird species. However, it has not previously been studied in reptiles. This study examined picture–object recognition in the red-footed tortoise (Chelonoidis carbonaria). In Experiment 1, five red-footed tortoises were trained to distinguish between food and non-food objects using a two-alternative forced choice procedure. After reaching criterion, they were presented with test trials in which the real objects were replaced with color photographs of those objects. There was no difference in performance between training and test trials, suggesting that the tortoises did see some correspondence between the real object and its photographic representation. Experiment 2 examined the nature of this correspondence by presenting the tortoises with a choice between the real food object and a photograph of it. The findings revealed that the tortoises confused the photograph with the real-life object. This suggests that they process real items and photographic representations of these items in the same way and, in this context, do not exhibit representational insight.     

Can 9.5-month-old infants attribute to an agent a disposition to perform a particular action on objects?

The present research examined whether 9.5-month-old infants can attribute to an agent a disposition to perform a particular action on objects, and can then use this disposition to predict which of two new objects - one that can be used to perform the action and one that cannot - the agent is likely to reach for next. The infants first received familiarization trials in which they watched an agent slide either three (Experiments 1 and 3) or six (Experiment 2) different objects forward and backward on an apparatus floor. During test, the infants saw two new identical objects placed side by side: one stood inside a short frame that left little room for sliding, and the other stood inside a longer frame that left ample room for sliding. The infants who saw the agent slide six different objects attributed to her a disposition to slide objects: they expected her to select the "slidable" as opposed to the "unslidable" test object, and they looked reliably longer when she did not. In contrast, the infants who saw the agent slide only three different objects looked about equally when she selected either test object. These results add to recent evidence that infants in the first year of life can attribute dispositions to agents, and can use these dispositions to help predict agents' actions in new contexts.     

Preschoolers' perspective taking in word learning: do they blindly follow eye gaze?

When learning new words, do children use a speaker's eye gaze because it reveals referential intent? We conducted two experiments that addressed this question. In Experiment 1, the experimenter left while two novel objects were placed where the child could see both, but the experimenter would be able to see only one. The experimenter returned, looked directly at the mutually visible object, and said either, "There's the [novel word]!" or "Where's the [novel word]?" Two- through 4-year-olds selected the target of the speaker's gaze more often on there trials than on where trials, although only the older children identified the referent correctly at above-chance levels on trials of both types. In Experiment 2, the experimenter placed a novel object where only the child could see it and left while the second object was similarly hidden. When she returned and asked, "Where's the [novel word]?" 2- through 4-year-olds chose the second object at above-chance levels. Preschoolers do not blindly follow gaze, but consider the linguistic and pragmatic context when learning a new word.     

Object-centred spatial reference in 4-month-old infants

An appreciation of object-centred spatial relations involves representing a 'within-object' spatial relation across changes in the object orientation. This representational ability is important in adult object recognition [Biederman, I. (1987). Recognition-by-components: A theory of human image understanding. Psychological Review, 94, 115-147; Marr, D., & Nishihara, H. K. (1978). Representation and recognition of the spatial organisation of three-dimensional structure. Proceedings of the Royal Society of London, Series B (Biological Sciences), 200, 269-294; Tarr, M. J., & Pinker, S. (1990). When does human object recognition use a viewer-centred reference frame? Psychological Science, 1, 253-256] and is also thought to be a fundamental component of the mature object concept [Piaget, J. (1954). The Construction of Reality in the Child. Routledge & Kegan-Paul: London, UK. (Originally published in French in 1937)]. An experiment is reported in which eighteen 4-month-old infants were familiarised to a specific spatial relation within an object, across six different orientations of the object. On subsequent test trials the object was presented to the infants in an entirely novel orientation. Between successive test trials the within-object spatial relation was alternated between novel and familiar. The infants demonstrated significant sensitivity of their looking to both the novelty of the stimuli and the order in which novel and familiar stimuli were presented. It is concluded that by 4 months of age infants are able to form object-centred spatial frames of reference. These findings are discussed in the light of our current understanding of the development of object representation during infancy.     

New objects dominate luminance transients in setting attentional priority.

