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To date, very little is known about the normal development trajectory of visual texture segregation, or how it is affected by preterm birth. The goal of this study was to characterize the development of visual texture segregation using texture segregation visual evoked potentials (tsVEPs) in children born full-term and children born preterm without major neurological impairment. Forty-five full-term and 43 preterm children were tested at either 12, 24 or 36 months of age (corrected age for prematurity at 12 and 24 months old). VEPs were obtained using two lower-level stimuli defined by orientation (oriVEP) and two higher-level stimuli defined by texture (texVEP). TsVEP was obtained by dividing by two the subtraction of oriVEP from texVEP. Results show a clear maturation of the processes underlying visual texture segregation in the full-term group, with a significant N2 latency reduction between 12 and 36 months of age for all conditions. Significant N2 amplitude reduction was observed for oriVEP between 12 and 24 months, as well as for texVEP between 12 and 24 months, and 12 and 36 months. Comparison between full-term and preterm children indicated significantly lower N2 amplitude for the preterm group at 12 months for oriVEP and texVEP. These differences were no longer apparent at 24 months of age, suggesting that children born preterm catch up with their full-term counterparts somewhere between 12 and 24 months of age. Our results appear to reflect a maturational delay in preterm children in both lower-level and higher-level visual processing during, at least, early childhood.

Highlights • Motion processing abilities develop gradually through childhood. • This lengthy development could be due to local noise and/or poor averaging. • 5–11-year-olds and adults performed equivalent noise and motion coherence tasks. • Through childhood, internal noise reduces and averaging increases. • Yet, only improved averaging explains developments in motion coherence sensitivity., The development of motion processing is a critical part of visual development, allowing children to interact with moving objects and navigate within a dynamic environment. However, global motion processing, which requires pooling motion information across space, develops late, reaching adult-like levels only by mid-to-late childhood. The reasons underlying this protracted development are not yet fully understood. In this study, we sought to determine whether the development of motion coherence sensitivity is limited by internal noise (i.e., imprecision in estimating the directions of individual elements) and/or global pooling across local estimates. To this end, we presented equivalent noise direction discrimination tasks and motion coherence tasks at both slow (1.5°/s) and fast (6°/s) speeds to children aged 5, 7, 9 and 11 years, and adults. We show that, as children get older, their levels of internal noise reduce, and they are able to average across more local motion estimates. Regression analyses indicated, however, that age-related improvements in coherent motion perception are driven solely by improvements in averaging and not by reductions in internal noise. Our results suggest that the development of coherent motion sensitivity is primarily limited by developmental changes within brain regions involved in integrating motion signals (e.g., MT/V5).

While the close link between eye movements and visual attention has often been demonstrated, recently distinct attentional modes have been associated with specific eye movement patterns. The ambient mode—serving the localization of objects and dominating early scene inspection—is expressed by short fixations and large saccade amplitudes. The focal mode—associated with the identification of object details and dominating later stages of scene exploration—is indicated by longer fixations embedded in short saccades. The relationship between these processing modes and eye movement characteristics has so far only been examined in adults. While studies in children revealed a maturation of oculomotor behavior up to adolescence, developmental aspects of the processing modes are still unknown. Here we explored these mechanisms by comparing eye movements during the inspection of naturalistic scenes. Therefore, gaze behavior from adults and children in four different age groups (2, 4–6, 6–8, 8–10 years old) was examined. We found a general effect of age, revealing that with age fixation durations decrease and saccade amplitudes increase. However, in all age groups fixations were shorter and saccades were longer at the beginning of scene inspection but fixations became longer and saccades became shorter over time. While saliency influenced eye guidance in the two youngest groups over the full inspection period, for the older groups this influence was found only at the beginning of scene inspection. The results reveal indications for ambient and focal processing strategies for as early as 2 years of age.

The typical development of motion perception is commonly assessed with tests of global motion integration using random dot kinematograms. There are discrepancies, however, with respect to when typically-developing children reach adult-like performance on this task, ranging from as early as 3years to as late as 12years. To address these discrepancies, the current study measured the effect of frame duration (Δt) and signal dot spatial offset (Δx) on motion coherence thresholds in adults and children. Two Δt values were used in combination with seven Δx values, for a range of speeds (0.3–38deg/s). Developmental comparisons showed that for the longer Δt, children performed as well as adults for larger Δx, and were immature for smaller Δx. When parameters were expressed as speed, there was a range of intermediate speeds (4–12deg/s) for which maturity was dependent on the values of Δx and Δt tested. These results resolve previous discrepancies by showing that motion sensitivity to a given speed may be mature, or not, depending on the underlying spatial and temporal properties of the motion stimulus.

