Martha E. Arterberry

Perception of three-dimensional shape specified by optic flow by 8-week-old infants

Sensitivity of 8-week-old infants to optical flow specifying the shape of a three-dimensional object was assessed. Infants viewed kinetic random-dot displays that specified three-dimensional cubes. The cubes were identical except for the presence or absence of an interior corner. Half of the infants viewed the full display. The other half viewed the central region of the displays, where the flow specifying the presence or absence of the corner differed. Infants in the full-view condition looked significantly longer to a novel cube than to the familiar cube following habituation. In contrast, infants in the partial-view condition looked equally to the novel and familiar cubes, ruling out the possibility that infants who viewed the full displays merely discriminated differences in motion in the central region of the two displays. These findings suggest that infants as young as 8 weeks perceive three-dimensional object shape from optic flow.

Infant perceptual and conceptual categorization: the roles of static and dynamic stimulus attributes

Infants categorization of animals and vehicles based on static vs. dynamic attributes of stimuli was investigated in five experiments (N=158) using a categorization habituation-of-looking paradigm. In Experiment 1, 6-month-olds categorized static color images of animals and vehicles, and in Experiment 2, 6-month-olds categorized dynamic point-light displays showing only motions of the same animals and vehicles. In Experiments 3, 4, and 5, 6- and 9-month-olds were tested in an habituation-transfer paradigm: half of the infants at each age were habituated to static images and tested with dynamic point-light displays, and the other half were habituated to dynamic point-light displays and tested with static images. Six-month-olds did not transfer. Only 9-month-olds who were habituated to dynamic displays showed evidence of category transfer to static images. Together the findings show that 6-month-olds categorize animals and vehicles based on static and dynamic information, and 9-month-olds can transfer dynamic category information to static images. Transfer, static vs. dynamic information, and age effects in infant categorization are discussed.

Infants' sensitivity to accretion and deletion of texture as information for depth at an edge.

Based on Gibsons hypothesis that accretion and deletion of texture in the optic array provides unambiguous information for the spatial layout of surfaces, we sought evidence of early responsiveness to this information with infant subjects. 5- and 7-month-olds viewed computer-generated random-dot displays in which accretion and deletion of texture provided the only information for contours, specifying either a foreground surface moving in front of and occluding a moving background surface or 2 partially overlapping surfaces. The infants in both age groups showed significant preferences to reach for the apparently nearer regions in the displays. Since previous research has shown that infants reach more frequently for the nearer of 2 surfaces, these results indicate that 5- and 7-month-olds are sensitive to accretion and deletion of texture as information for the spatial layout of surfaces.

Infants’ sensitivity to kinetic information for three-dimensional object shape

Infant sensitivity to kinetic information specifying three-dimensional object shape was assessed using computer-generated random-dot displays. Four-month-old infants were habituated to displays of an object oscillating about two different axes on alternating trials. Following habituation, the infants were tested for recovery from habituation to a display of the same object and a novel object. Both test displays employed a new axis of rotation. The infants generalized habituation to the same object and increased their looking to the new object. These results provide evidence that infants are sensitive to motion-carried information specifying three-dimensional object shape, since the random-dot displays minimized static information that differentiated the two objects. These findings suggest that, at least by 4 months of age, infants can detect subtle differences in shape from purely kinetic information.

Infants' distance perception from linear perspective and texture gradients☆

Abstract This study investigated 5- and 7-month-old infants abilities to perceive objects distances from pictorial depth cues, the depth cues available to a stationary, monocular viewer. Infants viewed a display in which texture gradients and linear perspective, two pictorial depth cues, created an illusion of two objects resting at different distances on a textured surface. Under monocular viewing conditions, 7-month-olds reached preferentially for the apparently nearer object, indicating that they perceived the objects relative distances specified by pictorial depth cues. Under binocular viewing conditions, these infants showed no reaching preference. This finding rules out interpretations of the results not based on the objects perceived distances. The 5-month-olds reaching preferences were not significantly different in the experimental (monocular) and control (binocular) conditions. These infants, therefore, did not show clear evidence of distance perception from pictorial depth cues.

