The role of structure in infant visual pattern perception.

In Exp 1, 15 infants (aged 4 mo 2 days to 5 mo 9 days) were presented with a symmetrical (SYP) and an asymmetrical pattern (ASP), using a paired comparison preference technique. The SYPs represented vertical, horizontal, 2-fold, and 4-fold symmetry (SYM). 15 infants (aged 3 mo 29 days, to 5 mo 16 days) in Exp 2 additionally viewed patterns with 8-fold SYM, using the same procedure as Exp 1. Ss preferred patterns with multiple axes of bilateral SYM relative to ASPs. Also, vertically oriented single axis bilateral SYM was more salient than horizontally oriented SYM. The perception of structure appears to be basic to the functioning of the visual system. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination and memory for symmetry in young children.

Conducted 3 experiments to assess the development of symmetry perception in children between the ages of 4 and 6 yrs. Exp I employed a learning task in which 72 Ss were asked at different times to discriminate vertically symmetrical, obliquely symmetrical, and horizontally symmetrical holistic patterns from asymmetrical ones. Results reveal a developmental progression: 4-yr-olds discriminated only vertical; 5-yr-olds, vertical and horizontal; and 6-yr-olds, vertical, horizontal, and oblique. Exp II retested the 18 6-yr-olds with fragmented patterns of the different symmetries; these Ss regressed to the performance level of 4-yr-olds and only discriminated vertical. Exp III, conducted with 18 Ss, used a memory-production task with new vertical, oblique, horizontal, and asymmetrical patterns constructed to 4, 5, or 6 elements. Measures of the goodness and accuracy of Ss' reproductions were consistent with data from the discrimination-learning experiments in terms of age, stimulus orientation, and stimulus complexity. These studies support the view that vertical symmetry is special perceptually and developmentally and that, after vertical, horizontal predominates, followed by oblique. The role of symmetry in early perceptual development and the value of child–adult perceptual comparisons are discussed. (55 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The salience of vertical symmetry

It has long been accepted that amongst patterns which are bilaterally symmetrical, those which have their axis of symmetry vertical are more saliently symmetrical than patterns whose axis of symmetry is at some other orientation. The evidence regarding the relative salience of other orientations of axis of symmetry is somewhat more equivocal. In experiment 1, subjects were required to discriminate between symmetric or random-dot patterns when the axis of symmetry was at one of eighteen different orientations, spaced 10 degrees apart, both clockwise and counterclockwise of vertical to horizontal. The data indicated that vertical was most salient, then horizontal but that, unlike in the classical oblique effect for contrast sensitivity, performance for precisely diagonal axes was better than that for surrounding axis orientations. Additional data (from experiments 2 and 3) also showed that the salience of vertical and horizontal axes of symmetry can be manipulated extensively by varying the range of stimuli presented, presumably by manipulating the scanning or attentional strategy adopted by the observer. Many previous studies of symmetry perception may have confounded hard-wired salience for vertical symmetry with scanning or attentional strategies.     

Facial asymmetry and attractiveness judgement in developmental perspective.

This study examined the role of facial symmetry in the judgment of physical attractiveness. Four experiments investigated people's preference for either somewhat asymmetrical portraits or their symmetrical chimeric composites when presented simultaneously. Experiment 1 found a higher selection rate for symmetrical faces with neutral expression for portraits of old people, and Experiment 2 indicated this may be because symmetry serves as cue for youth in old age. In Experiments 3 and 4 participants examined portraits with emotional expressions. Experiment 3 found a higher selection rate for asymmetrical faces, and Experiment 4 indicated this may be because observers perceived them as more genuine and natural. This study suggests that the low degree of facial asymmetry found in normal people does not affect attractiveness ratings (except for old age), probably because observers are not tuned to perceive it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fluctuations in unimanual hand preference in infants following the onset of duplicated syllable babbling.

22 infants were tested for unimanual handedness at weekly intervals for a 14-wk period beginning with the week of duplicated syllable babbling onset at ages 4.9–8.8 mo. Ss showed a right-handed preference on the 1st session. Analyses based on Ss' preferred hand on the 1st session (17 right-handers, 5 left-handers) indicate 2 fluctuations in the unimanual hand preference following babbling onset, with troughs in preferred hand performance occurring 4 and 8 wks after babbling onset. Group analyses indicating effects of sex and/or birth order on these fluctuations, and inspection of the data for individual Ss suggested considerable variability across Ss in the occurrence and/or timing of these fluctuations. Nevertheless, findings support A. Gesell's (1954) claim that hand preference in infancy alternates between right-handedness and ambilaterality, and they suggest underlying change in hemispheric specialization or asymmetrical brain organization for motoric control. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The detection of bilateral symmetry: Effects of surrounding frames.

