Representational momentum and children's sensori-motor representations of objects

Recent research has shown that 2-year-olds fail at a task that ostensibly only requires the ability to understand that solid objects cannot pass through other solid objects. Two experiments were conducted in which 2- and 3-year-olds judged the stopping point of an object as it moved at varying speeds along a path and behind an occluder, stopping at a barrier visible above the occluder. Three-year-olds were able to take into account the barrier when searching for the object, while 2-year-olds were not. However, both groups judged faster moving objects to travel farther as indicated by their incorrect reaches. Thus, the results show that young children's sensori-motor representations exhibit a form of representational momentum. This unifies the perceptually based representations of early childhood with adults' dynamic representations that incorporate physical regularities but that are also available to conscious reasoning.     

Advance visual information, awareness, and anticipation skill

The authors examined 13 skilled, 13 recreational, and 11 novice players' awareness of the advance visual information that they used to judge tennis serve direction. Participants viewed video clips of serve actions under 5 conditions of spatial occlusion. The authors assessed participants' awareness by comparing the different groups' confidence associated with correct and incorrect judgments and by conducting a postexperiment free-recall test. The results indicated that information from the ball toss and the arm + racquet region underpinned players' anticipation skill and that greater expertise was accompained by increasing awareness of the information on which judgments were based. The authors discuss the implications of the present results for researchers' use of confidence ratings to assess awareness in perceptual-judgment tasks.     

Sex differences in verbal skills: Use of spelling-sound and lexical information

An experiment is described in which possible sex differences in lexical and phonological skills were investigated. A spelling test was used which could not be done on a phonological basis alone and which entailed lexical access for good performance. Women were judged on the evidence for this task to have better lexical ability than men, but no difference was found on a task designed to tap knowledge and use of phonological information in the form of spelling-sound correspondences.     

The development of visual information processing skills related to reading

Literate adults can use their familiarity with specific words and their knowledge of English orthography to facilitate word recognition processes. The development of word superiority effects in visual perception was investigated in the present study using a search task with kindergarten (5.7 years old), second (8.0 years old), and fourth grade children (10.0 years old), and college students. The search task consisted of the visual presentation of a target letter followed by a three-, four-, or five-letter display. The target letter was included in the display on half the trials, and the displays were common words, orthographically regular pseudowords, and irregular nonwords. Although response times decreased with age, the three oldest groups showed similar effects for the size and structure of the displays. That is, response times increased linearly with the number of display letters, and responses were faster for word and pseudoword displays than for nonwords. The data for the kindergarten children showed evidence for the use of a different search strategy, and they did not respond differentially to the three types of displays. The results are discussed in terms of the implications for developmental models of visual search and word superiority effects in visual perception.     

Only self-generated actions create sensori-motor systems in the developing brain

Previous research shows that sensory and motor systems interact during perception, but how these connections among systems are created during development is unknown. The current work exposes young children to novel 'verbs' and objects through either (a) actively exploring the objects or (b) by seeing an experimenter interact with the objects. Results demonstrate that the motor system is recruited during auditory perception only after learning involved self-generated interactions with objects. Action observation itself led to above-baseline activation in one motor region during visual perception, but was still significantly less active than after self-generated action. Therefore, in the developing brain, associations are built upon real-world interactions of body and environment, leading to sensori-motor representations of both objects and words.     

The part played by intellectual processes in a sensori-motor performance

An experimental method is described for investigating the relation between intellectual processes and hand movements as both develop during the learning of a skilled task. Subjects were required to make predictive movements to join a series of circles; these appeared one at a time and were arranged in a pattern which was repeated thirty-two times. Comparison between the record of predictive movements and the subject's drawing of the pattern, made at the end of the experiment, showed that errors in the drawing corresponded to the type of response first made when the whole pattern was unfamiliar. For this reason it is suggested that the making of the responses played a part in the development of the idea of the pattern of circles, but the relation between the two is not a simple one.     

Sensory and sensori-motor adaptations in strabismus: Their role in space perception

In comitant strabismus many perceptual adaptive processes take place, which involve perception of space. Suppression of the image of the deviated eye and anomalous retinal correspondence (ARC) are the two main antidiplopic mechanisms. ARC may be present without suppression in small-angle strabismus (up to 10 degrees), supporting an anomalous binocular cooperation in spite of the deviation. Both psychophysical and electrophysiological evidence for anomalous binocular vision in strabismus are provided. Sensori-motor adaptations in strabismus develop as well. They are represented by vergence eye movements which, although not identical to, have similar characteristics as normal fusional vergences. These anomalous fusional eye movements tend to return the eyes to their original deviation when elements are introduced to change the position of the eyes, e.g., prisms or surgery. In conjunction with ARC, these movements serve to maintain binocular visual perception despite the strabismus.     

On the relationship between coding and the ability to see what one is doing in a sensori-motor task

In order to examine the possible interaction between different display-control relationships and the ability to look at what one is doing an experiment was carried out under four conditions: half the subjects were trained with a colour code display, the other half with a positional code; within each of these groups half the subjects were allowed to look at their hand while performing, and the others were not. It was found that the effect of not being allowed to look was larger with the colour code in the initial phase of training, and larger with the positional code in the final phase of training.     