Stereoscopic depth perception may be obtained from small retinal disparities that can be fused for single vision (fine stereopsis), but reliable depth information is also obtained from larger disparities that produce double vision (coarse stereopsis). While there is some evidence that stereoacuity improves with age, little is known about the development and maturation of coarse stereopsis. Here we address this gap by assessing the maturation of stereoscopic depth perception in children (4–14years) and adults over a large range of disparities from fused (fine) to diplopic (coarse). The observer’s task was to indicate whether a stereoscopic cartoon character was nearer or farther away than a zero-disparity reference frame. The test disparities were grouped into fine (0.02, 0.08, 0.17, 0.33, 0.68, 1.0deg) and coarse (2.0, 2.5, 3.0, 3.5deg) ranges based on an initial determination of the diplopia threshold for each observer. Next, percent correct depth direction was determined as a function of disparity. In the coarse range, accuracy decreased slightly with disparity and there were no differences as a function of age. In the fine range, accuracy was constant across all disparities in adults and increased with disparity in children of all ages. Performance was immature in all children at the finest disparity tested. We conclude that stereopsis in the coarse range is mature at 4years of age, but stereopsis in the fine range, at least for small disparities, continues to mature into the school-age years.

Previous research has indicated that the ability to integrate individual elements in the presence of noise is immature in 3-month-old infants. The present study extended the developmental timeline by investigating 6-month-olds’ ability to integrate individual elements into whole contours through an assessment of their capability to discriminate circle and square contours constructed from oriented Gabor patches via a newly designed cueing paradigm for infants. If infants discriminate the centrally-presented contour cues, then their eye movements would correctly anticipate subsequent target presentation at a rate greater than chance. The results indicated that infants integrated the contours and discriminated the different shapes, but, consistent with past research, this ability is still fairly immature at this age, tolerating limited amount of noise.

Higher visual functions were investigated in patients treated for bilateral congenital cataracts in two experiments. Participants were asked to detect either real or illusory contours (Kanizsa squares in Experiment 1 or one of four different Kanizsa contours in Experiment 2) among distractor items. Compared to normally sighted participants matched for age, gender and education, cataract patients treated after the age of 5–6 months took relatively longer to detect Kanizsa figures (Experiments 1 and 2) and they had higher miss rates (Experiment 2). The present results suggest that the ability of visual feature binding depends on early visual input and is permanently impaired if patterned vision is prevented in early infancy for 5 months or more.

Any object may contain at least two spatio-temporal components referred to as first- and second-order, respectively, defined by spatial-temporal luminance modulation or by contrast, texture or depth modulation. This study investigates form sensitivity of infants, normals, premature or strabismic. A two-alternative forced-choice preferential looking procedure was used in monocular and binocular condition. Maturation profile for both stimuli was similar in the control group. Strabismic infants showed a vertical offset in maturation, which affected the second-order more severely. The pre-term group showed a lag of second-order sensitivity. Our results underline differences between first- and second-order processing.

High-density EEG was used to investigate the cortical processing of a rotating visual pattern in 2-, 3-, and 5-month-old infants and in adults. Motion induced ERP in the parietal and the temporal–occipital border regions (OT) was elicited at all ages. The ERP was discernable in the 2-months-olds, significant and unilateral in the 3-month-olds and significantly bilateral in the 5-month-olds and adults. The motion induced ERP in the primary visual area was absent in the 2-month-olds and later than in the OT area for the 3-month-olds indicating that information to OT may be supplied by the V1 bypass at these ages. The results are in agreement with behavioural and psychophysical data in infants.

