Young infants' perception of the trajectories of two- and three-dimensional objects

We investigated oculomotor anticipations in 4-month-old infants as they viewed center-occluded object trajectories. In two experiments, we examined performance in two-dimensional (2D) and three-dimensional (3D) dynamic occlusion displays and in an additional 3D condition with a smiley face as the moving target stimulus. Rates of anticipatory eye movements were not facilitated by 3D displays or by the (presumably) more salient smiley face relative to the 2D condition. However, latencies of anticipations were reduced, implying that 3D visual information may have supported formation of more robust mental representations of the moving object. Results are interpreted in a context of perceptual constraints on developing cognitive capacities during early infancy.

The role of association in early word-learning

Word-learning likely involves a multiplicity of components, some domain-general, others domain-specific. Against the background of recent studies that suggest that word-learning is domain-specific, we investigated the associative component of word-learning. Seven- and 14-month-old infants viewed a pair of events in which a monkey or a truck moved back and forth, accompanied by a sung syllable or a tone, matched for pitch. Following habituation, infants were presented with displays in which the visual-auditory pairings were preserved or switched, and looked longer at the "switch" events when exposure time was sufficient to learn the intermodal association. At 7 months, performance on speech and tones conditions was statistically identical; at 14 months, infants had begun to favor speech. Thus, the associative component of word-learning does not appear (in contrast to rule-learning, Marcus et al., 2007) to initially privilege speech.

Trajectory perception and object continuity: effects of shape and color change on 4-month-olds' perception of object identity

Previous work has demonstrated that infants use object trajectory continuity as a cue to the constant identity of an object, but results are equivocal regarding the role of object features, with some work suggesting that a change in the appearance of an object does not cue a change in identity. In an experiment involving 72 participants, we investigated the effects of changing object shape and color, singly and in combination, on 4-month-olds' perception of object continuity. A change in the shape of an object while it passed behind an occluder had no effect on perception of continuity, whereas a change in shape and color led to perception of discontinuity, and a change in color led to no clear percept regarding continuity or discontinuity. These results are discussed in terms of a perceptual learning model of development of object identity.

The effects of auditory information on 4-month-old infants' perception of trajectory continuity

Young infants perceive an object's trajectory as continuous across occlusion provided the temporal or spatial gap in perception is small. In 3 experiments involving 72 participants the authors investigated the effects of different forms of auditory information on 4-month-olds' perception of trajectory continuity. Provision of dynamic auditory information about the object's trajectory enhanced perception of trajectory continuity. However, a smaller positive effect was also obtained when the sound was continuous but provided no information about the object's location. Finally, providing discontinuous auditory information or auditory information that was dislocated relative to vision had negative effects on trajectory perception. These results are discussed relative to the intersensory redundancy hypothesis and emphasize the need to take an intersensory approach to infant perception.

The effects of auditory information on 4-month-old infants' perception of trajectory continuity

Young infants perceive an object's trajectory as continuous across occlusion provided the temporal or spatial gap in perception is small. In 3 experiments involving 72 participants the authors investigated the effects of different forms of auditory information on 4-month-olds' perception of trajectory continuity. Provision of dynamic auditory information about the object's trajectory enhanced perception of trajectory continuity. However, a smaller positive effect was also obtained when the sound was continuous but provided no information about the object's location. Finally, providing discontinuous auditory information or auditory information that was dislocated relative to vision had negative effects on trajectory perception. These results are discussed relative to the intersensory redundancy hypothesis and emphasize the need to take an intersensory approach to infant perception.

Sound support: intermodal information facilitates infants' perception of an occluded trajectory

In a visual occlusion task, 4-month-olds were given a dynamic sound cue (following the trajectory of an object), or a static cue (sound remained stationary). Infants' oculomotor anticipations were greater in the Dynamic condition, suggesting that representations of visual occlusion were supported by auditory information.

Association between vitamin D and diabetic neuropathy in a nationally representative sample: results from 2001-2004 NHANES

AIMS

To evaluate the association between vitamin D insufficiency and peripheral neuropathy in a nationally representative sample of adults with diagnosed diabetes.

METHODS

Vitamin D concentrations, medical examination variables and questionnaire results from the 2001-2004 National Health and Nutrition Examination Survey were analysed for adults ≥ 40 years old with diagnosed diabetes (unweighted n = 591, weighted n = 8.82 million). Neuropathy was defined as self report of peripheral neuropathy symptoms of painful sensation, tingling, numbness or loss of feeling in hands or feet. Additionally, Semmes-Weinstein monofilament test results were used as an indicator of neuropathy. Insufficient vitamin D was characterized as < 30 ng/ml.

