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

Social cues at encoding affect memory in 4-month-old infants

Available evidence suggests that infants use adults' social cues for learning by the second half of the first year of life. However, little is known about the short-term or long-term effects of joint attention interactions on learning and memory in younger infants. In the present study, 4-month-old infants were familiarized with visually presented objects in either of two conditions that differed in the degree of joint attention (high vs. low). Brain activity in response to familiar and novel objects was assessed immediately after the familiarization phase (immediate recognition), and following a 1-week delay (delayed recognition). The latency of the Nc component differentiated between recognition of old versus new objects. Pb amplitude and latency were affected by joint attention in delayed recognition. Moreover, the frequency of infant gaze to the experimenter during familiarization differed between the two experimental groups and modulated the Pb response. Results show that joint attention affects the mechanisms of long-term retention in 4-month-old infants. We conclude that joint attention helps children at this young age to recognize the relevance of learned items.

Recognition of faces and Greebles in 3-month-old infants: Influence of temperament and cognitive abilities

The aim of the present study was to investigate whether temperament and cognitive abilities are related to recognition performance of Caucasian and African faces and of a nonfacial stimulus class, Greebles. Seventy Caucasian infants were tested at 3 months with a habituation/dishabituation paradigm and their temperament and cognitive abilities were measured. Analyses revealed that only infants with easy temperament recognized familiar Greebles from the habituation phase. A similar pattern was found for cognitive abilities showing that only infants with higher cognitive abilities recognized Greebles. Irrespectively of temperament and cognitive abilities, all infants recognized the faces. Thus, the data suggest that recognition of unfamiliar Greebles, but not of faces, is demanding for 3-month-old infants with difficult temperament or lower cognitive abilities.

Neural correlates of visual recognition in 3-month-old infants: the role of experience

Early experiences contribute powerfully to the development of neural systems that underlie various perceptual and cognitive abilities in humans. In one of the first studies to systematically control infants' exposure to a familiar object, we examined the effects of controlled experience on the neural correlates of visual recognition in two groups of infants. One group received 1 month of in-home familiarization to a 3D model of a female face. Another group received 1.5 min of in-lab familiarization to the 3D model of a female face, creating two conditions that differed in the amount and, importantly, the context of exposure to a familiar stimulus. Following familiarization, event-related potentials (ERPs) were recorded at 3 months of age while infants viewed pictures of the familiar face and an unfamiliar face. Results demonstrated that while both groups of infants discriminated between the familiar and unfamiliar faces, the pattern of neural processing was reversed for the two groups. Thus, the amount and context of visual exposure altered the neural correlates of recognition processes in young infants.

Faktoren der Gesichtserkennung im ersten Lebensjahr

Zusammenfassung. Schon gleich nach der Geburt bevorzugen es Säuglinge, Gesichter gegenüber anderen visuellen Objekten anzuschauen und lernen dann im Laufe des ersten Lebensjahres, immer mehr Gesichter zu unterscheiden und wiederzuerkennen. Es wird derzeit noch diskutiert, welche Faktoren für diese zunehmende Unterscheidungsleistung von Gesichtern verantwortlich sind. Ziel des vorliegenden Beitrags ist es darzulegen, welche Rolle die Faktoren – emotionaler Ausdruck von Gesichtern, Temperament und Kognition der Säuglinge sowie die Kultur – für eine solche Unterscheidungsleistung von Gesichtern innerhalb des ersten Lebensjahres spielen.

