Recognition of static and dynamic images of depth-rotated human faces by pigeons

In three experiments, we examined pigeons’ recognition of video images of human faces. In Experiment 1, pigeons were trained to discriminate between frontal views of human faces in a go/no-go discrimination procedure. They then showed substantial generalization to novel views, even though human faces change radically as viewpoint changes. In Experiment 2, the pigeons tested in Experiment 1 failed to transfer to the faces dynamically rotating in depth. In Experiment 3, the pigeons trained to discriminate the dynamic stimuli showed excellent transfer to the corresponding static views, but responses to the positive faces decreased at novel viewpoints outside the range spanned by the dynamic stimuli. These results suggest that pigeons are insensitive to the three-dimensional properties of video images. Consideration is given to the nature of the task, relating to the identification of three-dimensional objects and to perceptual classifications based on similarity judgments.     

The effect of prior practice on memory reactivation and generalization

Three experiments examined the effect of practice on memory performance by 18-month-old infants. Infants were tested using an imitation paradigm; an adult demonstrated a series of actions with objects and infants were given the opportunity to reproduce those actions following a delay. Some infants practiced the target actions before the retention interval (practice) and some did not (no practice). In Experiment 1, a reminder treatment alleviated forgetting by infants who practiced but failed to alleviate forgetting by infants who did not practice. In Experiments 2A and 2B, infants who practiced generalized to novel test stimuli after a 24-hr delay, whereas infants without practice did not. Results suggest practice influences the accessibility and generality of infants' memories.     

Delay-induced bias in children's memory for location

Two experiments examined how imposing a delay between learning and reproducing locations influences children's memory for location. In Experiment 1, ninety-six 7-, 9-, and 11-year-old children and adults learned the locations of 20 objects in an open, square box divided into four regions by opaque walls. During test, participants attempted to place the objects in the correct locations without the aid of the dots that had marked the locations or the boundaries that had divided the space. The test phase began either immediately following learning or following a 12-min delay. As predicted by the Category-Adjustment model, bias toward category centers increased significantly following an intervening delay. Moreover, the magnitude of categorical bias followed a systematic U-shaped developmental pattern. Results from a second study (N = 72) replicated this developmental pattern. Discussion focuses on the implications of these results for understanding how children and adults remember locations.     

Intermodal Perception of Adult and Child Faces and Voices by Infants

This research investigated the ability of 4- and 7-month-old infants to match unfamiliar, dynamic faces and voices on the basis of age or maturity. In Experiment 1, infants received videotaped trials of an adult and a child of the same gender, side by side, speaking a nursery rhyme in synchrony with one another. The voice to one and then the other face was played in synchrony with the movements of both faces in a random order across 12 trials. On one block of 6 trials a man and a boy were presented, and on the other block a woman and a girl. Results indicated significant matching of the faces and voices at both ages, and the infant's prior experience with children appeared to facilitate matching at 7 months. Further, a visual preference for the children's faces was found. Experiment 2 assessed matching to the same events by 7-month-olds, only with the faces inverted. Results indicated no evidence of matching; however, the visual preference for the children's faces was replicated. Together, the findings suggest that infants are able to detect invariant intermodal relations specifying the age or maturity of a person's face and voice. This matching was most likely based on information that was degraded by inverting the faces, including invariant relations between the sound of the voice and configurational aspects of the face, or between temporal aspects of the voice and the relative motion of facial features.     

It clicks when it is rolled and it squeaks when it is squeezed: what 10-month-old infants learn about object function

Function has been considered important in numerous literatures in the study of cognitive development, yet little is known about what and how infants learn about function. Five experiments examined what 10-month-old infants (N=80) learn about functions that involve a sound produced when an object is acted on. Infants habituated to a single object (Experiment 1) or multiple objects that performed the same function (Experiment 2) learned both the actions and the sounds. Infants did not appear to learn relations between actions and sounds (Experiment 3) or appearances and sounds (Experiment 4), although they did learn the relations between appearances and actions (Experiment 5). These results are discussed in terms of how infants learn about object function.     