Both the sudden appearance of an object and sudden changes in existing object features influence priority in visual search. However, direct comparisons of these influences have not been made under controlled conditions. In 5 visual search experiments, new object onsets were compared directly with changes in the luminance of old objects. Factors included the luminance contrast of items against the background, the magnitude of luminance change, and the probability that these changes were associated with the target item. New objects were consistently more effective in guiding search, such that a new item with very low luminance contrast was equivalent to an old item undergoing a large change in luminance. An important exception was an old item changing in contrast and polarity, which was as effective as the appearance of a new object. This indicates that search priority is biased toward object rather than situational changes.     

An exploratory analysis of task-interspersal procedures while teaching object labels to children with autism

Research has demonstrated that interspersing mastered tasks with new tasks facilitates learning under certain conditions; however, little is known about factors that influence the effectiveness of this treatment strategy. The initial purpose of the current investigation was to evaluate the effects of similar versus dissimilar interspersed tasks while teaching object labels to children diagnosed with autism or developmental delays. We then conducted a series of exploratory analyses involving the type of reinforcer delivered for correct responses on trials with unknown or known object labels. Performance was enhanced under the interspersal condition only when either brief praise was delivered for all correct responses or presumably more preferred reinforcers were provided for performance on known trials rather than on unknown trials.     

The Disambiguation Prediction Effect

ABSTRACT

Children tend to select a novel object rather than a familiar object when asked to identify the referent of a novel label. Current accounts of this so-called disambiguation effect do not address whether children have a general metacognitive representation of this way of determining the reference of novel labels. In two experiments (each N = 48), three- and four-year-olds received a prediction task that required such a representation. In the initial phase, children completed four disambiguation test trials that were presented as instances of the same “game.” In the next phase, they received four additional trials. These differed only in that before the label was presented, children were asked to predict which object “was going to be right.” On the first prediction trial, most four-year-olds predicted the novel object, whereas most three-year-olds did not. On subsequent trials, despite having received feedback regarding predictions, three-year-olds showed no tendency to begin to predict the novel object, whereas most four-year-olds continued to make this prediction. These findings add to the evidence that most children develop a general metacognitive representation of their tendency to map novel labels onto novel rather than familiar objects some time around their fourth birthday.     

Televised social interaction and object learning in 14- and 18-month-old infants

We examined object learning in infants who viewed a televised adult speaking about a novel toy in videos that varied in the social cues provided. Novelty preference in following test trials differed as a function of televised social cues in 18-month-old, but not 14-month-old infants.     

Memory for Objects and Positions: Delayed Non-matching-to-sample in Storing and Non-storing Tits

An operant delayed-non-matching-to-sample task using computer-presented images was used to test memory for position and object (shape and colour) cues in four species of tit (Parus), two food-storing species (P. palustris and P. ater) and two non-storing species (P. major and P. caeruleus). Both storers and non-storers performed successfully at retention intervals as long as 100 sec on all trial types, and there were no significant differences in performance between the two groups on any of the trial types. Performance by both groups was highest on trials in which both object and position cues were available and poorest on trials when object cues only were relevant. These data do not provide support for the hypothesis that food storers have a better memory for spatial cues than do non-storers.     

What do infants remember when they forget? Location and identity in 6-month-olds' memory for objects

What does an infant remember about a forgotten object? Although at age 6 months, infants can keep track of up to three hidden objects, they can remember the featural identity of only one. When infants forget the identity of an object, do they forget the object entirely, or do they retain an inkling of it? In a looking-time study, we familiarized 6-month-olds with a disk and a triangle placed on opposite sides of a stage. During test trials, we hid the objects one at a time behind different screens, and after hiding the second object, we removed the screen where the first object had been hidden. Infants then saw the expected object, the unexpected other object, or the empty stage. Bayes factor analysis showed that although the infants did not notice when the object changed shape, they were surprised when it vanished. This finding indicates that infants can represent an object without its features.     

Selective attention meets spontaneous recognition memory: Evidence for effects at retrieval

Previous research on the effects of Divided Attention on recognition memory have shown consistent impairments during encoding but more variable effects at retrieval. The present study explored whether effects of Selective Attention at retrieval and subsequent testing were parallel to those of Divided Attention. Participants studied a list of pictures and then had a recognition memory test that included both full attention and selective attention (the to be responded to object was overlaid atop a blue outlined object) trials. All participants then completed a second recognition memory test. The results of 2 experiments suggest that subsequent tests consistently show impacts of the status of the ignored stimulus, and that having an initial test changes performance on a later test. The results are discussed in relation to effect of attention on memory more generally as well as spontaneous recognition memory research.