RESULTS

In the weighted population, 81% of adults with diabetes had vitamin D insufficiency. Vitamin D insufficiency was more common among Hispanics (92%) and non-Hispanic black people (98%) than among non-Hispanic white people (76%). Within the 3 months preceding the questionnaire, 50% reported experiencing pain or numbness (paresthesia) in their hands or feet; 37% reported pain or tingling in hands or feet; and 38% reported numbness or loss of feeling in hands or feet. Eight per cent had 4-6 insensate areas on their feet as determined by the Semmes-Weinstein monofilament test. Logistic regressions demonstrate vitamin D insufficiency is associated with the adjusted composite paresthesia measure (odds ratio 2.12; 95% CI 1.17-3.85) and the adjusted numbness measure (odds ratio 2.04; 95% CI 1.18-3.52).

CONCLUSIONS

Vitamin D insufficiency is associated with self-reported peripheral neuropathy symptoms even after adjusting for demographic factors, obesity, co-morbidities, use of medications for neuropathy and diabetes duration and control.

Infants' perception of object-surface interplays

Twelve- and 18-month-old infants participated in a study designed to investigate the quality of their manual action when relating an object to the surface on which it is explored. Specifically, infants' perception-action routines were observed when they were presented with multiple objects (wooden scoop, Velcro block, and crayon) on surfaces of varying properties (paper, sand, and Velcro) to determine if sensory feedback or perceptual awareness steered their exploration of the available materials. Infants were observed to selectively tailor their manual actions across conditions, apparently guided by a perceived awareness of the fit between their manual dexterity and the environmental arrangement.

A Critical Test of Temporal and Spatial Accuracy of the Tobii T60XL Eye Tracker

Infant eye tracking is becoming increasingly popular for its presumed precision relative to traditional looking time paradigms and potential to yield new insights into developmental processes. However, there is strong reason to suspect that the temporal and spatial resolution of popular eye tracking systems is not entirely accurate, potentially compromising any data from an infant eye tracking experiment. Moreover, "best practices" for infant eye tracking, such as knowing which software tool enhances experimental flexibility, remain to be determined. The present investigation was designed to evaluate the temporal and spatial accuracy of data from the Tobii T60XL eye tracker through the use of visual latency and spatial accuracy tasks involving adults and infants. Systematic delays and drifts were revealed in oculomotor response times, and the system's spatial accuracy was observed to deviate somewhat in excess of the manufacturer's estimates; the experimental flexibility of the system appears dependent on the chosen software.

Mental Rotation of Dynamic, Three-Dimensional Stimuli by 3-Month-Old Infants

Mental rotation involves transforming a mental image of an object so as to accurately predict how the object would look if it were rotated in space. This study examined mental rotation in male and female 3-month-olds, using the stimuli and paradigm developed by Moore & Johnson (2008). Infants were habituated to a video of a 3-dimensional object rotating back and forth through a 240° angle around the vertical axis. After habituation, infants were tested both with videos of the same object rotating through the previously unseen 120° angle, and with the mirror image of that display. Unlike females, who fixated the test displays for approximately equal durations, males spent significantly more time fixating the familiar object than the mirror-image object. Because familiarity preferences like this emerge when infants are relatively slow to process a habituation stimulus, the data support the interpretation that mental rotation of dynamic 3-dimensional stimuli is relatively difficult-but possible-for 3-month-old males. Interpretation of the sex differences observed in 3- and 5-month-olds' performances is discussed.

Two- to eight-month-old infants' perception of dynamic auditory-visual spatial colocation

From birth, infants detect associations between the locations of static visual objects and sounds they emit, but there is limited evidence regarding their sensitivity to the dynamic equivalent when a sound-emitting object moves. In 4 experiments involving thirty-six 2-month-olds, forty-eight 5-month-olds, and forty-eight 8-month-olds, we investigated infants' ability to process this form of spatial colocation. Whereas there was no evidence of spontaneous sensitivity, all age groups detected a dynamic colocation during habituation and looked longer at test trials in which sound and sight were dislocated. Only 2-month-olds showed clear sensitivity to the dislocation relation, although 8-month-olds did so following additional habituation. These results are discussed relative to the intersensory redundancy hypothesis and work suggesting increasing specificity in processing with age.

