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Early development of object unity: Newborn’s evidence for perceptual completion
No full textThe present study aimed to investigate whether perceptual completion is available at birth, in the absence of any visual
experience. An extremely underspecified kinetic visual display composed of four spatially separated fragments arranged to give rise to an illusory rectangle that occluded a vertical rod (illusory condition) or rotated so as not to elicit perceptual grouping (control condition) was constructed. After newborns’ ability to detect the particular kind of rod-and-box display used in the present study had been probed (Experiment 1), they were habituated to the illusory rod-and-box display (Experiment 2), to the control display that did not contain illusory contours (Experiment 3), and to a standard real rod-and-box display akin to those used in previous infants’ studies (Experiment 4). Newborns perceived the rod as a connected unit either in the illusory condition (Experiment 2) or in the real condition (Experiment 4), as documented by a preference for a broken rod over a complete rod during the test phase, but not when the occluder was absent (Experiment 3). In all experiments newborns showed no preference between the two test stimuli (control condition), avoiding the possibility that newborns have a spontaneous preference for one test display over the other. Overall, the results of the present study provide evidence that the ability to achieve object unity (1) stems from intrinsic properties of the human perceptual system and (2) is operative from birth, given the right conditions
Attentional mechanisms involved in the selection of an illusory and a non illusory figure.
No full text
Object-based visual attention in 8-month-old infants: Evidence from an eye-tracking study
No full textVisual attention is one of the infant's primary tools for gathering relevant information from the environment for further processing and learning. The space-based component of visual attention in infants has been widely investigated; however, the object-based component of visual attention has received scarce interest. This scarcity is surprising, given the importance of objects in driving infants' attention and predispositions to attend to object information. Here, we investigated the object-based component of attention in 8-month-old infants. An eye tracker measured the saccade latencies to find a target that could appear in a previously cued end of 2 bars (valid targets), in the other end of the cued bar (invalid same-object targets), or in the other bar but at the same distance from the cue (invalid different-object targets). Bars were unoccluded or partly occluded; if attention is object based, it should also operate on objects that require perceptual completion. After verifying in a sample of adults (Experiment 1) that a measure of saccade latency suitably assessed space-based and object-based attention, we tested 8-month-old infants (Experiment 2) using the same procedure. The results showed that in both adults and infants, target detection was faster for valid targets than for invalid ones (space-based effect). Moreover, for both the unoccluded and partly occluded conditions, detection was faster on invalid within-object trials than on invalid between-objects trials (object-based effect). These findings demonstrate that visual objects can operate as units of attention for infants by the age of 8 months, offering implications for cognitive development
The visual search of an illusory figure: A comparison between 6-month-old infants and adults
No full textThe aim of the present study was to investigate how perceptual binding and selective attention operate during infants' and adults' visual search of an illusory figure. An eye-tracker
system was used to test adults and infants in two conditions: illusory and non-illusory (real). In the illusory condition, a Kanizsa triangle was embedded among distractor pacmen which
did not generate illusory contours. In the non-illusory condition, a real triangle was included in the same pacmen's display. The results showed that adults detected both the Kanizsa and the
real figure automatically and without focal attention (experiment 1). In contrast, 6-month-old infants showed a pop-out effect only for the real figure (experiment 2). The failure of the illusory
figure to trigger infants' attention was not due to infants' inability to perceive the illusory figure per se, as infants preferred the illusory figure over a non-illusory control stimulus in a classical
preferential-looking task (experiment 3). Overall, these findings indicate that the illusory Kanizsa triangle triggers visual attention in adults, but not in infants, supporting evidence that at 6 months
of age the binding processes involved in the perception of a Kanizsa figure do not operate in an adult-like manner
Newborns' face recognition over changes in viewpoint.
No full textThe 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
Visual statistical learning in the newborn infant
No full textStatistical learning – implicit learning of statistical regularities within sensory input – is a way of acquiring structure within continuous sensory environments. Statistics computation, initially shown to be involved in word segmentation, has been demonstrated to be a general mechanism that operates across domains, across time and space, and across species. Recently, statistical leaning has been reported to be present even at birth when newborns were tested with a speech stream. The aim of the present study was to extend this finding, by investigating whether newborns’ ability to extract statistics operates in multiple modalities, as found for older infants and adults. Using the habituation procedure, two experiments were carried out in which visual sequences were presented. Results demonstrate that statistical learning is a general mechanism that extracts statistics across domain since the onset of sensory experience. Intriguingly, present data reveal that newborn learner’s limited cognitive resources constrain the functioning of statistical learning, narrowing the range of what can be learned
A predisposition for biological motion displays in the newborn babies
No full textAn inborn predisposition to attend to biological motion has long
been theorized, but had so far been demonstrated only in one
animal species (the domestic chicken). In particular, no preference
for biological motion was reported for human infants of <3
months of age. We tested 2-day-old babies’ discrimination after
familiarization and their spontaneous preferences for biological vs.
nonbiological point-light animations. Newborns were shown to be
able to discriminate between two different patterns of motion
(Exp. 1) and, when first exposed to them, selectively preferred to
look at the biological motion display (Exp. 2). This preference was
also orientation-dependent: newborns looked longer at upright
displays than upside-down displays (Exp. 3). These data support
the hypothesis that detection of biological motion is an intrinsic
capacity of the visual system, which is presumably part of an
evolutionarily ancient and nonspecies-specific system predisposing
animals to preferentially attend to other animals
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