During the first 3 months, infants develop visual evoked potential (VEP) responses that are signatures of cortical orientation-selectivity and directional motion selectivity (Braddick, O. J., Wattam-Bell, J., & Atkinson, J. (1986). Orientation-specific cortical responses develop in early infancy. Nature, London, 320, 617-619; Wattam-Bell, J. (1991). Development of motion-specific cortical responses in infancy. Vision Research, 31, 287-297). This study compared these responses directly in the same infants, to investigate whether the later appearance of direction selectivity was intrinsic, or a function of the spatio-temporal characteristics of the stimuli used. Steady-state orientation-reversal (OR-) VEPs and direction-reversal (DR-) VEPs were recorded in infants aged 4-18 weeks. DR-VEPs were elicited with random pixel patterns and with gratings spatially similar to those used for OR-VEPs, at velocities of 5.5 and I I deg/s, and reversal rates of 2 and 4 reversals/s. Infants throughout the age range showed significant responses to orientation-reversal. Direction-reversal responses appeared in less than 25% of infants under 7 weeks of age, rising to 80% or more at 11-13 weeks, whether tested with dots or gratings and for both speeds and reversal rates. However, 2 reversals/s elicits the DR-VEP on average about 2 weeks earlier than 4 reversal/s stimulation. We conclude that human cortical direction selectivity develops separately from orientation-selectivity and emerges at a later age, even with tests that are designed to optimise the former. (c) 2005 Elsevier Ltd. All rights reserved.

We compared sensitivity to first-order versus second-order local motion in patients treated for dense central congenital cataracts in one or both eyes. Amplitude modulation thresholds were measured for discriminating the direction of motion of luminance-modulated (first-order) and contrast modulated (second-order) horizontal sine-wave gratings. Early visual deprivation, whether monocular or binocular, caused losses in sensitivity to both first- and second-order motion, with greater losses for second-order motion than for first-order motion. These findings are consistent with the hypothesis that the two types of motion are processed by different mechanisms and suggest that those mechanisms are differentially sensitive to early visual input.

We compared thresholds for discriminating changes in speed by 5-year-olds and adults for two reference speeds: 1.5 and 6 degrees s(-1). Both adults and 5-year-olds were more sensitive to changes from the faster than from the slower reference speed. Five-year-olds were less sensitive than adults at both reference speeds but significantly more immature at the slower (1.5 degrees s(-1)) than at the faster (6 degrees s(-1)) reference speed. The findings suggest that the mechanisms underlying speed discrimination are immature in 5-year-olds, especially those that process slower speeds.

We studied differences in the development of sensitivity to first-versus second-order global motion by comparing the motion coherence thresholds of 5-year-olds and adults tested at three speeds (1.5, 6, and 9 degrees s(-1)). We used Random Gabor Kinematograms (RGKs) formed with luminance-modulated (first-order) or contrast-modulated (second-order) concentric Gabor patterns with a sinusoidal spatial frequency of 3c deg(-1). To achieve equal visibility, modulation depth was set at 30% for first-order Gabors and at 100%, for second-order Gabors. Subjects were 24 adults and 24 5-year-olds. For both first- and second-order global motion, the motion coherence threshold of 5-year-olds was less mature for the slowest speed (1.5 degrees s(-1)) than for the two faster speeds (6 and 9 degrees s(-1)). In addition, at the slowest speed, the immaturity was greater for second-order than for first-order global motion. The findings suggest that the extrastriate mechanisms underlying the perception of global motion are different, at least in part, for first- versus second-order signals and for slower versus faster speeds. They also suggest that those separate mechanisms mature at different rates during middle childhood.

Despite the emerging scientific and clinical importance of measuring human contrast sensitivity (CS), developmental data are sparse, especially those obtained with a single methodology. We used a new, time-efficient, psychophysical card procedure to evaluate binocular CS in groups of 20 4- to 9-yr-olds and 10 adults. Combined with data from infants and toddlers obtained previously with the same method, our results show that CS is adult-like by 9 years of age. However, the pattern of development is asymmetrical across spatial frequency (SF): Sensitivity at high SF (which is very poor near birth) shows dramatic improvement over the first three years, but sensitivity at low SF shows much more gradual development, a result which may be explained by differences in the maturation of the underlying neural SF channels. Also notable is that the method shows clinical potential due to its relative speed, ease of use, and consistent results across such a broad age range.

To compare the effects of early monocular versus early binocular deprivation on the perception of global form, we assessed sensitivity to global concentric structure in Glass patterns with varying ratios of paired signal dots to noise dots. Children who had been deprived by dense congenital cataracts in one (n=10) or both (n=8) eyes performed significantly worse than comparably aged children without eye problems. Consistent with previous results on sensitivity to global motion [Vision Research 42 (2002) 169], thresholds in the deprived eyes were significantly better after monocular deprivation than after binocular deprivation of comparable duration, even when there had been little patching of the nondeprived eye after monocular deprivation. Together, the results indicate that the competitive interactions between a deprived and nondeprived eye evident in the primary visual cortex can co-occur with complementary interactions in extrastriate cortex that enable a relative sparing of some visual functions after early monocular deprivation.

