Visual completion of partly occluded grating in infants under 1 month of age

Perceptual Transparency in 3- to 4-Month-Old Infants

We examined perceptual transparency in infants. In a previous study, Johnson and Aslin (2000 Developmental Psychology36 808 – 816) found that 4-month-olds could perceive transparency in a moving chromatic display, but not in an achromatic display. In this study, we further examined perceptual transparency in infants using a static achromatic display. Considering the development of figural organisation and contrast sensitivity, we assumed that 3- to 4-month-olds would perceive transparency even in a static achromatic display. We created a transparency and a non-transparent display composed of a partially overlapping circle and square, by switching the colours. Infants aged 3 to 4 months ( n = 24) were familiarised with the transparency display (experiment 1) or with the non-transparent display (experiment 2). Then, they were confronted with a uniform colour and a two-colour figure. Infants showed novelty preference for the two-colour figure after they had been familiarised with the transparency display (experiment 1), but not after they had been familiarised with the non-transparent display (experiment 2). These results suggest that 3- to 4-month-old infants can perceive transparency in a static achromatic display.

Infant perception of object unity in static displays

The present study examined infants’ capability of extracting object unity in a stationary twodimensional rod-and-box display. The infants were habituated to a centre-occluded rod and were afterwards tested with both a broken rod and a complete rod. The looking pattern of both female and male participants aged 8 months did not reveal the ability to amodally complete the partly hidden rod. Nine-month-old females, however, looked reliably longer at the broken test stimulus than at the solid test display, implying that they had perceived the partially occluded rod presented in the habituation period as a connected whole. Their male counterparts, on the other hand, did not differentiate between the test patterns. These findings suggest that the capability of perceiving object unity in displays in which the relative depth ordering of surfaces is specified solely by the pictorial depth cue of interposition emerges after about 8 months of age. Furthermore, the results argue for a differential perspective including sex as a moderator variable.

Development of Modal and Amodal Completion in Infants

Visual completion has been divided into two types: modal and amodal. While psychophysical studies with adults provided several common properties between modal and amodal completion, studies with infants showed differential trends in the development of these perceptual abilities. In the present study, we further examined the development of these two kinds of visual completion in infants aged 3 to 6 months. We created a display composed of a partially overlapping circle and square. The display induced either modal or amodal completion depending on the colour. Infants were familiarised with either the modal or the amodal display. After this familiarisation, the infants were tested on their discrimination between the complete figure and the broken figure. If the infants could perceptually complete the figures in the familiarisation display, they were expected to show a novelty preference for the broken figure. A total of thirty-two infants participated in the present study. Our results suggest that modal completion develops by 3 – 4 months of age, whereas amodal completion develops by 5 – 6 months of age.

Die Entwicklung der räumlichen Wahrnehmung im Säuglingsalter: Eine Positionsbestimmung

Zusammenfassung. In den vergangenen Jahrzehnten ist eine Vielzahl experimenteller Studien mit dem Ziel durchgeführt worden, den Zeitpunkt der Entstehung der räumlichen Wahrnehmung im ersten Lebensjahr aufzuspüren. Ein Problem dieser Forschungsarbeiten besteht darin, dass sie auf keine einheitlichen Altersangaben hin konvergieren und so keine sicheren Schlussfolgerungen darüber zulassen, ab wann genau die jeweilige Wahrnehmungsleistung vorhanden ist. Insbesondere im Bereich der bildhaften Tiefenwahrnehmung gibt es eine vermeintliche Diskrepanz in den Ergebnissen von Studien, in denen die Methode des präferentiellen Greifens zur Anwendung kommt, und Studien, in denen das kindliche Blickverhalten beobachtet wird. Aufgabe der Forschung ist daher die Entwicklung und Anwendung von Heuristiken, mit deren Hilfe eine Klärung der Faktoren erfolgen kann, die für derartige unterschiedliche Befundlagen verantwortlich sind. Zu diesen Heuristiken zählen das Verfahren der metaanalytischen Auswertung vorhandener Ergebnisse sowie die Anwendung unterschiedlicher Untersuchungsmethoden und Versuchsdesigns auf einen Inhaltsbereich. Am Beispiel der bildhaften Tiefenwahrnehmung wird dargestellt, dass eine metaanalytische Vorgehensweise die Theorienbildung vorantreiben kann. Zudem werden unterschiedliche experimentelle Designs und Techniken der Datenerhebung skizziert und in ihrer Rolle für die Forschung erläutert.

