Visual exploration of reaching space during left and right arm movements in 6-month-old infants

Infant's manual laterality and eye-hand coordination emerge during the second part of the first year of life with the development of reaching. Nevertheless, little is known about the potential asymmetric characteristics of this coordination. The aim of this study was to describe visuo-spatial exploration in 6-month-old infants during reaching, according to the hand used. More specifically, we examined if the use of the left or the right hand was linked to a specific type of visual exploration. Gaze direction during goal-directed reaching towards an object placed on the table was measured with a remote ASL 504 eye tracker (Bedford MA). Twelve babies aged 6 months were observed during six reaching sessions, alterning three sessions with an object on the left side of the subject and three with an object on the right side. Gaze direction and some hand variables (hand activity, hand opening and hand position from the body) were coded with The Observer software. Results showed that babies visually explore their reaching space differently according to the hand used: they look more at the object when they use their right hand and more around the object when they use their left hand; they also look more often at their left hand than at their right one. These results suggest that an asymmetric visuo-manual coordination exists as early as 6 months: vision seems to support (1) left hand during reaching for evaluate distances from object to baby by means of visual feedbacks and (2) right hand for identify what sort of object is. Results are discussed in light of manual specialization and specific hemispheric skills at this age.     

Category-specific visual agnosia: lesion to semantic memory versus extra-lesional variables in a case study and a connectionist model

There is a current debate on the causes of category-specific agnosia. The aim of this study was to examine the effects of lesional and extra-lesional variables on object recognition. Extra-lesional variables, such as visual complexity or familiarity, are factors that influence recognition. Using a connectionist model based on study, we provide evidence that extra-lesional variables can yield dissociations in the recognition rate of different categories. Furthermore, it is shown that lesional and extra-lesional variables can interact (p < .01) when both are simultaneously modeled. Category-specific agnosia might thus result from complex interactions.     

Infants learn phonotactic regularities from brief auditory experience

Two experiments investigated whether novel phonotactic regularities, not present in English, could be acquired by 16.5-month-old infants from brief auditory experience. Subjects listened to consonant-vowel-consonant syllables in which particular consonants were artificially restricted to either initial or final position (e.g. /baep/ not /paeb/). In a later head-turn preference test, infants listened longer to new syllables that violated the experimental phonotactic constraints than to new syllables that honored them. Thus, infants rapidly learned phonotactic regularities from brief auditory experience and extended them to unstudied syllables, documenting the sensitivity of the infant's language processing system to abstractions over linguistic experience.     

Human perception of verticality: Psychophysical experiments on the centrifuge and their neuronal implications

The role of the otoliths in the perception of verticality is analyzed in two different gravitational environments, 1 g and 1.5 g , and in different roll body positions between upright and upside down. The subjective visual vertical (SVV) is determined when a subject judges the orientation of an indicator as apparently vertical. An increase of g level hardly affects the SVV in the subject's frontal plane (y-z plane). However, for the first time, a three-dimensionally adjustable indicator was used for the SVV and this revealed a new phenomenon: An increase of g level induces a backward slant of the SVV into subject's median plane (x-z plane). The data are discussed with regard to Mittelstaedt's SVV theory; particular emphasis is given to the otolith-head coordinate transformation and the normalization of afferent otolith components. The results of this study provide evidence that the former is implemented at an earlier level and thus precedes the latter.     

What we know about what we have never heard: evidence from perceptual illusions

Are speakers equipped with preferences concerning grammatical structures that are absent in their language? We examine this question by investigating the sensitivity of English speakers to the sonority of onset clusters. Linguistic research suggests that certain onset clusters are universally preferred (e.g., bd>lb). We demonstrate that such preferences modulate the perception of unattested onsets by English speakers: Monosyllabic auditory nonwords with onsets that are universally dispreferred (e.g., lbif) are more likely to be classified as disyllabic and misperceived as identical to their disyllabic counterparts (e.g., lebif) compared to onsets that are relatively preferred across languages (e.g., bdif). Consequently, dispreferred onsets benefit from priming by their epenthetic counterpart (e.g., lebif-lbif) as much as they benefit from identity priming (e.g., lbif-lbif). A similar pattern of misperception (e.g., lbif-->lebif) was observed among speakers of Russian, where clusters of this type occur. But unlike English speakers, Russian speakers perceived these clusters accurately on most trials, suggesting that the perceptual illusions of English speakers are partly due to their linguistic experience, rather than phonetic confusion alone. Further evidence against a purely phonetic explanation for our results is offered by the capacity of English speakers to perceive such onsets accurately under conditions that encourage precise phonetic encoding. The perceptual illusions of English speakers are also irreducible to several statistical properties of the English lexicon. The systematic misperception of universally dispreferred onsets might reflect their ill-formedness in the grammars of all speakers, irrespective of linguistic experience. Such universal grammatical preferences implicate constraints on language learning.     

The human sense of the head's polarity is influenced by changes in the magnitude of gravity

The present investigation concerns the integrity of a primary mental function, the egocentric frame of reference and the sense of polarity of one's own head. The visually perceived eye level (VPEL) and the subjective antero-posterior axis of the head were measured by means of a visual indicator in darkness during two stimulus conditions: static pitch (sagittal-plane) tilting in the 1-g environment and gondola centrifugation (2G). It is demonstrated that an increase in the magnitude of the gravitoinertial (G) force, acting in the direction of the head and body long (z) axis, causes a substantial change not only in the VPEL but also in the perceived direction of the antero-posterior axis of the head.     

The pop out of scene-relative object movement against retinal motion due to self-movement

An object that moves is spotted almost effortlessly; it "pops out". When the observer is stationary, a moving object is uniquely identified by retinal motion. This is not so when the observer is also moving; as the eye travels through space all scene objects change position relative to the eye producing a complicated field of retinal motion. Without the unique identifier of retinal motion an object moving relative to the scene should be difficult to locate. Using a search task, we investigated this proposition. Computer-rendered objects were moved and transformed in a manner consistent with movement of the observer. Despite the complex pattern of retinal motion, objects moving relative to the scene were found to pop out. We suggest the brain uses its sensitivity to optic flow to "stabilise" the scene, allowing the scene-relative movement of an object to be identified.     

不良生活方式作用途径及其控制

不良生活方式影响健康的途径包括：病从口入;生活放纵造成机体的衰竭;享受型生活方式“废用”性的机体退化;生活中的失慎与失范导致直接的伤亡;生活压力导致的机体受损;挑战生理极限的心理、生理代价．改变不良生活方式应当遵从科学的原则和一定的标准。     

When the "I" looks at the "Me": autobiographical memory, visual perspective, and the self

This article presents a theoretical model of the self processes involved in autobiographical memories and proposes competing hypotheses for the role of visual perspective in autobiographical memory retrieval. Autobiographical memories can be retrieved from either the 1st person perspective, in which individuals see the event through their own eyes, or from the 3rd person perspective, in which individuals see themselves and the event from the perspective of an external observer. A growing body of research suggests that the visual perspective from which a memory is retrieved has important implications for a person’s thoughts, feelings, and goals, and is integrally related to a host of self-evaluative processes. We review the relevant research literature, present our theoretical model, and outline directions for future research.