Infants' perception of kinetic depth and stereokinetic displays.

Examined infants' perceptions of 3-dimensional form, using a kinetic depth effect (KDE) display and displays containing subsets of the motion present in the KDE display. One subset consisted of "between-contour" motion, and the second consisted of "within-contour" motion. Research with adults has suggested that only between-contour motion leads to a compelling depth percept. In Exps 1 and 2, infants generalized habituation from a KDE display to the between-contour but not the within-contour changes. In Exps 3 and 4, infants generalized habituation from a KDE display to the between-contour display viewed from a novel orientation but not to the within-contour display viewed from the original orientation. Results indicate sensitivity to between-contour but not within-contour information, suggesting that infants perceive the 3-dimensional form of these displays. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' encoding of kinetic displays varying in relative coherence.

Two experiments were conducted to assess 3-month-old infants' processing of moving point-light displays depicting the biomechanical motions of a person walking. The displays were computer-generated and varied in stimulus coherence as measured by a version of coding theory. An infant-control habituation paradigm was used to measure both encoding and discrimination of the stimuli. Experiment 1 involved two point-light displays with identical absolute motions but different degrees of relative coherence. The results revealed that these two displays were discriminable and that encoding was systematically related to their relative coherence. Experiment 2 revealed that two new displays varying less in their coherence were also differentially encoded but were not discriminated. It was concluded that infants' processing of kinetic displays varies as a function of their relative coherence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Judgments of relative motion in tactical displays.

Two experiments examined the speed with which the direction of relative motion could be inferred from static tactical displays. In Exp I, 12 25–40 yr old experienced right-handed male naval officers responded more rapidly to displays depicting target motion to the right than to the left, but 12 inexperienced officers did not. For both groups, 1 of the 3 tactical geometries yielded significantly longer response times than the others (a "tactic" effect). In Exp II, the influence of decision strategy on the tactic effect was evaluated in 18 22–52 yr old naive Ss. Control of strategy through instruction and order of problem presentation did not reduce the tactic effect but did interact with the directional bias related to target motion. The tactic effect is discussed in terms of directional incongruity among displayed and inferred stimulus elements. Implications for training are discussed. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' perception of object unity in translating and rotating displays

In 3 experiments, the authors examined the sensitivity of infants to the unity of a partly occluded moving rod undergoing translation, rotation, or oscillation. Four-month-old infants were sensitive to the unity of the partly occluded rod when it translated, but not when it rotated, behind an occluder. Six-month-old infants perceived the rotating rod as continuing behind the occluder, but they did not perceive the unity of a rod that oscillated back and forth behind the occluder. Finally, 6-month-old infants showed an ambiguous response to a rotating rod when the shape of the occluder was changed from rectangular to round. These findings suggest that all types of common motion are not equivalent for specifying infants' perceptions of occluded objects. Additional factors should be considered that take into account the information specified by different types of motion and by different conditions at the intersection of the occluder and the object.     

Infants' sensitivity to effects of gravity on visible object motion.

A preference method probed infants' perception of object motion on an inclined plane. Infants viewed videotaped events in which a ball rolled downward (or upward) while speeding up (or slowing down). The infants were tested with events in which the ball moved in the opposite direction with appropriate or inappropriate acceleration. Infants aged 7 mo, but not 5 mo, looked longer at the test event with inappropriate acceleration, suggesting emerging sensitivity to gravity. A further study tested whether infants appreciate that a stationary object released on an incline moves downward rather than upward; findings again were positive at 7 mo and negative at 5 mo. A final study provided evidence, nevertheless, that 5-mo-old infants discriminate downward from upward motion and relate downward motion in videotaped events to downward motion in live events. Sensitivity to certain effects of gravity appears to develop in infancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Young children can extend motion verbs to point-light displays.

In the first study using point-light displays (lights corresponding to the joints of the human body) to examine children's understanding of verbs, 3-year-olds were tested to see if they could perceive familiar actions that corresponded to motion verbs (e.g., walking). Experiment 1 showed that children could extend familiar motion verbs (e.g., walking and dancing) to videotaped point-light actions shown in the intermodal preferential looking paradigm. Children watched the action that matched the requested verb significantly more than they watched the action that did not match the verb. In Experiment 2, the findings of Experiment 1 were validated by having children spontaneously produce verbs for these actions. The use of point-light displays may illuminate the factors that contribute to verb learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accuracy of target detection in new-object and old-object displays.

