Preference for biological motion in domestic chicks: sex-dependent effect of early visual experience

To examine the effects of early visual experience on preference for biological motion (BM), newly hatched chicks were exposed to a point-light animation (a visual stimulus composed of identical light points) depicting the following features of a hen: a walking hen (a BM stimulus), a rotating hen (a non-BM stimulus), a pendulum stimulus, a random motion stimulus and a stationary pattern. Chicks were then tested in a binary choice task, choosing between walking-hen and rotating-hen stimuli. Males exhibited a preference for BM if they had been trained with any animation except the stationary pattern stimulus, suggesting that the BM preference was not learned, but induced by motion stimuli. We found a significant positive correlation between the number of approaches in training and the preference in the test, but locomotion alone did not cause preference for BM. In contrast, females exhibited a particularly strong preference for walking-hen stimuli, but only when they had been trained with it. Furthermore, females (but not males) trained with random motion showed a preference for walking hen over walking cat (a biological motion animation depicting a cat), possibly suggesting that females are choosier than males. Chicks trained with a stationary pattern and untrained controls did not show a significant preference. The induction of BM preference is discussed in terms of possible ecological background of the sex differences.     

Early visual experience influences behavioral lateralization in the guppy

Individual differences in lateralization of cognitive functions characterize both humans and non-human species. Genetic factors can account for only a fraction of the variance observed and the source of individual variation in laterality remains in large part elusive. Various environmental factors have been suggested to modulate the development of lateralization, including asymmetrical stimulation of the sensory system during ontogeny. In this study, we raised newborn guppies in an asymmetric environment to test the hypothesis that early left–right asymmetries in visual input may affect the development of cerebral asymmetries. Each fish was raised in an impoverished environment but could voluntarily observe a complex scene in a nearby compartment containing a group of conspecifics. Using asymmetric structures, we allowed some subjects to observe the complex scene with the right eye, others with the left eye, and control fish with both eyes. Among asymmetrically stimulated fish, the mirror test revealed eye dominance congruent with the direction of asymmetric stimulation, while controls showed no left–right laterality bias. Interestingly, asymmetric exposure to social stimuli also affected another aspect of visual lateralization—eye preference for scrutinizing a potential predator—but did not influence a measure of motor asymmetry. As the natural environment of guppies is fundamentally asymmetrical, we suggest that unequal left–right stimulation is a common occurrence in developing guppies and may represent a primary source of individual variation in lateralization as well as an efficient mechanism for producing laterality phenotypes that are adapted to local environmental conditions.     

The influence of visual experience on visual and spatial imagery

Differences are reported between blind and sighted participants on a visual-imagery and a spatial-imagery task, but not on an auditory-imagery task. For the visual-imagery task, participants had to compare object forms on the basis of a (verbally presented) object name. In the spatial-imagery task, they had to compare angular differences on the basis of the position of clock hands on two clock faces, again only on the basis of verbally presented clock times. Interestingly, there was a difference between early-blind and late-blind participants on the visual-imagery and the spatial-imagery tasks: late-blind participants made more errors than sighted people on the visual-imagery task, while early-blind participants made more errors than sighted people on the spatial-imagery task. This difference suggests that, for visual (form) imagery, people use the channel currently available (haptic for the blind; visual for the sighted). For the spatial-imagery task in this study reliance on haptic processing did not seem to suffice, and people benefited from visual experience and ability. However, the difference on the spatial-imagery task between early-blind and sighted people in this study might also be caused by differences in experience with the analogue clock faces that formed the basis for the spatial judgments.     

Origins of the proprioceptive function of vision: visual control of posture in one day old domestic chicks.

Recently hatched domestic chicks control their upright bipedal posture, at least in part, with respect to the flow of visual information at the retina, as do human infants when they first acquire control of the head, of sitting, and of standing. Some implications of the similarity of the proprioceptive function of vision in chicks and in humans for the origins and development of postural control are discussed.     

Enhanced prenatal auditory experience facilitates species-specific visual responsiveness in bobwhite quail chicks (Colinus virginianus)

Premature stimulation of a later developing sensory system is known to impact the functioning of earlier developing sensory systems. For example, exposure to premature (prenatal) visual experience results in a decline in species-typical auditory responsiveness in several precocial bird species. The present study examined the influence of experiential enhancement of an earlier developing sensory system on a later developing modality. Specifically, the influence of enhanced prenatal auditory stimulation on subsequent postnatal auditory and visual functioning of bobwhite quail (Colinus virginianus) chicks was assessed. Results indicate that birds receiving exposure to increased amounts of unaltered, species-typical embryonic vocalizations before hatching show species-typical auditory responsiveness at both 12 hr and 24 hr after hatching, but exhibit an accelerated pattern of species-typical visual responsiveness by 24 hr of age. These findings suggest that enhancement of an earlier developing sensory system can facilitate the development of a later developing sensory system and serve to demonstrate the dynamic nature of early perceptual organization.     