The Organization of Reactivated Memory in Infancy

The specificity of memory retrieval by 3-month-old infants was examined in 3 experiments. All infants were trained in the mobile conjugate reinforcement paradigm to kick their feet to produce movement in an overhead crib mobile and were tested 2 weeks later. 24 hours prior to the test, subjects received a 3-min reminder treatment. The results of Experiment 1 demonstrated that only the moving training mobile alleviated forgetting after the 2-week retention interval; forgetting was not alleviated by exposure to the stationary training mobile or to the mobile stands and ribbon alone. The results of Experiments 2 and 3 demonstrated that, once retrieved, the reactivated memory was highly specific to the conditions of original training. Furthermore, the memory attributes that were the last to be forgotten (e.g., the general or global features) were the first to be retrieved following the reminder treatment. Conversely, those memory attributes that were forgotten first (e.g., the specific or local details) were the last to be retrieved. These findings have important implications for infant memory retrieval, reminiscence, and infantile amnesia.     

Parsing Items into Separate Categories: Developmental Change in Infant Categorization

Three experiments report developmental change in infants' tendency to parse exemplars into separate categories. In Experiment 1, a familiarization-novelty preference procedure was used. Fifty-four 4-, 7-, and 10-month-old infants were familiarized with members of two basic-level animal categories (cats and horses) and tested with novel members of the familiarized categories and with members of a third category (dogs). In Experiment 2, a habituation-dishabituation procedure was used. Forty-eight 7- and 10-month-old infants were habituated to examples of both male and female faces and tested with novel gender-typical and gender-ambiguous faces. In both experiments, 10-month-old infants appeared to form differentiated categories, whereas younger infants formed a single category to include the range of items presented during familiarization. Experiment 3 ruled out a priori stimulus preferences as an explanation for the 10-month findings in Experiment 2.     

Recognition of moving video images of conspecifics by pigeons: Effects of individuals, static and dynamic motion cues, and movement

Two groups of pigeons were trained with a go/no-go procedure to discriminate video images of conspecifics based on the individuals or else on their actions. Both groups showed rapid acquisition, and the discrimination transferred to new scenes in Experiment 1 and to static scenes in Experiment 2. In Experiment 3, experimentally naive pigeons were trained to discriminate video images of particular birds showing different actions. Transfer to novel scenes, including a new bird and a new motion, revealed the dominance of motion as a cue to discriminate video images. In Experiment 4, the pigeons trained to discriminate video scenes of 2 pigeons showing a variety of activities successfully recognized these stimuli regardless of whether the video was played forward or backward, and transferred the discrimination to still scenes. The findings suggest that pigeons’ discrimination of video images is primarily based on information that is invariant across static and dynamic conditions.     

Perception of pictorial human faces by baboons: Effects of stimulus orientation on discrimination performance

The effect of stimulus rotation was assessed in four Guinea baboons (Papio papio), using pictures of familiar human faces presented in a computerized go/no-go task. In Experiment 1, 2 baboons were initially trained to discriminate upright faces, and 2 others were trained to discriminate upside-down faces. For the two groups, postlearning discrimination was impaired when the training faces were rotated 180°. In Experiment 2, upright and upside-down priming faces appeared prior to the display of target faces. For the two groups, response times were faster when the prime and the target faces had the same orientations than when they were depicted under different orientations. Finally, Experiments 3 and 4 identified variations in facial contours as the most salient discriminative cue controlling performance in 2 baboons. Altogether, our results provide no evidence that the baboons processed the pictures as representations of faces. It is suggested that the effect of rotation derived from the encoding of the pictorial faces as meaningless mono-oriented shapes, rather than as natural human faces.     

Recognition of Moving and Static Faces by Young Infants

This study compared 3- to 4-month-olds' recognition of previously unfamiliar faces learned in a moving or a static condition. Infants in the moving condition showed successful recognition with only 30 s familiarization, even when different images of a face were used in the familiarization and test phase (Experiment 1). In contrast, infants in the static condition showed successful recognition only when the familiarization duration was lengthened to 90 s and when the same image was used between the familiarization and test phase (Experiments 2 and 3). Furthermore, presentation of multiple static images of a face did not yield the same level of performance as the moving condition (Experiment 4). These results suggest that facial motion promotes young infants' recognition of unfamiliar faces.     