Entwicklung des Gedächtnisses bei Säuglingen und Kleinkindern

Zusammenfassung. In diesem Forschungsüberblick geht es um die Ontogenese des impliziten und expliziten Gedächtnisses im Säuglings- und Kleinkindalter. Die meisten Säuglingsforscher kommen dabei zu dem Ergebnis, dass das implizite Gedächtnis in den ersten Lebenswochen, wenn nicht sogar in den ersten Lebenstagen, seine Arbeit aufnimmt, während explizite Gedächtnisleistungen erst in der zweiten Hälfte des ersten Lebensjahres nachweisbar sind. Es gibt zudem eine Reihe von Überlegungen, wonach die expliziten Gedächtnisleistungen zunächst allgemeines Wissen widerspiegeln, so dass es sich um Leistungen des semantischen Gedächtnisses handelt. Episodische Gedächtnisleistungen nach Tulving (2001) , also das Erinnern eigenen, vergangenen Erlebens (mentale Zeitreise) sind an die Entwicklung einer Reihe von Bedingungen geknüpft (z.B. Selbstentwicklung, Entwicklung multipler Repräsentationen). Aufgrund dieser Voraussetzungen wird episodisches Gedächtnis erst gegen Ende des zweiten Lebensjahrs möglich.

Age-related changes in visual recognition memory during infancy and early childhood

Age-related changes in long-term memory during infancy and early childhood were examined using the Visual Recognition Memory (VRM) procedure. Independent groups of 1-, 2-, 3-, and 4-year-olds were familiarized with a visual stimulus and were tested either immediately or after a delay that ranged from 24 hr to 6 months. Although all age groups exhibited a significant novelty preference when tested immediately after familiarization, clear age-related differences emerged over longer retention intervals. We conclude that age-related increases in basic retention are a fundamental aspect of mammalian memory development and, in humans, these increases may play a vital role in the offset of childhood amnesia.

Face recognition across varying poses in 7- and 9-month-old infants: The role of facial expression

Three studies were conducted to determine whether 7- and 9-month-old infants generalize face identity to a novel pose of the same face when only internal face sections with and without an emotional expression were presented. In Study 1, 7- and 9-month-old infants were habituated to a full frontal or three-quarter pose of a face with neutral facial expression. In Study 2, 7-month-olds were habituated to a face with a positive or negative expression. In the novelty preference test, immediately following habituation, infants were shown a pair of faces: the habituation face in a novel pose and a novel face in the same pose. Generalization of facial identity was inferred from longer fixation time to the novel face. Whereas 7-month-old infants did not dishabituate to the novel face with neutral expression, 9-month-olds fixated longer on the novel face with neutral expression (Study 1). However, when faces displayed a positive or negative expression 7-month-olds also looked longer at the novel face, indicating generalization of the habituation face to a novel pose (Study 2). Study 3 showed that 7-montholds’ generalization ability in Study 2 cannot be explained by an inability to discriminate between the two poses of the habituation face. Results showed 9- but not 7-month-olds recognized neutral looking faces in a novel pose, and 7-month-olds’ face recognition ability was enhanced by emotional facial expression.

Newborn infants learn during sleep

Newborn infants must rapidly adjust their physiology and behavior to the specific demands of the novel postnatal environment. This adaptation depends, at least in part, on the infant's ability to learn from experiences. We report here that infants exhibit learning even while asleep. Bioelectrical activity from face and scalp electrodes was recorded from neonates during an eye movement conditioning procedure in which a tone was followed by a puff of air to the eye. Sleeping newborns rapidly learned the predictive relationship between the tone and the puff. Additionally, in the latter part of training, these infants exhibited a frontally maximum positive EEG slow wave possibly reflecting memory updating. As newborns spend most of their time sleeping, the ability to learn about external stimuli in the postnatal environment during nonawake states may be crucial for rapid adaptation and infant survival. Furthermore, because eyelid conditioning reflects functional cerebellar circuitry, this method potentially offers a unique approach for early identification of infants at risk for a range of developmental disorders including autism and dyslexia.

Toddlers with elevated autism symptoms show slowed habituation to faces

We explored social information processing and its relation to social and communicative symptoms in toddlers with Autism Spectrum Disorder (ASD) and their siblings. Toddlers with more severe symptoms of autism showed slower habituation to faces than comparison groups; slower face learning correlated with poorer social skills and lower verbal ability. Unaffected toddlers who were siblings of children with ASD also showed slower habituation to faces compared with toddlers without siblings with ASD. We conclude that slower rates of face learning may be an endophenotype of ASD and is associated with more severe symptoms among affected individuals.