Examined whether the detection of bilateral symmetry in the fronto-parallel plane is influenced by surrounding frames. The study was conducted with 12 Ss. When obliquely or vertically oriented rectangular frames were presented simultaneously surrounding the dot patterns, the frames influenced symmetry detection. Vertical symmetry detection was slower in the tilted frame than it was in the vertical frame, and tilted symmetry was detected faster in the tilted frame than it was in the vertical. When there was a time delay between frame and pattern onset, there was no measurable frame effect. Symmetry detection was slowed when not in line with the long axis of the frame, whereas symmetry detection was not affected when the frame axis was aligned with the symmetry axis. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Complexity in object manipulation by Japanese macaques (Macaca fuscata): A cross-sectional analysis of manual coordination in stone handling patterns.

Defined as a spontaneous stone-directed noninstrumental manipulative behavior, and comprised of multiple one-handed and (a)symmetrical/(un)coordinated two-handed patterns, stone handling (SH) is a good candidate for the study of complexity in object manipulation. We present a cross-sectional developmental analysis of SH complexity in Japanese macaques (Macaca fuscata), through the combined investigation of bimanuality, coordination, and symmetry in hand use. Bimanual SH patterns were more frequent than unimanual patterns. Among bimanual patterns, coordinated actions were more frequent than uncoordinated ones. We recorded five asymmetrical coordinated SH patterns with manual role differentiation, a form of hand use reminiscent of complex actions involving the use of tools in monkeys and apes. Bimanuality in SH was affected by body posture. Aging individuals performed less bimanual and less coordinated SH patterns than younger individuals. Our result on senescent males performing less bimanual patterns than senescent females was consistent with sex differences found in the late deterioration of complex manual movements in other species. Although some SH patterns represent a high degree of behavioral complexity, our results suggest that SH behavior is not as complex as tool-use or tool-manufacture in other nonhuman primates and hominids. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Preference for symmetry is experience dependent in newborn chicks (Gallus gallus).

Spontaneous pecking preferences toward symmetric or asymmetric stimuli were tested in newborn chicks (Gallus gallus). A preference for asymmetric patterns was found in na?ve chicks (either 24 or 48 hours old), although a preference for symmetry appeared at retest after chicks had experienced standard rearing conditions (Experiments 1 and 2). Only food-experienced chicks preferred symmetric patterns; food-deprived and hand-fed chicks did not show any preference (Experiment 3). A key factor that allowed for the emergence of a preference for symmetry may relate to the improving of pecking sensorimotor skills occurring during active food manipulation. Possible explanations are discussed for the late emergence of the preference for symmetry and for the preference for asymmetry found in na?ve chicks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Graft decentration in penetrating keratoplasty: nonmechanical trephination with the excimer laser (193 nm) versus the motor trephine

Seven right-handed participants performed bimanual circling movements in either a symmetrical or an asymmetrical coordination mode. Movements were paced with an auditory metronome at predetermined frequencies corresponding to transition frequency, where asymmetrical patterns became unstable, or at two-thirds transition frequency where both symmetrical and asymmetrical patterns were stable. The pacing tones were presented in either a high (1000 Hz) or low (500 Hz) pitch, and the percentage of high-pitched tones during a 20 s trial varied between 0% and 70%. Participants were instructed to count the number of high-pitched pacing tones that occurred during a trial of bimanual circling. Overall, the symmetrical pattern was more stable than the asymmetrical pattern at both frequencies. Errors on the tone-counting task were significantly higher during asymmetrical circling than symmetrical circling but only at the transition movement frequency. The results suggest that cognitive processes play a role in maintaining coordination patterns within regions of instability.     

Hand coordination in bimanual circle drawing.

Two right-handed and 2 left-handed participants drew circles in the horizontal plane with both hands simultaneously in either a symmetrical or an asymmetrical mode, at their preferred rate or as fast as possible. During symmetrical movements, the hands showed frequency and phase synchronization at both rates. During fast asymmetrical movements, the hands showed increased phase difference and phase variability, as well as transitions to symmetrical movements, and cases of frequency decoupling. Large distortions of the hand trajectory were also observed under fast asymmetrical movements. Trajectory distortions and movement direction reversals were confined to the nondominant hand. Under the assumption that circular trajectories are generated by properly timed orthogonal oscillations along the y-axis and the x-axis, these findings are accounted for by the characteristics of coupling between homologous functional oscillators of the 2 body sides. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Association of vitamin K-dependent coagulation proteins and C4b binding protein with triglyceride-rich lipoproteins of human plasma