Do the eyes have it? Inferring mental states from animated faces in autism

The ability of individuals with autistic spectrum disorders (ASD) to infer mental states from dynamic and static facial stimuli was investigated. In Experiment 1, individuals with ASD (10- to 14-year olds; N=18) performed above chance but not as well as controls. Accuracy scores for mental states did not differ between dynamic and static faces. Furthermore, participants with ASD gained higher scores when the eyes conveyed information than when this region remained static and neutral. Experiment 2 revealed that those with ASD (11- to 15-year olds; N=18) were as successful as controls in recognizing mental states when the eyes were presented in isolation or in the context of the whole face. Findings challenge claims that individuals with ASD are impaired at inferring mental states from the eyes.     

Do infants see emotional expressions in static faces?

To determine whether young infants discriminate photographs of different emotions on an affect-relevant basis or on the basis of isolated features unrelated to emotion, groups of 17-, 23-, and 29-week-olds were habituated to slides of 8 women posing either Toothy Angry, Nontoothy Angry, or Nontoothy Smiling facial expressions and were then shown 2 new women in the familiarized expression and in a novel Toothy Smiling expression. At all 3 ages, recovery to the novel Toothy Smiling faces occurred only after habituation to Nontoothy faces (whether smiling or angry), not after habituation to Toothy Angry faces, indicating that infants had been responsive to nonspecific features of the photographs (presence or absence of bared teeth) rather than to affectively relevant configurations of features. In a second experiment, 2 older age groups (35 and 41 weeks) also proved to be insensitive to affect-related aspects of still faces, though more so for angry than for happy expressions. It is suggested that the young infant's difficulty in extracting emotional information from static stimuli may be attributable to the absence of the critical invariants (dynamic, multimodally specified) that characterize naturalistic expressions of emotion.     

Confusions between memories for performed and imagined actions: a developmental comparison

Children are often assumed to be more confused than adults are about the origin of self-generated memories (e.g., what they did or thought). The present experiments showed evidence in support of this assumption but only under some circumstances. In Experiment 1, 6- and 9-year-olds were as good as adults in distinguishing what they did from what they saw someone else do. However, children had particular trouble distinguishing what they did from what they imagined doing. Confusion between performed and imagined actions was evident across a range of actions. Clustering data also showed that information about origin is part of the memory for an event; all subjects recalled actions according to who performed what action (Experiment 1). Further, the presence of person categories as a basis for organization reduced clustering based on action class more for children than for adults (Experiment 1 vs. 2). Collectively, these findings indicate that children become sensitive to some distinctions in memories sooner than they do to others.     

Find Your Manners: How Do Infants Detect the Invariant Manner of Motion in Dynamic Events?

To learn motion verbs, infants must be sensitive to the specific event features lexicalized in their language. One event feature important for the acquisition of English motion verbs is the manner of motion. This article examines when and how infants detect manners of motion across variations in the figure's path. Experiment 1 shows that 13- to 15-month-olds (N = 30) can detect an invariant manner of motion when the figure's path changes. Experiment 2 reveals that reducing the complexity of the events, by dampening the figure's path, helps 10- to 12-month-olds (N = 19) detect the invariant manner. These findings suggest that: (a) infants notice event features lexicalized in English motion verbs, and (b) attention to manner can be promoted by reducing event complexity.     

Role of proactive interference in infantile forgetting

Ontogenetic changes in the role of proactive interference in augmenting forgetting were tested with 444 rats as subjects. In Experiment 1, Phase 1 (the source of proactive interference) included events that were contingent or not contingent on responding in the context of either the Phase 2 training apparatus or a distinctly different apparatus. After learning a spatial discrimination for Phase 2, retention tests were given after intervals of 2 min, 1 day, 7 days, 30 days, or 65 days. The results indicated: (1) infantile amnesia, and (2) proactive interference for infant rats but not for adults, in spite of substantial simple forgetting among adults. Experiment 2 extended the test to a go/no-go avoidance task. The results of Experiment 2 gave some indication that infants were more susceptible than were adults to proactive interference over short intervals, but the generality of this relationship was sufficiently ambiguous as to suggest different mechanisms of interference for the discrimination and go/no-go tasks. These data indicate multiple mechanisms of infantile forgetting that may vary with certain characteristics of the task.     