Catching skills in infancy

Infants were induced to reach for fast moving objects whose velocity and starting position varied. Altogether, 144 reaches were analyzed by a technique that took into consideration the three-dimensional properties of reaches. It was found that reaches in all conditions were aimed close to the meeting point with the object. The precision in timing of a reach was about a twentieth of a second, and the systematic timing errors were close to zero. The results suggest that the infant reaches in reference to a coordinate system fixed to the moving object instead of to the static background, that is, the infant's hand is moved with the object at the same time as it is moved toward the object. It is concluded that the capacity to time and coordinate one's movements in the catching of a moving object is a very basic and early developed skill.     

So-called slow posterior activity in the EEG and the sensori-motor reaction time. Results of re-examinations made after 5 years

Six persons showing what is called slow posterior activity (4/s rhythm) in the electroencephalogram were reexamined after a period of five years. Sensorimotor reaction times were recorded in addition to the electroencephalogram which was analyzed for the frequency of LPA and for the degree of stability of time dependence. The frequency and distinctness of LPA were found to be stable after five years (r = 0.09 and 0.82, respectively; p less than 0.001), whereas the alpha rhythmus of the subjects had undergone considerable changes (r = 0.34; p greater than 0.05). The extension of reaction times to be observed under the influence of LPA was also seen to remain constant (r = 0.79; p less than 0.05). Accordingly, LPA proved an extremely stable characteristic which did not show any substantial variations in the course of five years.     

The relationship of neuronal activity within the sensori-motor region of the subthalamic nucleus to speech

Microelectrode recordings of human sensori-motor subthalamic neuronal activity during spoken sentence and syllable-repetition tasks provided an opportunity to evaluate the relationship between changes in neuronal activities and specific aspects of these vocal behaviors. Observed patterns of neuronal activity included a build up of activity in anticipation of the start of the utterance, a marked reduction in activity associated with the start of the utterance, and a burst of activity during the course of the sentence between the noun phrase and the verb phrase. Overall, changes of neuronal activity were more robust for the sentence repetition task. These data suggest that the basal ganglia play a role in generating meaningful speech utterances, which may parallel its role in complex sequential limb movements. It is possible that the basal ganglia play a role in generating the syntactical structure of language.     

Contextual dependencies in motor skills

The development of contextual dependencies during motor skill acquisition was examined. Environmental context was varied along intentional and incidental dimensions. Intentional stimuli were defined as essential for achieving skilled performance, whereas incidental stimuli were defined as those that have the potential to become associated with specific tasks due to their selective presence in the learning environment. Experiment 1 demonstrated the occurrence of contextual dependencies for the learning of four-key typing sequences. Contextual dependencies were diminished in Experiment 2 when the number of keys used in the sequences was reduced. In Experiment 3, a retention condition was incorporated, in which both the intentional and the incidental stimuli were not available; this confirmed that task difficulty mediated the development of contextual dependencies. These findings are discussed with respect to the incorporation of environmental contextual stimuli with memorial representations of movement information.     

Developmental changes in attention-deployment skills

The ability to efficiently allocate attention between two tasks differing in payoff was investigated developmentally. Ten subjects from each of three grade levels (second, fourth, and college) performed an auditory and a visual memory task simultaneously. Modality of the primary task, difficulty of the primary task, and difficulty of the secondary task were varied factorially within subjects. The difference between primary and secondary performances increased with age: All college students, about half of the fourth graders, and none of the second graders showed a meaningful degree of differentiation between primary and secondary tasks.     

Visual skills in airport-security screening

Abstract— An experiment examined visual performance in a simulated luggage-screening task. Observers participated in five sessions of a task requiring them to search for knives hidden in x-ray images of cluttered bags. Sensitivity and response times improved reliably as a result of practice. Eye movement data revealed that sensitivity increases were produced entirely by changes in observers' ability to recognize target objects, and not by changes in the effectiveness of visual scanning. Moreover, recognition skills were in part stimulus-specific, such that performance was degraded by the introduction of unfamiliar target objects. Implications for screener training are discussed.     

Auditory temporal information processing in preschool children at family risk for dyslexia: relations with phonological abilities and developing literacy skills

In this project, the hypothesis of an auditory temporal processing deficit in dyslexia was tested by examining auditory processing in relation to phonological skills in two contrasting groups of five-year-old preschool children, a familial high risk and a familial low risk group. Participants were individually matched for gender, age, non-verbal IQ, school environment, and parental educational level. Psychophysical thresholds were estimated for gap-detection, frequency modulation detection, and tone-in-noise detection using a three-interval forced-choice adaptive staircase paradigm embedded within a computer game. Phonological skills were measured by tasks assessing phonological awareness, rapid serial naming, and verbal short-term memory. Significant group differences were found for phonological awareness and letter knowledge. In contrast, none of the auditory tasks differentiated significantly between both groups. However, both frequency modulation and tone-in-noise detection were significantly related to phonological awareness. This relation with phonological skills was not present for gap-detection.     

Relationships among spatial skills, communication skills, and field independence in deaf students

The hypotheses that deaf students would be more field-dependent than hearing students and that their competence in communication skills would be positively related to field-independence were supported for a group of 77 male and 67 female deaf students. Step-wise multiple regression analyses of the data showed that for females spatial skills followed by communication skills were significant predictors of field-independence; for males spatial skills followed by the extent of hearing loss were significant predictors of field-independence. Sex differences found on tests of field-independence and spatial relations were consistent with those obtained from the hearing population. It was suggested that socialization experiences and competence in communication skills may influence development of field-independence in deaf students.