The present experiment uses a quadrature motion paradigm to investigate the motion correspondence cues used by young infants for coding the direction of motion of red:green isoluminant gratings. Three-month-old infants and adults were tested with 0.25 c:d luminance-modulated or red:green isoluminant gratings, either moving continuously or shifted in spatial quadrature. Both direction-of-motion and detection thresholds were measured, and motion:detection (M:D) threshold ratios were examined. Infants, like adults, could code the direction of motion of red:green quadrature-shifted gratings. In adults, M:D ratios were similar for continuous and quadrature motion. In infants, M:D ratios were higher for quadrature than for continuous motion, but elevations of similar magnitude were seen for both luminance-modulated and red:green gratings. The results suggest that frequency-doubled signals, such as those often seen in the magnocellular (M-cell) pathway, are not necessary for coding the direction of motion of isoluminant gratings in infant subjects. Two other theoretical options—mediation by the scatter of isoluminance points in the M-cell population, and parvocellular (P-cell) mediation—are discussed. © 1999 Elsevier Science Ltd. All rights reserved.

The present paper constitutes a review of the literature on young infants’ chromatic discrimination capabilities. A series of early studies showed that infants as young as two months postnatal can make at least some chromatic discriminations between stationary, homogeneous fields of different wavelength compositions. Current studies of spatial and temporal contrast sensitivity functions (CSFs) for red/green isoluminant stimuli suggest that spatial chromatic CSFs show developmental changes in sensitivity and spatial scale, but not curve shape; while temporal chromatic CSFs (tCSFs) show developmental changes in sensitivity and curve shape, but not temporal scale. Infants can also code the direction of motion of moving isoluminant red/green gratings, for both continuous and quadrature motion. The possible mechanisms that underlie infants’ chromatic discriminations are discussed.

Swept-contrast visual evoked potential (VEP) techniques were used to measure the development of contrast sensitivity functions (CSFs) for achromatic and red/green isoluminant chromatic gratings. Subjects were infants of 8, 14, 20 and 32 weeks of age, and adults. Stimuli were 20 deg, 0.3–4 cyc/deg sinusoidal gratings, counterphased at 6 Hz and modulated through white. Achromatic and chromatic CSFs for all ages could be fit simultaneously with a double exponential equation of a common, lowpass shape. Both achromatic and chromatic CSFs exhibited developmental shifts in both sensitivity and spatial scale. From 8 weeks to adulthood, sensitivity increased by 0.64 log units for achromatic gratings and by 0.91 log units for chromatic gratings, yielding an 0.27 log unit larger sensitivity change for chromatic than for achromatic stimuli. Spatial scale shifts were closely similar across achromatic and chromatic CSFs, and were consistent with the factor of about four predicted on the basis of changes in foveal receptor packing density and eye size. The question of uniform vs differential loss of sensitivity for chromatic vs achromatic stimuli at fixed spatial frequencies is discussed.

In order to assess the relative contributions of chromatic vs luminance information to motion processing in infants, we employed a motion:detection (M:D) paradigm. Stimuli consisted of 27 deg by 40 deg, 0.25 c/deg sinusoidal gratings moving at 22 deg/sec (5.6 Hz), and were either chromatically defined or luminance-defined. Contrast thresholds for direction-of-motion (M) were obtained using a directional eye movement technique. Contrast thresholds for detection (D) were obtained using forced-choice preferential looking. M:D threshold ratios were obtained for individual infant subjects, and results were compared to those of adults.As expected, adult M:D threshold ratios were near 1:1 for luminance-defined stimuli, but greater than 1:1 for chromatically defined stimuli. This suggests that, for adults, luminance-defined, but not chromatically defined, stimuli are detected by mechanisms labeled for direction of motion. By contrast, infant M:D ratios for chromatically and luminance-defined stimuli were approximately equal and close to 1:1, suggesting that, for infants, luminance- as well as chromatically defined stimuli are detected by mechanisms that are labeled for direction of motion. Copyright © 1996 Elsevier Science Ltd.