Two are better than one: comparison influences infants' visual recognition memory

Despite a large literature on infants' memory for visually presented stimuli, the processes underlying visual memory are not well understood. Two studies with 4-month-olds (N=60) examined the effects of providing opportunities for comparison of items on infants' memory for those items. Experiment 1 revealed that 4-month-olds failed to show evidence of memory for an item presented during familiarization in a standard task (i.e., when only one item was presented during familiarization). In Experiment 2, infants showed robust memory for one of two different items presented during familiarization. Thus, infants' memory for the distinctive features of individual items was enhanced when they could compare items.

When do infants differentiate profile face from frontal face? A near-infrared spectroscopic study

The objective of the present study was to determine whether a developmental difference occurs in brain activity when infants look at frontal and profile views using near-infrared spectroscopy (NIRS), which is an optical imaging technique used to measure changes in the concentrations of oxyhemoglobin (oxy-Hb), deoxyhemoglobin (deoxy-Hb), and total hemoglobin (total-Hb). For this objective, we compared NIRS results in two age groups, 5- and 8-month-old infants, while they were looking at frontal views, profile views, and objects. We found that the concentration of oxy-Hb and total-Hb in the 5-month-old group increased for only frontal views in the right temporal regions. In contrast, the concentration of oxy-Hb and total-Hb in the 8-month-old group increased for both frontal and profile views in the right temporal regions. Therefore, the present study indicated that the right hemisphere was dominant for the perception of profile views as well as frontal views. In addition, the most important and interesting finding was that the infants' brain activity of the face area would become view-invariant at the age of 8 months but not at 5 months. The developmental period for view-invariant face recognition has been discussed in previous psychological studies, but this is the first objective study to confirm that the period is between 5- and 8-months by measuring the blood flow in the brain using NIRS.

Development of infants' attention to faces during the first year

In simple tests of preference, infants as young as newborns prefer faces and face-like stimuli over distractors. Little is known, however, about the development of attention to faces in complex scenes. We recorded eye-movements of 3-, 6-, and 9-month-old infants and adults during free-viewing of clips from A Charlie Brown Christmas (an animated film). The tendency to look at faces increased with age. Using novel computational tools, we found that 3-month-olds were less consistent (across individuals) in where they looked than were older infants. Moreover, younger infants' fixations were best predicted by low-level image salience, rather than the locations of faces. Between 3 and 9 months of age, infants gradually focused their attention on faces. We discuss several possible interpretations of this shift in terms of social development, cross-modal integration, and attentional/executive control.

Facial experience during the first year

Parents of 2-, 5-, 8-, and 11-month-olds used two scales we developed to provide information about their infants' facial experience with familiar and unfamiliar individuals during one week. Results showed large discrepancies in the race, sex, and age of faces that infants experience during their first year with the majority of their facial experience being with their primary caregiver, females, and other individuals of the same-race and age as their primary caregiver. The infant's age and an unfamiliar individual's sex were predictive of their time spent interacting with one another. Moreover, an unfamiliar individual's sex was predictive of the attention infants allocated during social interactions. Differences in frequency and length of interactions with certain types of faces, as well as in infant attention toward certain individuals, all likely contribute to the development of expertise in processing commonly experienced face types and deficiencies in processing less commonly experienced face types.

Newborns’ face recognition over changes in viewpoint

The study investigated the origins of the ability to recognize faces despite rotations in depth. Four experiments are reported that tested, using the habituation technique, whether 1-to-3-day-old infants are able to recognize the invariant aspects of a face over changes in viewpoint. Newborns failed to recognize facial perceptual invariances between profile and full-face poses (Experiment 1), and profile and 3/4 poses (Experiment 3). Conversely, newborns recognized the identity of a face through full-face and 3/4 poses (Experiment 2). This result cannot be explained as a consequence of newborns' inability to discriminate between the full-face and 3/4 points of view (Experiment 4). Overall, evidence was provided that newborns are able to derive a representation of an unfamiliar face that is resilient to a certain degree of rotation in depth, from full-face to 3/4 and vice versa.