In 4 experiments, the authors investigated accuracy of detecting a target among nontargets. In some experiments, the target was a second-order square of stationary lines on a background of downward-moving lines, and nontargets were second-order squares of upward-moving lines. In other experiments, target and nontarget squares and background were shades of gray. The principal comparison was between new and old object displays. In new-object displays, search items appeared abruptly and one might be a target. In old-object displays, search items appeared abruptly, and after a delay one might become a target. Search displays in both conditions terminated shortly after target onset. Except when target onset was associated with the sole luminance change in a display, targets were much better detected in new-than in old-object displays. It is suggested that object onsets elicit a brief stimulus-driven enhancement of attention to the new objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' detection of increments in low- and high-frequency noise

A visually reinforced operant paradigm was employed to examine the relationship between the difference limen (DL) for intensity and level of the standard during infancy. In Experiment 1, 7-month-old infants and adults detected increments in continuous noise presented via headphones at each of four levels ranging from 28 to 58 dB SPL. Noise stimuli were 2-octave bands centered at either 400 or 4000 Hz, and increments were 10 and 100 msec in duration. Infants' DLs were significantly larger than those of adult subjects and significantly larger for low- than for high-frequency stimuli. For the high-frequency noise band, infants' DLs were generally consistent with Weber's law, remaining essentially constant for standards higher than 28 dB SPL (3 dB SL) for 100-msec increments and 38 dB SPL (13 dB SL) for 10-msec increments. For low-frequency noise, infants' absolute thresholds were exceptionally high, and sensation levels of the standards were too low to adequately describe the relationship. In Experiment 2, 7-month-old infants detected 10- and 100-msec increments in 400-Hz noise stimuli presented in sound field. Infants' low-frequency DLs were large at low intensities and decreased with increases in level of the standard up to at least 30 dB SL. For both low- and high-frequency noise, the difference between DLs for 10- and 100-msec increments tended to be large at low levels of the standard and to decrease at higher levels. These results suggest that the relationship between the DL and level of the standard varies with both stimulus frequency and duration during infancy. However, stimulus-dependent immaturities in increment detection may be most evident at levels within approximately 30 dB of absolute threshold.     

Direction of motion relationships between controls and displays moving in different planes.

"… to investigate the direction of motion relationships for seven combinations of display pointer moving at right angles to plane of rotation of control knob, a total of 718 Ss were tested by sequential methods on an apparatus producing a single direction of movement of a pointer, moving along a linear scale, for either clockwise or anticlockwise rotation of the control… where the right hand was used, there was a significant tendency to turn the knob clockwise to produce movement away from the knob [but]… there was also a significant tendency for movement towards the knob to be mediated by clockwise turning… [there were, however] significantly more anticlockwise responses for movement towards the control… . Left-handed combinations gave rise to no significant tendencies; but left-handed Ss gave significantly more anticlockwise responses than right-handers, even when the right hand was used. On the whole it is not advisable to employ any of the combinations explored in this investigation, unless movement is to be restricted to adjustments in one direction only relative to the control." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental animation: Inferring motion from static displays of mechanical systems.

Analyzed reaction time (RT) and eye-fixation data to investigate how people infer the kinematics of simple mechanical systems (pulley systems) from diagrams showing their static configuration. It is proposed that this mental animation process involves decomposing the representation of a pulley system into smaller units corresponding to the machine components and animating these components in a sequence corresponding to the causal sequence of events in the machine's operation. Although it is possible for people to make inferences against the chain of causality in the machine, these inferences are more difficult, and people have a preference for inferences in the direction of causality. The mental animation process reflects both capacity limitations and limitations of mechanical knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' perception of transparency.

Four- and 7-month-old infants' perception of transparency was investigated with computer-generated achromatic or color displays depicting a semitransparent box occluding the center of a rod. Following habituation, infants viewed test displays consisting of either a two-color rod (corresponding to the habituation display's proximal characteristics) or a solid rod (corresponding to the distal characteristics of the event depicted by the habituation display). Looking-time results from 4-month-olds suggested perception of transparency in color displays but not in an achromatic display. An additional condition indicated that transparency perception may rely on the visibility of background texture through the transparent surface. Seven-month-olds, in contrast, provided some evidence of transparency perception in the achromatic display. Implications for the development of infants' responses to object properties and perceptual segregation are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' understanding of visible displacements.

Two studies examined 54 9-mo-old and 54 12-mo-old infants' understanding of visible displacements and whether infants understand that the object has been deleted from its initial hiding place as part of its displacement to a new location. Displacement problems were compared with 2-object problems on which separate objects were hidden at the 1st and 2nd hiding place so that the initial object was not deleted from the 1st displacement location. Nondisplacement problems, on which the object remained at the 1st hiding place while the experimenter moved her visibly empty hand to the 2nd place, were also included in the 1-object condition. Although Exp I showed equivocal results, Exp II provided clear evidence that even 9-mo-olds have at least a limited sensitivity to the deletion component of displacements. In that experiment, the 9-mo-olds searched significantly more at the 2nd than at the 1st hiding place on displacement problems, and the distribution of their searches across the 2 visited locations on those problems was significantly different than on 2-object problems. Although their performance was less consistent than that of 12-mo-olds, there was no evidence that they suffered from any systematic misunderstanding that separated them from the older Ss. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' acquisition of spatiotemporal expectations.

The microdevelopment of infants' visual expectations was examined by analysis of the eye movements that 80 three-month-old human infants made during interstimulus intervals (ISIs) of an alternating picture sequence. For comparison, identical eye movement data were gathered from 10 infants who watched an irregular sequence. Shifts during ISIs were exhibited by all infants and occurred on 48% of all trials. Initially, infants' ISI shifts repeated saccades that had successfully located the preceding picture; during the course of the alternating session, repetitive saccades declined while alternating and anticipatory saccades increased. For infants who saw the irregular sequence, the frequency of ISI shifts did not vary systematically over trials. Analysis of saccade latencies suggested that infants quickly learned to inhibit a prepotent tendency in order to execute task-appropriate saccades. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' detection of visual-tactual discrepancies: Asymmetries that indicate a directive role of visual information.