Development of visual perception

Processes of visual development that yield a view of the world as coherent and stable begin well before birth and extend over the first several years after the onset of visual experience. Infants are born capable of seeing and with specific preferences that guide the point of gaze to relevant portions of the visual scene to support learning about objects and faces. Visual development after birth is characterized by critical periods in many notable visual functions, and by extensive learning from experience and increasing control over eye movement systems. WIREs Cogni Sci 2011 2 515-528 DOI: 10.1002/wcs.128 For further resources related to this article, please visit the WIREs website.

The role of perceptual and cognitive processes in addition-subtraction studies with 5-month-old infants

After a brief familiarization period to either one or two toys 5-month-olds gave a clear preference for perceptually novel displays, suggesting that replicable findings of greater looking at an unexpected arithmetic outcome in addition/subtraction experiments cannot easily be attributed to simple familiarity preferences.

How Infants Learn About the Visual World

The visual world of adults consists of objects at various distances, partly occluding one another, substantial and stable across space and time. The visual world of young infants, in contrast, is often fragmented and unstable, consisting not of coherent objects but rather surfaces that move in unpredictable ways. Evidence from computational modeling and from experiments with human infants highlights three kinds of learning that contribute to infants' knowledge of the visual world: learning via association, learning via active assembly, and learning via visual-manual exploration. Infants acquire knowledge by observing objects move in and out of sight, forming associations of these different views. In addition, the infant's own self-produced behavior-oculomotor patterns and manual experience, in particular-are important means by which infants discover and construct their visual world.

Participatory management: Maintaining staff performance in a university housing cooperative

To apply behavior analysis to normal adults in non institutional settings, we may have to encourage their participation in the design and implementation of behavioral technology. This study evaluates a technology by which the members of a student housing cooperative manage their own staff with a minimum of supervision by one of the program designers. This staff management system consisted of prompts, self-reports, spot checks, and contingent rent reductions. Six resident staff members performed substantially more of their assigned tasks when this system was used. In addition, the management system was acceptable to the members, was affordable, and maintained high levels of staff performance during a 5-year follow-up. Participation by the members in the design and implementation of this system appears to have been useful in helping the behavior analysts to develop an unusually durable management system.

Systems in development: motor skill acquisition facilitates three-dimensional object completion

How do infants learn to perceive the backs of objects that they see only from a limited viewpoint? Infants' 3-dimensional object completion abilities emerge in conjunction with developing motor skills--independent sitting and visual-manual exploration. Infants at 4.5 to 7.5 months of age (n = 28) were habituated to a limited-view object and tested with volumetrically complete and incomplete (hollow) versions of the same object. Parents reported infants' sitting experience, and infants' visual-manual exploration of objects was observed in a structured play session. Infants' self-sitting experience and visual-manual exploratory skills predicted looking at the novel, incomplete object on the habituation task. Further analyses revealed that self-sitting facilitated infants' visual inspection of objects while they manipulated them. The results are framed within a developmental systems approach, wherein infants' sitting skill, multimodal object exploration, and object knowledge are linked in developmental time.

Preverbal infants' sensitivity to synaesthetic cross-modality correspondences

Stimulation of one sensory modality can induce perceptual experiences in another modality that reflect synaesthetic correspondences among different dimensions of sensory experience. In visual-hearing synaesthesia, for example, higher pitched sounds induce visual images that are brighter, smaller, higher in space, and sharper than those induced by lower pitched sounds. Claims that neonatal perception is synaesthetic imply that such correspondences are an unlearned aspect of perception. To date, the youngest children in whom such correspondences have been confirmed with any certainty were 2- to 3-year-olds. We examined preferential looking to assess 3- to 4-month-old preverbal infants' sensitivity to the correspondences linking auditory pitch to visuospatial height and visual sharpness. The infants looked longer at a changing visual display when this was accompanied by a sound whose changing pitch was congruent, rather than incongruent, with these correspondences. This is the strongest indication to date that synaesthetic cross-modality correspondences are an unlearned aspect of perception.

Information from multiple modalities helps 5-month-olds learn abstract rules

By 7 months of age, infants are able to learn rules based on the abstract relationships between stimuli (Marcus et al., 1999), but they are better able to do so when exposed to speech than to some other classes of stimuli. In the current experiments we ask whether multimodal stimulus information will aid younger infants in identifying abstract rules. We habituated 5-month-olds to simple abstract patterns (ABA or ABB) instantiated in coordinated looming visual shapes and speech sounds (Experiment 1), shapes alone (Experiment 2), and speech sounds accompanied by uninformative but coordinated shapes (Experiment 3). Infants showed evidence of rule learning only in the presence of the informative multimodal cues. We hypothesize that the additional evidence present in these multimodal displays was responsible for the success of younger infants in learning rules, congruent with both a Bayesian account and with the Intersensory Redundancy Hypothesis.