The other-race effect develops during infancy: evidence of perceptual narrowing

Experience plays a crucial role in the development of face processing. In the study reported here, we investigated how faces observed within the visual environment affect the development of the face-processing system during the 1st year of life. We assessed 3-, 6-, and 9-month-old Caucasian infants' ability to discriminate faces within their own racial group and within three other-race groups (African, Middle Eastern, and Chinese). The 3-month-old infants demonstrated recognition in all conditions, the 6-month-old infants were able to recognize Caucasian and Chinese faces only, and the 9-month-old infants' recognition was restricted to own-race faces. The pattern of preferences indicates that the other-race effect is emerging by 6 months of age and is present at 9 months of age. The findings suggest that facial input from the infant's visual environment is crucial for shaping the face-processing system early in infancy, resulting in differential recognition accuracy for faces of different races in adulthood.

Accounting for change in declarative memory: A cognitive neuroscience perspective

The medial temporal lobe memory system matures relatively early and supports rudimentary declarative memory in young infants. There is considerable development, however, in the memory processes that underlie declarative memory performance during infancy. Here we consider age-related changes in encoding, retention, and retrieval in the context of current knowledge about the brain systems that may underlie these memory processes. While changes in infants' encoding may be attributed to rapid myelination during the first year of life, improvements in long-term retention and flexible retrieval are likely due to the prolonged development of the dentate gyrus. Future studies combining measures of brain and behavior are critical in improving our understanding of how brain development drives memory development during infancy and early childhood.

Evidence of a shift from featural to configural face processing in infancy

Two experiments examined whether 4-, 6-, and 10-month-old infants process natural looking faces by feature, i.e. processing internal facial features independently of the facial context or holistically by processing the features in conjunction with the facial context. Infants were habituated to two faces and looking time was measured. After habituation they were tested with a habituation face, a switch-face, or a novel face. In the switch-faces, the eyes and mouth of the habituation faces were switched. The results showed that the 4-month-olds processed eyes and mouth by feature, whereas the 10-month-olds processed both features holistically. The 6-month-olds were in a transitional stage where they processed the mouth holistically but the eyes still as a feature. Thus, the results demonstrated a shift from featural to holistic processing in the age range of 4 to 10 months.

Electrophysiological Evaluation of Human Brain Development

The complex development of the human brain during infancy can only be understood by convergent structural, functional, and behavioral measurements. The evaluation of event-related potentials (ERPs) is the most effective current way to look at infant brain function. ERP paradigms can be used to examine the simple transmission of sensory information to the cortex and the discrimination of this information within the cortex. The main developmental changes involve localization of function as the brain becomes tuned to the experienced world (related to synaptic pruning) and a speeding up of transmission as pathways become efficient (related to myelination). ERPs that occur in relation to different temporal aspects of a stimulus (onset-responses, offset-responses, sustained potentials and steady-state responses) and ERPs recorded at different stimulus rates may help track perceptual development from a temporal perspective. Particularly important in human development are the ERP changes that occur in the processing of speech sounds and human faces. At present, ERP studies can show differences between groups of subjects that can demonstrate developmental disorders or elucidate mechanisms of development. However, because of their variability, ERPs are less helpful in determining whether an individual infant is developing abnormally. Where possible, ERP measurements should be used in conjunction with behavioral tests so as to relate performance to mechanism, and with anatomical brain measurements to relate mechanism to structure.

Behavioural and neurophysiological evidence for face identity and face emotion processing in animals

