Role Of Visual Information Research Articles

The role of visual information in the processing of place and manner features in speech perception.

Visual information provided by a talker's mouth movements can influence the perception of certain speech features. Thus, the "McGurk effect" shows that when the syllable (bi) is presented audibly, in synchrony with the syllable (gi), as it is presented visually, a person perceives the talker as saying (di). Moreover, studies have shown that interactions occur between place and voicing features in phonetic perception, when information is presented audibly. In our first experiment, we asked whether feature interactions occur when place information is specificed by a combination of auditory and visual information. Members of an auditory continuum ranging from (ibi) to (ipi) were paired with a video display of a talker saying (igi). The auditory tokens were heard as ranging from (ibi) to (ipi), but the auditory-visual tokens were perceived as ranging from (idi) to (iti). The results demonstrated that the voicing boundary for the auditory-visual tokens was located at a significantly longer VOT value than the voicing boundary for the auditory continuum presented without the visual information. These results demonstrate that place-voice interactions are not limited to situations in which place information is specified audibly.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of visual information in ball catching.

The present study is concerned with the perceptual information about the body and space underlying the act of catching a ball. In a series of four experiments, subjects were asked to catch a luminous ball under various visual conditions. In general, catching in a normally illuminated room was contrasted with catching the luminous ball in an otherwise completely dark room. In the third and fourth experiments, intermediate conditions of visual information were included. The results suggest that it is possible to catch a ball with one hand when only the ball is visible, but performance is better when the subject has the benefit of a rich visual environment and two hands. The second experiment indicated that subject performance does improve with practice in the dark, but time spent in the darkened room itself doesn't result in a significant decrement in performance. Results of the third study suggest that vision of one's hand does not aid in the performance of this task whereas the presence of a minimal visual frame appears to aid performance. The final study examined the relation between catching performance and body sway under similar visual conditions. Results of this experiment imply that persons who exhibit relatively little postural sway in full-room lighting performed better at this catching task.

The role of visual information in control of a constrained locomotor task.

The nature of visually guided locomotion was examined in an experiment where subjects had to walk to targets under various conditions. Target distance was manipulated so that subjects had to (a) lengthen their paces in order to hit the target; (b) shorten their paces; (c) make no adjustments to their standard pace length at all. They did this under four visual conditions: (a) normal vision; (b) with vision restricted to a "snapshot" each time the foot that was to be placed on the target was on the ground; (c) with a snapshot each time the foot to be placed was in the swing phase; and (d) no vision after departure fro the target. The results show that the subjects succeed in reaching the target in most cases. However, the smoothness and fluidity of their movements vary significantly between conditions. Under normal vision or where visual snapshots are delivered when the pointing foot is on the ground, locomotion is smoothly regulated as the subjects approach the target. where snapshots are delivered when the pointing foot is in the swing phase, regulation becomes clumsy and ill coordinated. Where no vision is available at all during the approach, adjustments are made, but these are least coordinated of all. The results show that well-coordinated visual regulation does not require continuous visual guidance but depends on intermittent information being available at the appropriate times in the action sequence. Such timing is often more important than the total amount of information that is available for guidance.

Infants' detection of visual-tactual discrepancies: asymmetries that indicate a directive role of visual information.

Infants' cross-modal functioning was investigated in two studies. In Study 1, 11-month-old infants were confronted with five different visual-tactual discrepancies created with a mirror arrangement. The infants' behavioral reactions to the discrepancies were compared with their behavior on matched control trials with a forced-choice judgement procedure. Infants detected discrepancies in which they saw an egg and felt a cube, saw a fur-covered cube and felt an egg, and saw a cross and felt a fur-covered cube. However, they provided no evidence that they detected discrepancies in which they saw a cube and felt a cross or saw a cube and felt a fur-covered cube. In Study 2, infants were confronted with discrepancies that were the converse of those which seemed to go unnoticed in Study 1: They saw either a cross or a fur-covered cube and felt a plain cube. Both of these new discrepancies were detected according to the forced-choice judgment procedure. The results indicate that texture as well as shape can serve as a basis for cross-modal matching for infants. The asymmetries in cross-modal matching that were observed across Studies 1 and 2 are interpreted as evidence that visual information plays a directive, goal-setting role for infants' manual explorations.

The role of visual information from a talker's face in the processing of place and manner features in speech

A number of studies have indicated that a dependency relation exists for the processing of place and manner features of articulation. Other studies have demonstrated that visual information provided by a talker's face can influence the perceived place of articulation of well-specified auditory tokens presented in synchrony with the visual information. Thus, when /bi/ is presented auditorially and /gi/ visually, a person perceives the talker as saying /di/. These findings raise the possibility that visual place information might also influence the processing of VOT. Members of an auditory continuum ranging from /ibi/ to /ipi/ were paired with a video display of a talker saying /igi/. The auditory tokens were heard as ranging from /ibi/ to /ipi/, while the audio/visual tokens were perceived as ranging from /idi/ to /iti/. We found that the VOT boundary for the audio/visual tokens was located at a significantly longer value than the VOT boundary for the auditory continuum presented without the visual information. These results indicate that, under certain circumstances, the processing of VOT information takes into account both auditory and visual place information. [Research supported by NIH.]

The accuracy of aimed movements to visual targets during development: The role of visual information

Children aged 1.5 to 8 years were required to touch accurately an illuminated target lamp located on a vertical board. Movements were made when visual information was (1) complete (target lit for 3 s, room illuminated; (2) partial (target lit for 3 s, room dark, and (3) reduced (target lit for 0.7 s, room dark). Dependent variables were response accuracy, reaction time; and movement time. Accuracy decreased with decreasing availability of visual information and improved with age under all conditions. Reaction times were shorter in the dark (Conditions 2 and 3) than in the light; they decreased with age up to age 5 and did not continue to decrease thereafter. Movement time did not change with age under Conditions 1 and 3 but tended to increase with age under Condition 2. Slower movements were more accurate at all ages, provided visual feedback could be utilized. Increased reliance on the strategy “slower movements yield higher accuracy” was held to account for developmental changes under Condition 2, whereas in Conditions 1 and 3 improvement in the efficiency of motor preprogramming was implicated.