Infants' cross-modal functioning was investigated in two studies. In Study 1, 11-month-old infants were confronted with five different visual–tactual discrepancies created with a mirror arrangement. The infants' behavioral reactions to the discrepancies were compared with their behavior on matched control trials with a forced-choice judgment procedure. Infants detected discrepancies in which they saw an egg and felt a cube, saw a fur-covered cube and felt an egg, and saw a cross and felt a fur-covered cube. However, they provided no evidence that they detected discrepancies in which they saw a cube and felt a cross or saw a cube and felt a fur-covered cube. In Study 2, infants were confronted with discrepancies that were the converse of those which seemed to go unnoticed in Study 1: They saw either a cross or a fur-covered cube and felt a plain cube. Both of these new discrepancies were detected according to the forced-choice judgment procedure. The results indicate that texture as well as shape can serve as a basis for cross-modal matching for infants. The asymmetries in cross-modal matching that were observed across Studies 1 and 2 are interpreted as evidence that visual information plays a directive, goal-setting role for infants' manual explorations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' recognition memory for hue.

Fifty healthy 4-mo-old human infants with no family history of color vision deficiency participated in a study of recognition memory for hue. Five groups of 10 Ss each were first habituated to 1 wavelength of light and afterward tested for recognition with the original and 2 new spectral lights. Retention intervals between habituation and test included short- and long-term delays as well as long-term delays with different types of retroactive interference. The pattern of results was consistent across groups: Within experimental limits, Ss' recognition memory for hue was quite resilient to interference or delay. The stable results obtained when trial and intertrial interval lengths were reduced by one third suggest that reliable measures may be obtained in visual habituation paradigms with the shorter experimental session. Results replicate the previous report of M. H. Bornstein et al (1976) concerning the tendency of infants to categorize wavelength according to hue. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' intermodal knowledge about gender.

The aim of this study was to seek evidence of intermodal knowledge about gender in infants that would provide direct evidence of the existence of gender categories during the 1st yr of life. In Exp 1, 20 9- and 24 12-mo-olds were presented with pairs of male and female pictures with a female or male voice presented simultaneously. Ss spent significantly more time looking at the pictures matching the voices than at the same pictures paired with mismatching voices, but only in the case of female stimuli. Comparison to chance level performance suggested that the matching effect was more consistent in older Ss. In Exp 2, 20 9-mo-olds were tested with a set of highly stereotypical faces and distinctive male and female voices. Ss showed a preference for the faces matching the voices, but this effect was again restricted to female stimuli. Results of both studies suggest that intermodal knowledge about gender develops during the 2nd half of the 1st yr. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stability in Young Infants' Discrimination of Optic Flow.

Although considerable progress has been made in understanding how adults perceive their direction of self-motion, or heading, from optic flow, little is known about how these perceptual processes develop in infants. In 3 experiments, the authors explored how well 3- to 6-month-old infants could discriminate between optic flow patterns that simulated changes in heading direction. The results suggest that (a) prior to the onset of locomotion, the majority of infants discriminate between optic flow displays that simulate only large (> 22°) changes in heading, (b) there is minimal development in sensitivity between 3 and 6 months, and (c) optic flow alone is sufficient for infants to discriminate heading. These data suggest that spatial abilities associated with the dorsal visual stream undergo prolonged postnatal development and may depend on locomotor experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discriminability of random-dot stereograms in three-dimensional space

The discriminability of crossed-disparity (near) and uncrossed-disparity as a function of their location in the upper-left, upper-right, lower-left, and lower-right quadrants of the visual field. Discriminability was assessed using choice reaction-time (RT) and accuracy measures. While near targets were recognized equally well in the upper and lower fields, far targets were perceived more easily in the upper visual field. The discriminability of far targets was particularly poor in the lower left quadrant. These results point to the existence of fundamental asymmetries in perceiving crossed and uncrossed disparities along the vertical and lateral axes.     

Infants' use of object parts in early categorization.

Two experiments involving object-manipulation tasks were performed to examine whether 1- to 2 year-olds form superordinate-like categories by attending to object parts. In Study 1, 14-, 18-, and 22-month-olds were tested with contrasts of animals, furniture, insects, and vehicles. Fourteen- and 18-month-olds behaved systematically toward categories with different parts (legs or wheels) but not toward categories with matching parts (legs or legs). In Study 2, infants were tested with novel animals and vehicles generated by removing or attaching legs or wheels. In the absence of part differences, all three age groups failed to form superordinate categories. The two younger groups chose to categorize by parts (i.e., legs or wheels) rather than by category membership (animal or vehicle). The results suggest a perceptual basis for categorization whereby infants form dynamic categories, on-line, that are based on the characteristics of the input. (PsycINFO Database Record (c) 2010 APA, all rights reserved)