Mental rotation in human infants: a sex difference

A sex difference on mental-rotation tasks has been demonstrated repeatedly, but not in children less than 4 years of age. To demonstrate mental rotation in human infants, we habituated 5-month-old infants to an object revolving through a 240 degrees angle. In successive test trials, infants saw the habituation object or its mirror image revolving through a previously unseen 120 degrees angle. Only the male infants appeared to recognize the familiar object from the new perspective, a feat requiring mental rotation. These data provide evidence for a sex difference in mental rotation of an object through three-dimensional space, consistently seen in adult populations.

Bifunctional DNA alkylator 1,3-bis(2-chloroethyl)-1-nitrosourea activates the ATR-Chk1 pathway independently of the mismatch repair pathway

The presence of DNA damage initiates signaling through the ataxia-telangiectasia mutated kinase (ATM) and the ATM- and the Rad3-related kinase (ATR), which phosphorylate, thus activating, the checkpoint kinases (Chk) 1 and 2, which leads to cell cycle arrest. The bifunctional DNA alkylator 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) is cytotoxic primarily by inducing DNA monoadducts and ultimately, interstrand cross-links, which block DNA replication. In this study, we investigated the activation of the ATR-Chk1 pathway in response to BCNU treatment and the dependence of this response on the DNA mismatch repair (MMR) capacity. Medulloblastoma cells were exposed to low and moderate doses of BCNU, and the effects on this DNA damage signaling pathway were examined. In response to BCNU, Chk1 was found to be phosphorylated at serine 345 and exhibited increased kinase activity. Caffeine and wortmannin, which are broad-spectrum inhibitors of ATM and ATR, reduced this phosphorylation. Cell cycle analysis further revealed an accumulation of cells in the S phase in response to BCNU, an effect that was attenuated by caffeine. Small interfering RNA knockdown of ATR also reduced Chk1 phosphorylation after exposure to BCNU. However, knockdown of ATM had no effect on the observed Chk1 phosphorylation, suggesting that ATR was primarily responsible for Chk1 activation. Analysis of Chk1 activation in cells deficient in MMR proteins MutLalpha or MutSalpha indicated that the DNA damage response induced by BCNU was independent of the MMR apparatus. This MMR-independent activation seems to be the result of DNA interstrand cross-link formation.

Development of three-dimensional object completion in infancy

Three-dimensional (3D) object completion was investigated by habituating 4- and 6-month-old infants (n= 24 total) with a computer-generated wedge stimulus that pivoted 15 degrees , providing only a limited view. Two displays, rotating 360 degrees , were then shown: a complete, solid volume and an incomplete, hollow form composed only of the sides seen during habituation. There were no reliable preferences for either test display by 4-month-olds. At 6 months, infants showed a reliable novelty preference for the incomplete test display. Infants in a control group (n= 24) not habituated to the limited-view wedge preferred neither test display. By 6 months, infants may represent simple objects as complete in 3D space despite a limited perspective. Possible mechanisms of development of 3D object completion are discussed.

Abstract Rule Learning for Visual Sequences in 8- and 11-Month-Olds

The experiments reported here investigated the development of a fundamental component of cognition: to recognize and generalize abstract relations. Infants were presented with simple rule-governed patterned sequences of visual shapes (ABB, AAB, and ABA) that could be discriminated from differences in the position of the repeated element (late, early, or nonadjacent, respectively). Eight-month-olds were found to distinguish patterns on the basis of the repetition, but appeared insensitive to its position in the sequence; 11-month-olds distinguished patterns over the position of the repetition, but appeared insensitive to the nonadjacent repetition. These results suggest that abstract pattern detection may develop incrementally in a process of constructing complex relations from more primitive components.

Learning and memory facilitate predictive tracking in 4-month-olds

We investigated 4-month-olds' oculomotor anticipations when viewing occlusion stimuli consisting of a small target that moved back and forth repetitively while the center of its trajectory was occluded by a rectangular screen. We examined performance under five conditions. In the baseline condition, infants produced few predictive relative to reactive eye movements. In the full training condition, anticipations were increased in frequency following prior exposure to a target moving along a fully visible trajectory. The delay condition tested the effects of training after a 30-min interval elapsed between training and test, resulting in a return to baseline performance. However, the training effect was reinstated in the reminder condition following another brief exposure to the training stimulus prior to test. Finally, in the brief training condition, we found that the brief exposure alone was insufficient to induce the training effect. Results are interpreted in the context of learning from short-term experience and long-term memory.