Emergence of sensitivity to pictorial depth cues: Charting development in individual infants

Abstract Three experiments were conducted to explore the emergence of sensitivity to the pictorial depth cues of texture gradient and linear perspective. In experiment 1, an initial longitudinal study explored the emergence of sensitivity to pictorial depth information between 5 and 7 months of age. In experiment 2, a cross-sectional study with 5–7-month-olds assessed revised methods designed to study development of pictorial depth sensitivity in individual infants. Experiment 3 applied these methods to a second sample of infants studied longitudinally. The results showed that: (a) a reliable method for assessing sensitivity in individual infants has been constructed; (b) there is variability in the age at which infants begin to use linear perspective and texture gradient for perceiving depth (22–28 weeks of age); and (c) sensitivity emerges across 2–8 weeks.

Infants Perceive Spatial Structure Specified by Line Junctions

Lines in drawings can be perceived as the corners where surfaces intersect, outer boundaries of surfaces, or as markings on a surface. In this study infants ability to distinguish between lines that indicate corners and edges and lines that indicate markings was investigated. Infants aged 7.5 months were habituated to line displays in which the lines specified a three-dimensional cube or two overlapping rectangles. Both displays contained lines indicating corners, edges, and surface markings. After habituation, infants viewed two test displays, one in which the corners or edges were deleted and one in which the surface markings were deleted. Infants looked significantly longer at the displays that lacked the corners or edges. The results suggest that infants attend to lines that depict corners and edges to a greater degree than they attend to lines that depict markings. Infants may do so because corners and edges specify the shapes of objects whereas markings do not.

Self-produced locomotion and the development of responsiveness to linear perspective and texture gradients

Replicated and extended research on the development of sensitivity to the depth cues of linear perspective and texture gradients by using a more sensitive method (Experiment 1) and by investigating the role of self-produced locomotion in facilitating the onset of sensitivity to information (Experiment 2). Using a method similar to Yonas, Granrud, Arterberry, and Hanson (1986), infants reaching to the pictorially closer object served as the dependent measure. Changes in methodology provided an increase in the difference between 7-month-olds monocular and binocular reaching performance, but 5-month-olds failed to show evidence of sensitivity to the depth cues investigated. Experiment 2 found no difference in monocular reaching performance among 7-month-old infants with varying degrees of locomotor experience, suggesting that self-produced locomotion may not play a role in facilitating the onset of sensitivity to static-monocular depth information.

Variability and its sources in infant categorization

Abstract Variability of infants’ categorization performance and potential sources of this variability were investigated. Using data from 13 categorization studies employing a habituation-of-looking paradigm with infants 3, 5, 6, and 9 months of age, a method for establishing a categorization criterion was developed and then used to classify individual infants as “categorizers” for particular tasks. Logistic regression analyses were then used to identify demographic and information-processing variables that predicted “categorizer” classification. Variables that increased the odds of being classified as a categorizer were gender, number of habituation trials, and duration of peak look during habituation; total looking time during habituation decreased the odds of categorizer classification. These findings are discussed in the context of individual differences in information processing.

Imagery-induced interference on a visual detection task.

The literature on the interaction between visual imagery and visual perception provides conflicting outcomes. Some studies show imagery interferes with perception whereas others show facilitation on perceptual tasks. The effects of visual imagery on a detection task were examined in six experiments. When either a bar image (Experiment 1) or an image of the letter l (Experiment 3) overlapped with the targets, interference was discovered; however, images not overlapping the target did not effect detection (Experiments 2 and 4). Increasing the number of target locations caused the interfering effects of the image to disappear; however, there was no evidence of facilitation (Experiment 5). Physical stimuli interfered with detection whether there was overlap or not (Experiment 6). The results indicate that imagery induced interference may be lessened with more complex visual displays.