It has been proposed that females use the symmetry of secondary sexual traits to differentiate between potential mates. The vertical bars on male swordtail fish function as a signal that attracts females and deters rival males in one swordtail species. In addition, male courtship behaviour of most Xiphophorus species incorporates serial lateral presentations, which provide females with a clear opportunity to assess males for bilateral symmetry. We tested the hypothesis that X. cortezi females prefer males with a symmetrical bar number by determining whether females switched their preference between two males when we switched which male had a symmetrical number of bars. The ability to manipulate the bars without influencing other male traits allowed us to control for male characters correlated with bar symmetry that females might prefer. The degree of asymmetry in bar number we used was within the degree of asymmetry found for this trait in nature. Females switched their preference between a pair of males when we switched which male was symmetrical for bar number. We discuss the possibility that females prefer a symmetrical bar number as well as an alternative hypothesis. Copyright 1998 The Association for the Study of Animal Behaviour.     

Infants prefer the musical meter of their own culture: A cross-cultural comparison.

Infants prefer native structures such as familiar faces and languages. Music is a universal human activity containing structures that vary cross-culturally. For example, Western music has temporally regular metric structures, whereas music of the Balkans (e.g., Bulgaria, Macedonia, Turkey) can have both regular and irregular structures. We presented 4- to 8-month-old American and Turkish infants with contrasting melodies to determine whether cultural background would influence their preferences for musical meter. In Experiment 1, American infants preferred Western over Balkan meter, whereas Turkish infants, who were familiar with both Western and Balkan meters, exhibited no preference. Experiments 2 and 3 presented infants with either a Western or Balkan meter paired with an arbitrary rhythm with complex ratios not common to any musical culture. Both Turkish and American infants preferred Western and Balkan meter to an arbitrary meter. Infants’ musical preferences appear to be driven by culture-specific experience and a culture-general preference for simplicity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual experience influences 12-month-old infants' perception of goal-directed actions of others.

In the present study, we investigated whether infants' own visual experiences affected their perception of the visual status of others engaging in goal-directed actions. In Experiment 1, infants viewed video clips of successful and failed goal-directed actions performed by a blindfolded adult, with half the infants having previously experienced being blindfolded. The results showed that 12-month-old infants who were previously blindfolded preferred to look longer at the demonstrator's successful actions, whereas no such preference was observed in 8-month-old infants. In Experiment 2, infants watched the same 2 actions when the adult demonstrator was not blindfolded. The responses of 12-month-old infants were the opposite of those observed in Experiment 1: They showed a preference for the failed actions. These findings suggest that previous experience influenced the subsequent perception of others' goal-directed actions in the 12-month-old infants. We favor the interpretation that the preference for the successful actions in the 12-months-old infants provided with blindfolded experience demonstrates the influence of perceptual experience on considering the visual status of others engaging in goal-directed actions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Stability and Transitions in Mother-Infant Face-to-Face Communication During the First 6 Months: A Microhistorical Approach.

In this study the authors attempted to unravel the relational, dynamical, and historical nature of mother-infant communication during the first 6 months. Thirteen mothers and their infants were videotaped weekly from 4 to 24 weeks during face-to-face interactions. Three distinct patterns of mother-infant communication were identified: symmetrical, asymmetrical, and unilateral. Guided by a dynamic systems perspective, the authors explored the stability of and transitions between these communication patterns. Findings from event history analysis showed that (a) there are regularly recurring dyadic communication patterns in early infancy, (b) these recurring patterns show differential stabilities and likelihoods of transitions, (c) dynamic stability in dyadic communication is shaped not only by individual characteristics (e.g., infant sex and maternal parity) but also by the dyad's communication history, and (d) depending on their recency, communication histories varying in temporal proximity exert differential effects on the self-organization processes of a dyadic system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetrical vertical phorias indicating dissociated vertical deviation in subjects with normal binocular vision

We measured the symmetry of phoria angles in six normal subjects. Subjects were selected on the basis of good visual acuity and stereopsis, normal binocular eye alignment and, apart from mild refraction errors, absence of ocular abnormalities. They were instructed to look at a word on a reading chart at 2 m distance. Each measurement consisted of five subsequent intervals of 5 s duration. During these five intervals viewing was binocular, with the right eye only, binocular, with the left eye only, and binocular, respectively. Each experiment consisted of twelve measurements. Eye movements were measured with scleral coils suited for measuring in horizontal, vertical and torsional directions. Five out of six subjects displayed an asymmetrical vertical phoria; one subject showed an alternating hyperphoria; four displayed a left over right vertical phoria that was largest for left eye occlusion. Only one subject showed a symmetrical vertical phoria. Both the size of the vertical phorias and the size of the asymmetries in these vertical phorias were very small: on average 0.16 +/- 0.01 and 0.17 +/- 0.01 degree, respectively. The direction of the vertical phoria asymmetries (the largest left over right was found with left eye occlusion) and the fact that asymmetries were found more often in vertical than horizontal and torsional phorias suggest that these asymmetries are related to dissociated vertical deviation. These results suggest that dissociated vertical deviation, often observed in subjects with a disruption of binocular vision early in life, reflects the enhancement of a phenomenon that is present in normal subjects as well.     