Occlusion is hard: Comparing predictive reaching for visible and hidden objects in infants and adults

Infants can anticipate the future location of a moving object and execute a predictive reach to intercept the object. When a moving object is temporarily hidden by darkness or occlusion, 6-month-old infants' reaching is perturbed but performance on darkness trials is significantly better than occlusion trials. How does this reaching behavior change over development? Experiment 1 tested predictive reaching of 6- and 9-month-old infants. While there was an increase in the overall number of reaches with increasing age, there were significantly fewer predictive reaches during the occlusion compared to visible trials and no age-related changes in this pattern. The decrease in performance found in Experiment 1 is likely to apply not only to the object representations formed by infants but also those formed by adults. In Experiment 2 we tested adults with a similar reaching task. Like infants, the adults were most accurate when the target was continuously visible and performance in darkness trials was significantly better than occlusion trials, providing evidence that there is something specific about occlusion that makes it more difficult than merely lack of visibility. Together, these findings suggest that infants' and adults' capacities to represent objects have similar signatures throughout development.

Occlusion is hard: Comparing predictive reaching for visible and hidden objects in infants and adults

Infants can anticipate the future location of a moving object and execute a predictive reach to intercept the object. When a moving object is temporarily hidden by darkness or occlusion, 6-month-old infants' reaching is perturbed but performance on darkness trials is significantly better than occlusion trials. How does this reaching behavior change over development? Experiment 1 tested predictive reaching of 6- and 9-month-old infants. While there was an increase in the overall number of reaches with increasing age, there were significantly fewer predictive reaches during the occlusion compared to visible trials and no age-related changes in this pattern. The decrease in performance found in Experiment 1 is likely to apply not only to the object representations formed by infants but also those formed by adults. In Experiment 2 we tested adults with a similar reaching task. Like infants, the adults were most accurate when the target was continuously visible and performance in darkness trials was significantly better than occlusion trials, providing evidence that there is something specific about occlusion that makes it more difficult than merely lack of visibility. Together, these findings suggest that infants' and adults' capacities to represent objects have similar signatures throughout development.

The visual phantom illusion: a perceptual product of surface completion depending on brightness and contrast

The visual phantom illusion was first discovered by Rosenbach in 1902 and named 'moving phantoms' by Tynan and Sekuler in 1975 because of its strong dependence on motion. It was later revealed that phantoms can be generated by flickering the grating (flickering phantoms) or by low-luminance stationary gratings under dark adaptation (stationary phantoms). Although phantoms are much more visible at scotopic or mesopic adaptation levels (scotopic phantoms) than at photopic levels, we proposed a new phantom illusion which is fully visible in photopic vision (photopic phantoms). In 2001, we revealed that the visual phantom illusion is a higher-order perceptual construct or a Gestalt, which depends on the mechanism of perceptual transparency. Perceptual transparency is known as a perceptual product based upon brightness and contrast. We furthermore manifested the shared mechanisms between visual phantoms and neon color spreading or between visual phantoms and the Petter effect. In our recent study, the visual phantom illusion can also be seen with a stimulus of contrast-modulated gratings. We assume that this effect also depends on perceptual transparency induced by contrast modulation. Moreover, we found that the Craik-O'Brien-Cornsweet effect and other brightness illusions can generate the visual phantom illusion. In any case, we explain the visual phantom illusion in terms of surface completion, which is given by perceptual transparency.

Infants' perception of object trajectories

Filling in the gaps in what humans see is a fundamental perceptual skill, but little is known about the developmental origins of occlusion perception. Three experiments were conducted with infants between 2 and 6 months of age to investigate perception of the continuity of an object trajectory that was briefly occluded. The pattern of results across experiments provided little evidence of veridical responses to trajectory occlusion in the youngest infants, but by 6 months, perceptual completion was more robust. Four-month-olds' responses indicated that they perceived continuity under a short duration of occlusion, but when the object was out of sight for a longer interval, they appeared to perceive the trajectory as discontinuous. These results suggest that perceptual completion of a simple object trajectory (and, by logical necessity, veridical object perception) is not functional at birth but emerges across the first several months after onset of visual experience.

Connectivity perception of partly occluded gratings in 4-month-old infants

Four groups of eight 4-month-old infants were each habituated to one of four displays consisting of a grating of either low (0.4 cycle deg(-1) or high (1.2 cycles deg(-1) spatial frequency, whose central portion was covered up with a horizontal occluder which was either narrow (1.33 deg) or broad (4.17 deg). Posthabituation displays consisted of a complete grating of the same frequency as the habituated grating, along with a separate grating whose central portion was replaced with a black gap of the same height as the occluder in the habituation displays. All the infants, except those who were habituated to the high frequency with the broad occluder, looked longer at the separate grating than the complete grating display during posthabituation trials. Previously, we found that infants under 1 month of age perceive the grating continuation only when the occluder height is less than about 0.5 cycle of the grating; our present results show that this figure increases to about 1.6 cycles of the grating frequency in the case of 4-month-old infants. These findings indicate that those developmental changes depend on both the sufficiency of visual information available and the efficiency of the perceptual ability of infants for grasping spatial relationships.