Short- and long-term behavioral effects of neonatal exposure to bombesin.

Subcutaneous (sc) administration of the tetradecapeptide bombesin (BN) (1-10 mg/kg) elicited grooming in rat pups of 1-10 days of age and the magnitude of this response decreased as a function of age. The form of grooming induced was qualitatively different from that seen following central injection of BN to adult rats. Subchronic neonatal exposure to BN (5 or 10 mg/kg; sc, twice daily for the first 8 postnatal days) had no effect on subsequent adult behavior displayed under mildly stressful or novel conditions, in the open field or in an elevated plus maze. However, both saline and the high dose of BN (10 mg/kg) pretreatments increased adult sensitivity to central BN (0.1 micrograms; icv) as compared to noninjected but neonatally handled controls or those rats neonatally pretreated with the lower dose of BN (5 mg/kg). This was best demonstrated by increases in scratching activity at the 0.1-micrograms dose of icv BN. Neonatal pretreatments had no effect on later adult sensitivity to BN injected intraperitoneally (ip). These data indicate that BN receptors in the rat central nervous system are pharmacologically functional from an early stage in ontogeny. Systems utilizing BN-like peptides are, to a degree, plastic early in ontogeny and altered adult sensitivity to BN icv can be achieved via subchronic exposure to BN during infancy. Endogenous BN-based mechanisms did not appear to play a role in the development and/or expression of behavior(s) elicited under mildly stressful or novel conditions.     

The effect of interpolated experience on visual recognition

Two hundred twelve-year-old children were shown a circle-with-gap figure and, five minutes later, required to recognize this figure from among a graded series of similar figures. The interpolation of circles with different sizes of gap resulted in retroactive interference, the recognition error being either positive or negative according to the nature of the interpolated figures. The results also draw attention to the dependence of certain recognition errors on the age of the subject and indicate a developmental trend in the perceiving and recognizing of simple figures.     

Consistency of aggressive temperament in domestic pigs: The effects of social experience and social disruption

Resident‐intruder (R‐I) tests can be used to measure the aggressive temperament of domestic pigs (Sus scrofa), and have previously been shown to predict the severity and persistence of aggression when unfamiliar pigs are mixed. To study the consistency of individual differences in aggressiveness over time, 112 pigs (eight from each of fourteen litters) were given two R‐I tests at each of three ages (46, 80, and 113 days). Pigs were R‐I tested singly in an arena within the home pen, where a smaller unfamiliar intruder pig was introduced to a resident pig. Latency to the first attack by the resident was recorded, and the test was stopped as soon as an attack occurred, otherwise the test lasted five minutes. Pigs from eight of the litters used here had been allowed to mix with another litter prior to weaning (days 10–30; socialised), while pigs in six litters remained in littermate groups (control). To determine whether consistency would survive the effects of social disruption, pigs were mixed into new groups on two occasions between the first and second test, then remained in these groups until the third test. Evidence of consistency was found, despite the social disruption. Socialised pigs were more aggressive than controls, females were more aggressive than males, and certain litters were more aggressive than others. After adjusting for these, consistent differences between individuals were still evident. Consistency was higher between the second and third tests compared to the first and second, possibly because of stable group membership or the effects of age or experience. In support of the idea that social experience improves consistency, socialised pigs were more consistent than controls throughout. Evidence of consistent individual differences in aggressive temperament suggests that breeding or changes to early life experiences could have a long‐lasting influence on aggressive behaviour in pigs. Aggr. Behav. 30:435–448, 2004. © 2004 Wiley‐Liss, Inc.     

Spontaneous generalization of abstract multimodal patterns in young domestic chicks

From the early stages of life, learning the regularities associated with specific objects is crucial for making sense of experiences. Through filial imprinting, young precocial birds quickly learn the features of their social partners by mere exposure. It is not clear though to what extent chicks can extract abstract patterns of the visual and acoustic stimuli present in the imprinting object, and how they combine them. To investigate this issue, we exposed chicks (Gallus gallus) to three days of visual and acoustic imprinting, using either patterns with two identical items or patterns with two different items, presented visually, acoustically or in both modalities. Next, chicks were given a choice between the familiar and the unfamiliar pattern, present in either the multimodal, visual or acoustic modality. The responses to the novel stimuli were affected by their imprinting experience, and the effect was stronger for chicks imprinted with multimodal patterns than for the other groups. Interestingly, males and females adopted a different strategy, with males more attracted by unfamiliar patterns and females more attracted by familiar patterns. Our data show that chicks can generalize abstract patterns by mere exposure through filial imprinting and that multimodal stimulation is more effective than unimodal stimulation for pattern learning.