Visual cues from faces provide important social information relating to individual identity, sexual attraction and emotional state. Behavioural and neurophysiological studies on both monkeys and sheep have shown that specialized skills and neural systems for processing these complex cues to guide behaviour have evolved in a number of mammals and are not present exclusively in humans. Indeed, there are remarkable similarities in the ways that faces are processed by the brain in humans and other mammalian species. While human studies with brain imaging and gross neurophysiological recording approaches have revealed global aspects of the face-processing network, they cannot investigate how information is encoded by specific neural networks. Single neuron electrophysiological recording approaches in both monkeys and sheep have, however, provided some insights into the neural encoding principles involved and, particularly, the presence of a remarkable degree of high-level encoding even at the level of a specific face. Recent developments that allow simultaneous recordings to be made from many hundreds of individual neurons are also beginning to reveal evidence for global aspects of a population-based code. This review will summarize what we have learned so far from these animal-based studies about the way the mammalian brain processes the faces and the emotions they can communicate, as well as associated capacities such as how identity and emotion cues are dissociated and how face imagery might be generated. It will also try to highlight what questions and advances in knowledge still challenge us in order to provide a complete understanding of just how brain networks perform this complex and important social recognition task.

Holistic face processing is mature at 4 years of age: Evidence from the composite face effect

Although it is acknowledged that adults integrate features into a representation of the whole face, there is still some disagreement about the onset and developmental course of holistic face processing. We tested adults and children from 4 to 6 years of age with the same paradigm measuring holistic face processing through an adaptation of the composite face effect [Young, A. W., Hellawell, D., & Hay, D. C. (1987). Configurational information in face perception. Perception, 16, 747-759]. In Experiment 1, only 6-year-old children and adults tended to perceive the two identical top parts as different, suggesting that holistic face processing emerged at 6 years of age. However, Experiment 2 suggested that these results could be due to a response bias in children that was cancelled out by always presenting two faces in the same format on each trial. In this condition, all age groups present strong composite face effects, suggesting that holistic face processing is mature as early as after 4 years of experience with faces.

Human memory development and its dysfunction after early hippocampal injury

Cognitive memory involves long-term memories for facts (semantic memory) and personal experiences (episodic memory) that can be brought to mind. There is consensus that the hippocampus and related medial temporal lobe (MTL) structures are crucial for adult cognitive memory, but much less is known about their contribution to memory during infancy and childhood. We argue that the MTL is involved in memory from early in life, supporting recognition memory within the first postnatal months and recall memory within the first year. We propose that normal development involves a sequence in which a form of semantic-like memory emerges first, whereas the characteristics of episodic memory develop only later with progressive development of the hippocampus. Early bilateral injury to the hippocampus disrupts this normal pattern such that memory skills cannot develop beyond the stage of semantic memories. This review is part of the INMED/TINS special issue "Nature and nurture in brain development and neurological disorders", based on presentations at the annual INMED/TINS symposium (http://inmednet.com/).

Childhood trauma and personality disorder: toward a biological model

Cross-sectional and prospective associations of personality disorder with childhood trauma provide an important clue regarding the biological mechanism of personality disorder. In this review, empirical literature from several domains is summarized. These include relevant findings from behavioral genetics, preclinical models of early life parental care, and clinical translational studies of personality disorder. Identification of the biological mechanism by which childhood trauma exerts an effect on personality disorder may require modification of the conceptualization of personality disorder, either as a set of categories or dimensions.

The Development of Infant Learning About Specific Face-Voice Relations

This study examined the development of infants' ability to perceive, learn, and remember the unique face-voice relations of unfamiliar adults. Infants of 2, 4, and 6 months were habituated to the faces and voices of 2 same-gender adults speaking and then received test trials where the faces and voices were synchronized yet mismatched. Results indicated that 4- and 6-month-olds, but not 2-month-olds, detected the change in face-voice pairings. Two-month-olds did, however, discriminate among the faces and voices in a control study. Results of a subsequent intermodal matching procedure indicated that only the 6-month-olds showed matching and memory for the face-voice relations. These findings suggest that infants' ability to detect the arbitrary relations between specific faces and voices of unfamiliar adults emerges between 2 and 4 months of age, whereas matching and memory for these relations emerges somewhat later, perhaps between 4 and 6 months of age.

Recognition of own-race and other-race faces by three-month-old infants

BACKGROUND

People are better at recognizing faces of their own race than faces of another race. Such race specificity may be due to differential expertise in the two races.

