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Recent studies have shown that infants' face recognition rests on a robust face representation that is resilient to a variety of facial transformations such as rotations in depth, motion, occlusion or deprivation of inner/outer features. Here, we investigated whether 3-month-old infants' ability to represent the invariant aspects of a face is affected by the presence of an external add-on element, i.e. a hat. Using a visual habituation task, three experiments were carried out in which face recognition was investigated by manipulating the presence/absence of a hat during face encoding (i.e. habituation phase) and face recognition (i.e. test phase). An eye-tracker system was used to record the time infants spent looking at face-relevant information compared to the hat. The results showed that infants' face recognition was not affected by the presence of the external element when the type of the hat did not vary between the habituation and test phases, and when both the novel and the familiar face wore the same hat during the test phase (Experiment 1). Infants' ability to recognize the invariant aspects of a face was preserved also when the hat was absent in the habituation phase and the same hat was shown only during the test phase (Experiment 2). Conversely, when the novel face identity competed with a novel hat, the hat triggered the infants' attention, interfering with the recognition process and preventing the infants' preference for the novel face during the test phase (Experiment 3). Findings from the current study shed light on how faces and objects are processed when they are simultaneously presented in the same visual scene, contributing to an understanding of how infants respond to the multiple and composite information available in their surrounding environment.

Many studies have shown that newborns prefer (e.g. Goren, Sarty & Wu, 1975; Valenza, Simion, Macchi Cassia & Umiltà, 1996) and recognize (e.g. Bushnell, Say & Mullin, 1989; Pascalis & de Schonen, 1994) faces. However, it is not known whether, at birth, faces are still preferred and recognized when some of their parts are not visible because hindered by other configurations, that is when faces are partly occluded. Also, it is not known whether newborns' preference for an upright over an inverted face and newborns' face recognition are differentially affected depending on the salience of the occluded face features. Seventy-seven newborns (mean age of 43.5 hrs) were tested using the preferential looking (Experiment 1) and the habituation techniques (Experiment 2). Results demonstrated that newborns prefer and recognize occluded faces even if some portions of them are not available, at least when the hindered features are not salient. On the contrary, these abilities are affected by obscuring high salience facial features (i.e. eyes). However, while in the case of face detection, eyes occlusion completely prevented newborns' face detection, in the case of face recognition an analogous stimulus manipulation heavily impaired, but did not totally preclude, newborns' recognition performance. The data collected improve our comprehension of newborns' way of processing and encoding information to detect and recognize faces.

The present chapter deals with the topic of the ontogeny and development of face processing in the first months of life and is organized into two sections concerning face detection and face recognition. The first section focuses on the mechanisms underlying infants' visual preference for faces. Evidence is reviewed supporting the contention that newborns' face preferences is due to a set of non-specific constraints that stem from the general characteristics of the human visuo-perceptual system, rather than to a representational bias for faces. It is shown that infants' response to faces becomes more and more tuned to the face category over the first 3 months of life, revealing a gradual progressive specialization of the face-processing system. The second section sought to determine the properties of face recognition at birth. In particular, a series of experiments are presented to examine whether the inner facial part is processed and encoded when newborns recognize a face, and what kind of information--featural or configural--newborns' face recognition rely on. Overall, results are consistent with the existence of general constraints present at birth that tune the system to become specialized for faces later during development.

This study was aimed at investigating the face preference phenomenon and its underlying mechanisms at 3 months of age. Using an eye-tracker apparatus, Experiment 1 demonstrated that 3-month-olds prefer natural face images to unnatural ones, replicating and extending previous evidence obtained with schematic facelike stimuli. Experiments 2 and 3 showed that the general mechanisms that induce face preference in newborns could not explain the same phenomenon at 3 months of age, when infants are attracted by perceptual cues more specific to faces. This suggests that signs of a process of cognitive specialization are already present in 3-month-olds' visual behavior toward faces.

It has been proposed that newborns' preferential orienting to faces is primarily controlled by a subcortical mechanism. As an index of subcortical, extrageniculate mediation, the asymmetry between the temporal and nasal hemifields was exploited. In Experiment 1, under monocular viewing conditions, newborns were presented with a pattern that had 3 blobs in the appropriate locations for the eyes and the mouth or a pattern that had an inverted position of the blobs. Results showed that newborns preferentially oriented to the facelike pattern only when it was presented in the temporal hemifield. In Experiment 2, both patterns had the blobs in the inverted position. For one pattern the blobs were black, and for the other they were striped. Newborns preferentially oriented to the striped blobs in either hemifield. The results support the hypothesis that in newborns, preference for facelike patterns reflects the activity of a subcortical mechanism.

Four experiments are reported that were aimed at elucidating some of the controversial issues concerning the preference for facelike patterns in newborns. The experiments were devised to contrast the original and the revised versions of the sensory hypothesis and the structural hypothesis as accounts of face preference in newborns. Experiments 1A and 1B supported the structural hypothesis by showing a visual preference for the stimulus for which components were located in the correct arrangement for a human face. Experiment 2 supported the sensory hypothesis by showing a visual preference for stimuli that were designed to have the optimal spatial frequency components for the newborn visual system. Experiment 3 showed that babies directed attention to a facelike pattern also when it was presented simultaneously with a nonfacelike stimulus with optimal spatial frequency for the newborn visual system.