Salt preference and development.

This article reviews work with infants and young animals to examine a number of developmental questions regarding salt preference. Included is a discussion of evidence related to whether human infants display a salt preference, whether there are developmental changes in preferred level of saltiness, and whether early experience with salted foods or drinks plays a role in shaping adult salt preference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The balance of employment and motherhood: Longitudinal study of mothers' feelings about separation from their first-born infants.

Examined how older, college-educated White mothers' preference to be employed or to remain home with their infants affected the development of their anxiety about separation from their infants over the 1st 13? mo of motherhood. On measures of anxiety about separation, career salience, and maternal role investment, 26 mothers (mean age 27.38 yrs) who preferred employment were compared with 36 mothers (mean age 27.89 yrs) who preferred to stay at home. Measures were taken at 2 days, 7 wks, 8 mo, and 13? mo postpartum. Employment-preference mothers' anxiety about separation declined earlier and to a greater extent than that of home-preference mothers, who were more strongly invested in the maternal role but less committed to jobs or careers. Discussion centers on the importance of employment preference as opposed to actual employment status for understanding how women balance career and motherhood. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of lateralized components of feeding behavior in the ring-tailed lemur (Lemur catta).

Twenty-one ring-tailed lemurs (Lemur catta) were videotaped during feeding. They had previously been classified as left-, right- or ambipreferent on the basis of the hand used to reach for food. The feeding sequences provided duration-based measures of manipulation, hand and mouth lateralization, and posture during feeding sequences with 2 types of food. Hand preference for reaching and holding was stable over time and across measurement conditions. As a group, the lemurs grasped fruit bimanually more often than chow; however, right- and ambipreferent lemurs spent more time holding food bimanually than did left-preferent ones. Older animals consumed chow more quickly than did younger animals but did not differ in their rate of manipulation. Lemurs had a preference for using one side of the mouth in feeding, but this had no directional relation to preferred hand. Three postural feeding patterns were identified. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parasitic infections in villagers from three districts of the Brazilian Amazon

Past studies on bimanual coordination have revealed a general preference to move the limbs in a symmetrical fashion, also denoted as the in-phase mode. Its counterpart, the asymmetrical or anti-phase mode, is performed with lower degrees of accuracy and stability. This ubiquitous tendency to activate the homologous muscle groups is referred to as the muscle grouping constraint (egocentric constraint). The present study confirmed the generalizability of this constraint across various coordination patterns, performed in the horizontal plane. In addition, evidence was generated that movement direction in extrinsic space also constrains bimanual coordination (allocentric constraint). Overall, the present observations suggest that direction is an important movement parameter that is encoded in the central nervous system and that is subject to interactions between the neural specifications of both limbs.     

The threshold for immune cell reactivity to milk antigens decreases in cow's milk allergy with intestinal symptoms

BACKGROUND: In cow's milk allergy (CMA) with intestinal symptoms, peripheral blood mononuclear cells (PBMCs) secrete tumor necrosis factor-alpha (TNF-alpha), altering intestinal function. However, the type of cow's milk protein (CMP) that triggers symptoms (intact or intestinally processed) is not known, and neither is the minimal amount required. METHODS: PBMCs were isolated from infants with active CMA or cured infants just before a new challenge and stimulated with intact or intestinally processed CMP. Supernatants were tested for cytokine content and for their ability to perturb intestinal barrier capacity, measured in Using chambers in HT29-19A intestinal cells. RESULTS: PBMCs from infants with active CMA secreted more TNF-alpha, when they were stimulated with intact rather than intestinally processed CMPs, and more TNF-alpha than PBMCs from cured infants. Accordingly, supernatants from PBMCs stimulated with intact but not intestinally processed CMPs significantly increased intestinal permeability. The CMP concentration required to trigger TNF-alpha secretion capable of altering intestinal function was very small in infants with active CMA (approximately 2 micrograms/ml), but about 300 times higher in cured infants. CONCLUSION: Intact rather than intestinally processed proteins stimulate PBMCs to release TNF-alpha and alter intestinal barrier capacity. The threshold for PBMC reactivity to milk antigens drops considerably during active CMA with intestinal symptoms.