METHOD

In order to find out whether this other-race effect develops as early as face-recognition skills or whether it is a long-term effect of acquired expertise, we tested face recognition in 3-month-old Caucasian infants by conducting two experiments using Caucasian and Asiatic faces and a visual pair-comparison task. We hypothesized that if the other race effect develops together with face processing skills during the first months of life, the ability to recognize own-race faces will be greater than the ability to recognize other-race faces: 3-month-old Caucasian infants should be better at recognizing Caucasian faces than Asiatic faces. If, on the contrary, the other-race effect is the long-term result of acquired expertise, no difference between recognizing own- and other-race faces will be observed at that age.

RESULTS

In Experiment 1, Caucasian infants were habituated to a single face. Recognition was assessed by a novelty preference paradigm. The infants' recognition performance was better for Caucasian than for Asiatic faces. In Experiment 2, Caucasian infants were familiarized with three individual faces. Recognition was demonstrated with both Caucasian and Asiatic faces.

CONCLUSIONS

These results suggest that (i) the representation of face information by 3-month-olds may be race-experience-dependent (Experiment 1), and (ii) short-term familiarization with exemplars of another race group is sufficient to reduce the other-race effect and to extend the power of face processing (Experiment 2).

Development of face-sensitive event-related potentials during infancy: a review

Event-related potential (ERP) studies in adults have identified a number of components related to encoding and recognition memory of faces. Although behavioural studies indicate that even very young infants are able to detect faces and recognise familiar individuals, very few ERP studies document the neural correlates of these early abilities. In this article, we review four components (P1, N290, P400, Nc) and slow wave activity that are elicited while infants view faces. Where possible we draw links between these components and their possible equivalents to those observed in children and adults, and we highlight areas where further investigation is required. The theoretical importance of ERP studies of face processing in infants for debates about the origins and domain specificity of the adult cortical face processing system are discussed.

Developmental changes in face processing skills

Expertise in processing differences among faces in the spacing among facial features (second-order relations) is slower to develop than expertise in processing the shape of individual features or the shape of the external contour. To determine the impact of the slow development of sensitivity to second-order relations on various face-processing skills, we developed five computerized tasks that require matching faces on the basis of identity (with changed facial expression or head orientation), facial expression, gaze direction, and sound being spoken. In Experiment 1, we evaluated the influence of second-order relations on performance on each task by presenting them to adults (N=48) who viewed the faces either upright or inverted. Previous studies have shown that inversion has a larger effect on tasks that require processing the spacing among features than it does on tasks that can be solved by processing the shape of individual features. Adults showed an inversion effect for only one task: matching facial identity when there was a change in head orientation. In Experiment 2, we administered the same tasks to children aged 6, 8, and 10 years (N=72). Compared to adults, 6-year-olds made more errors on every task and 8-year-olds made more errors on three of the five tasks: matching direction of gaze and the two facial identity tasks. Ten-year-olds made more errors than adults on only one task: matching facial identity when there was a change in head orientation (e.g., from frontal to tilted up). Together, the results indicate that the slow development of sensitivity to second-order relations causes children to be especially poor at recognizing the identity of a face when it is seen in a new orientation.

Innate visual object recognition in vertebrates: some proposed pathways and mechanisms

Almost all vertebrates are capable of recognizing biologically relevant stimuli at or shortly after birth, and in some phylogenetically ancient species visual object recognition is exclusively innate. Extensive and detailed studies of the anuran visual system have resulted in the determination of the neural structures and pathways involved in innate prey and predator recognition in these species [Behav. Brain Sci. 10 (1987) 337; Comp. Biochem. Physiol. A 128 (2001) 417]. The structures involved include the optic tectum, pretectal nuclei and an area within the mesencephalic tegmentum. Here we investigate the structures and pathways involved in innate stimulus recognition in avian, rodent and primate species. We discuss innate stimulus preferences in maternal imprinting in chicks and argue that these preferences are due to innate visual recognition of conspecifics, entirely mediated by subtelencephalic structures. In rodent species, brainstem structures largely homologous to the components of the anuran subcortical visual system mediate innate visual object recognition. The primary components of the mammalian subcortical visual system are the superior colliculus, nucleus of the optic tract, anterior and posterior pretectal nuclei, nucleus of the posterior commissure, and an area within the mesopontine reticular formation that includes parts of the cuneiform, subcuneiform and pedunculopontine nuclei. We argue that in rodent species the innate sensory recognition systems function throughout ontogeny, acting in parallel with cortical sensory and recognition systems. In primates the structures involved in innate stimulus recognition are essentially the same as those in rodents, but overt innate recognition is only present in very early ontogeny, and after a transition period gives way to learned object recognition mediated by cortical structures. After the transition period, primate subcortical sensory systems still function to provide implicit innate stimulus recognition, and this recognition can still generate orienting, neuroendocrine and emotional responses to biologically relevant stimuli.