The ability of infants to discriminate between opposite directions of motion was assessed using forced-choice preferential looking between a random-dot pattern which was segregated into regions which moved in opposite directions, and a uniform pattern in which all the dots moved in the same direction. The first experiment measured velocity thresholds ( νmin and νmax) for direction discrimination; between 10 and 13 weeks νmin decreased, while at the same time νmax increased. The second experiment explored possible implications of this expanding velocity range for direction discrimination by younger infants. One-month-olds showed no evidence for direction discrimination at any of a number of test velocities in the range 1–43 deg/sec. The 1-month-olds were also tested with two additional conditions: they could discriminate between moving and static patterns at velocities of 10 deg/sec or above, and they could also discriminate between coherent and incoherent motion at velocities of 21 deg/sec or below. Neither of these discriminations depends on sensitivity to the direction of the coherent motion. The results suggest that 1-month-olds may not be sensitive to the direction of visual motion.

Quantitative data on the early morphological development of the human retina show that the peripheral region is relatively more mature than the central region. These results have stimulated researchers to compare the development of visual functions in the central and peripheral regions of the visual field. Here, we used preferential looking to evaluate 1-, 2- and 3-month-old infants' central and peripheral (10 degrees and 30 degrees) monocular visual acuity. There were three findings: (i) both central and peripheral acuities were poor at 1 month, improved over the age range tested, but were still about 3 octaves worse than adults' acuity; (ii) at all ages monocular acuity decreased with increasing eccentricity; (iii) 2- and 3-month-olds showed higher acuity for gratings in the temporal than in the nasal visual field at 30 degrees. The implications of these results for issues in visual development are discussed.

Four-week-olds, 9-week-olds, and adult subjects were tested with low spatial frequency sinusoidal gratings moving at a speed of 25 deg/sec. Luminance-modulated and red/green gratings were presented either separately, or superimposed and moving in opposite directions in a chromatic motion nulling paradigm. An adult observer judged the direction of the slow phase of the subject's eye movements. Luminance-modulated gratings elicited directionally appropriate eye movements in all three age groups, with contrast thresholds decreasing markedly with age. For red/green gratings alone, 4-week-olds responded only marginally, but 9-week-olds and adults produced consistent directionally appropriate eye movements. In the motion nulling condition, 15 % contrast luminance-modulated gratings were about equally effective in nulling the motion of the red/green gratings in all three age groups. A formal model of the motion nulling paradigm, separating threshold and equivalent luminance contrast parameters, was developed and applied to the data. Model fits showed that equivalent luminance contrast was constant or nearly constant across age groups. This outcome is consistent with the hypothesis that, with respect to adults, infants show a uniform rather than a differential loss of sensitivity to moving red/green vs luminance-modulated stimuli.

We measured discrimination threshold for time to contact with a simulated approaching object at 20 locations between 0 and 32 deg eccentricity in the left, right, upper, and lower visual fields. We also measured discrimination threshold for rate of expansion at the same 20 locations. At 0 deg eccentricity, discrimination of trial-to-trial variations in time to contact was virtually unaffected by simultaneous trial-to-trial variations of both rate of expansion and starting size, discrimination of trial-to-trial variations in rate of expansion was virtually unaffected by simultaneous trial-to-trial variations of both time to contact and starting size, and discrimination of trial-to-trial variations in starting size was virtually unaffected by simultaneous trial-to-trial variations of both time to contact and rate of expansion. We conclude that, in foveal vision, time to contact, rate of expansion and size can be processed simultaneously, independently and in parallel. Our main finding was that this independence progressively decreased as eccentricity increased. For example, in peripheral, but not in foveal vision, variations in rate of expansion produced illusory variations in time to contact. A secondary finding was that the effect of eccentricity on discrimination threshold for the task-relevant variable (whether time to contact or rate of expansion) was considerably less than the effect of eccentricity on visual acuity and on several other aspects of visual performance. We suggest that visual processing of time to contact is developed by exposure to optic flow patterns created by self-locomotion.

Visually guided saccades to single targets undershoot by about 10% of the target distance, and require additional secondary saccades to foveate the target. We examine theoretically the hypothesis that undershooting is an economical strategy for maximizing the time for clear vision by minimizing saccadic flight-time. Using a simple stochastic model, Monte-Carlo simulations show that when the standard deviation of saccadic error is about 10% of the target distance the optimal gain of primary saccades is about 0.93–0.97 depending on the main sequence for saccade duration. When the standard deviation of saccadic error is large, as occurs in the human infant, the optimal gain decreases to about 0.6, which agrees with empirical observations. We conclude that saccadic undershoot is consistent with an adaptive controller that attempts to minimize total saccadic flight-time during sequences, rather than retinal error. The ethology and physiology of such a controller is discussed in the context of visual scanning and visual development.