Emotional eavesdropping: infants selectively respond to indirect emotional signals

Two experiments examined whether 18-month-olds learn from emotions directed to a third party. Infants watched an adult perform actions on objects, and an Emoter expressed Anger or Neutral affect toward the adult in response to her actions. The Emoter then became neutral and infants were given access to the objects. Infants' actions were influenced by their memory of the Emoter's affect. Moreover, infants' actions varied as a function of whether they were currently in the Emoter's visual field. If the previously angry Emoter was absent (Experiment 1) or turned her back (Experiment 2), infants did not use the prior emotion to regulate their behavior. Infants learn from emotional eavesdropping, and their subsequent behavior depends on the Emoter's orientation toward them.     

Connecting the Dots Between Past and Future: Constraints in Episodic Future Thinking in Early Childhood

Preschoolers have limited capacity to use past experiences to prepare for the future. Two experiments sought to further understand these limitations. Experiment 1 (N = 42) showed that 3- to 4-year olds’ difficulty performing anticipated future actions was constrained by their memory for relevant past actions, especially those including temporal information. Experiment 2 (N = 94) sought to determine whether preschoolers fail to see that past experiences can inform future-oriented actions. When the connection between the past and future was experimentally heightened, future thinking accuracy improved, but only if preschoolers remembered past experiences. The results indicate that past recall is a prerequisite for future thinking but failure to bridge past and future further accounts for observed limitations in future thinking in early childhood.     

Increasing Steps in Recall of Events: Factors Facilitating Immediate and Long-Term Memory in 13.5- and 16.5-Month-Old Children

Children late in the second year of life show patterns of event recall similar to those of older children: (a) well-ordered immediate and delayed recall, and (b) facilitation of recall by familiarity and by enabling relations. We used elicited imitation to test whether the patterns extend to children early in the second year. In Experiment 1, 13.5- and 16.5-month-olds accurately recalled familiar and novel 2-act sequences immediately and after a 1-week delay. For 16.5-month-olds, recall was facilitated by familiarity and by enabling relations; for 13.5-month-olds, only enabling relations facilitated recall. In Experiment 2, verbal cues were used to test immediate and 1-week delayed recall of 3-act sequences. For both ages, recall was facilitated by familiarity and by enabling relations. Experiment 3 verified that the verbal information served to cue recall of previously experienced events, not to "suggest" sequences that could be performed. Together the results demonstrate that children as young as 13 months can recall specific events after a delay. They also suggest development in sensitivity to factors that facilitate recall.     

Proactive interference in the retention of “attentional sets” in pigeons

In Experiment 1, six groups of pigeons (n=8) were tested for wavelength generalization either immediately or 24 h after learning a successive discrimination, with 550 nm reinforced and a black vertical line extinguished. The groups differed in the stimulus present during single stimulus pretraining, which was 550 nm (pretrain S+), the vertical Une (pretrain S?), or a neutral dim white light (pretrain Sn), respectively. The three immediate generalization gradients were steep and indistinguishable, reflecting only the immediately preceding discrimination training condition. The three delay gradients were flatter, with the flattening particularly marked in the pretrain S? group. This was interpreted as proactive interference (PI) resulting from the memory that both the 550-nm and the line stimuli had previously been reinforced. In Experiment 2, two (TD) groups of pigeons (n=16) were given single stimulus training with a 555-nm keylight followed by eight sessions of discrimination training with two line angles, then one session of non-differential (ND) training with the same two lines, and then a wavelength generalization test either immediately or after a 24-h delay. Two other (hold) groups (n=16) received similar training, except for the TD Une angle training sessions, in these hold groups, the wavelength gradient was flatter in a delayed test; in the TD groups it was steeper, indicating PI from the prior TD training. These two experiments suggest that the “attentional sets,” which purportedly result from TD and ND training, may fruitfully be viewed as target memories subject to the principles of interference theory.