Gesichterverarbeitung im Kleinkind- und Vorschulalter

Zusammenfassung. Während für die allgemeine visuelle Wahrnehmung im Kleinkind- und Vorschulalter eine holistische Verarbeitung postuliert wird, wird bei Kindern für die Verarbeitung von Gesichtern eine analytische Verarbeitungsform angenommen. Allerdings sind Studien zur Art der Gesichterverarbeitung bisher ausschließlich ab dem Schulalter durchgeführt worden. Deshalb war Ziel der vorliegenden Experimente, die Gesichterverarbeitung im Kleinkind- und Vorschulalter zu untersuchen und zu prüfen, inwieweit die Annahme einer holistischen Verarbeitung auf die Gesichterverarbeitung übertragen werden kann. Im Rahmen altersspezifischer Versionen einer Kategorienlernaufgabe wurde in zwei Experimenten untersucht, ob Klein- und Vorschulkinder (3- und 4jährige (N = 73) in Experiment 1 und 5- bis 7jährige (N = 48) in Experiment 2) auf analytische Weise (durch Fokussierung auf einzelne Gesichtsmerkmale) oder holistische Weise (durch Orientierung an der Gesamtähnlichkeit der Gesichter) lernen, vierdimensional variierte Schemagesichter zu kategorisieren. Die Ergebnisse zeigten, daß bei Kindern zwischen 3 und 7 Jahren eindeutig die analytische Verarbeitung gegenüber der holistischen dominierte. Altersunterschiede verdeutlichten sich darin, wie konsistent die Fokussierungen auf einzelne Merkmale vorgenommen wurden und welche Gesichtsmerkmale der Analyse dienten. Die für die allgemeine visuelle Wahrnehmung angenommene holistische Verarbeitung gilt somit nicht für die Verarbeitung von Gesichtern. Stattdessen beginnt die bislang im Schulalter beobachtete analytische Gesichterverarbeitung bereits im Kleinkindalter.

Neonatal aspiration lesions of the hippocampal formation impair visual recognition memory when assessed by paired-comparison task but not by delayed nonmatching-to-sample task

Previous experiments showed that neonatal aspiration lesions of the hippocampal formation in monkeys yield no visual recognition loss at delays up to 10 min, when recognition memory was assessed by a trial-unique delayed nonmatching-to-sample (DNMS) task. The present study examined whether neonatal hippocampal lesions also have no effect on visual recognition when assessed by a visual paired-comparison (VPC) task. In the VPC task, animals are looking at visual stimuli and their preference for viewing new stimuli is measured. Normal adult monkeys showed strong preference for looking at the novel stimuli at all delays tested. By contrast, adult monkeys with neonatal hippocampal lesions, which included the dentate gyrus, cornus ammon (CA) fields, subicular complex, and portions of parahippocampal areas TH/TF, showed preference for novelty at short delays of 10 s but not at longer delays of 30 s to 24 h. This visual recognition loss contrasts with the normal performance of the same operated animals when tested in the DNMS task. The discrepancy between the results obtained in the two recognition tasks suggests that, to perform normally on the DNMS task, the operated monkeys may have used behavioral strategies that do not depend on the integrity of the hippocampal formation. In this respect, VPC appears to be a more sensitive task than DNMS to detect damage to the hippocampal region in primates.