Visual Information Processing Speed in Hypnotized and Nonhypnotized Subjects

Using a backward-masking paradigm with a bias-free and ceiling-free psychophysical task, we tested hypnotized and control subjects for speed of visual information processing. Approximately half of each group received visual imagery suggestions in an attempt to influence attention. Imagery produced no significant differential effect. Although an absence of a hypnotizability-performance relationship was in keeping with findings of a previous study, those subjects in the present study who performed under hypnosis were, as a group, significantly superior to the other subjects in speed of information processing.     

视觉加工速度、瞬间信息整合特征与汉语学习困难

采用因素实验设计,通过与正常学生与听力损伤学生对比实验研究,探讨汉语学习困难学生视觉加工速度和视觉瞬间信息整合的特征。结果表明:(1)汉语学习困难学生存在基本视觉加工速度不足以及汉语语言文字视觉加工的特异性困难;(2)汉语学习困难学生需要更长时间整合瞬间视觉信息,从而影响了其加工的速度;(3)适当延长视觉刺激整合的时间,可以有效提高其视觉加工的效率。这些结果对改善学生的汉语学习困难具有一定的指导意义。     

Induced self-motion in central vision

Previous research on visually induced self-motion found that stimulation of the central visual field (up to 30 degrees in diameter) results in perceived object motion while self-motion requires peripheral stimulation. In the present study, perceived self-motion was induced with a radially expanding pattern simulating observer motion through a space filled with dots, with visual angles of 7.5 degrees, 10.6 degrees, 15 degrees, and 21.2 degrees. Speed and texture density were also varied. The duration of reported self-motion (a) decreased with increased speed, (b) failed to increase with increased visual angle, and (c) decreased with visual angle at the highest speed level. In a second experiment, subjects rated the perceived depth of the displays. The speed and speed/area interaction effects on judged depth matched those found for induced self-motion. These results suggest an extension of the focal/ambient theory: In addition to a more primitive ambient processing mode that requires peripheral vision, there is a higher level system concerned with ambient processing that functions in the central visual field and uses more complex stimulus information, such as internal depth represented in a radially expanding pattern.     

Temporal integration between visual images and visual percepts

Using a temporal integration task, subjects in 5 experiments were expected to combine information from temporally separated visual presentations. Evidence from these experiments indicated that perceptual information can be integrated with previously generated and currently maintained visual images to form a representation that contains information from each source. Properties and limitations of this integration process were also explored, including the time required to generated the image, the speed at which percepts were integrated with images, and the capacity of the representation. Implications for theories of visual processing and memory are discussed.     

The role of attention in one-handed catching

The present study investigated the contribution of attention to one-handed catching success. A group of skilled (n = 8) and less skilled (n = 9) male subjects were compared in their ability to process secondary task information while executing a primary one-handed catching task. On 40% of the trials, a secondary visual stimulus (SVS) was presented in the peripheral visual field at predetermined times during the flight of the ball. On these trials, the subject was required to complete the one-handed catch and immediately throw the ball at a stationary target. Less skilled subjects made significantly more catching errors under both normal viewing and dual-task processing conditions. The differences were due to errors of positioning rather than grasping. Positioning of the hand appears to require visual attention regardless of skill level, as both skill groups experienced increased difficulty processing secondary task information as the ball approached the catching hand.     

The development of letter processing efficiency

The development of efficiency in letter processing skills was studied using a letter search task. In two experiments, subjects searched for a target letter displayed with items varying in their visual featural or conceptual categorical similarity to the target. Accuracy and reaction time of search were evaluated for evidence of the visual search “category effect.” In order to determine if subjects could efficiently use knowledge of stimulus differences to facilitate search, conditions tested search time as a function of the amount of information to be processed both within the visual display and in short-term memory. In the two experiments, subjects of ages 6 years through adulthood showed the category effect; however, efficiency of letter processing was found to be related to the amount of information that had to be processed in memory. While there were drastic changes in search speed with increasing grade level, patterns of processing were consistent, leading to the conclusion that the knowledge required to process the letter information accurately is acquired very early. Results were discussed in terms of the distinctions among accuracy, automaticity, and efficiency of skill development and the relationship of these to general reading and intellectual development.     

Visual information and skill level in time-to-collision estimation

Previous studies on the visual origin of time-to-collision (Tc) information have demonstrated that Tc estimates can be based solely on the processing of target expansion rate (optic variable tau). But in the simulated situations used (film clips), there was little reliable information on speed (owing to reduced peripheral vision) and distance (owing to the absence of binocular distance cues) available. In order to determine whether these kinds of information are also taken into account, it is necessary to take an approach where the subject receives a more complete visual input. Thus, an experiment conducted on a circuit under actual driving conditions is reported. Experienced drivers and beginners, who were passengers in a car, had to indicate the moment they expected a collision with a stationary obstacle to take place. Subjects were blindfolded after a viewing time of 3 s. The conditions for speed evaluation (normal versus restricted visual field) and distance evaluation (binocular versus monocular vision) by subjects were varied. The approach speed (30 and 90 km h-1) and actual Tc (3 and 6 s) were also varied. The results show that accuracy of Tc estimation increased with (i) normal visual field, (ii) binocular vision, (iii) higher speeds, and (iv) driving experience. These findings have been interpreted as indicating that both speed and distance information are taken into account in Tc estimation. They suggest furthermore that these two kinds of information may be used differently depending on the skill level of the subject. The results are discussed in terms of the complementarity of the various potentially usable visual means of obtaining Tc information.     

Prenatal cocaine exposure and infant cognition

The present study examined the relationship of prenatal cocaine exposure to infant information processing in the first year of life.In a prospective, longitudinal study of 177 cocaine-exposed and 175 non-exposed infants, the Fagan Test of Infant Intelligence (FTII) was used to measure attention, visual recognition memory and information processing speed at 6.5 and 12 months of age. Groups were compared over time using mixed linear model analyses.Prenatal cocaine exposure predicted poorer visual recognition memory at 12 months, with exposed infants obtaining lower mean scores and a higher percentage of scores in the risk range. Across exposure groups, information processing speed increased with age, demonstrating a developmental effect. Tobacco and marijuana exposures were related to faster looking times, which did not relate to visual recognition memory.Cognitive deficits and attentional problems noted in prior studies of cocaine-exposed children at later ages may be detectable in infancy.     

Influence of auditory-verbal, visual-verbal, visual, and visual-visual processing speed on reading and spelling at the end of Grade 1

This study examined cognitive processing speed through four modalities (auditory-verbal, visual-verbal, visual, and visual-visual) at the end of Grade 1 and how it influences reading and spelling. The subjects were 124 French-speaking children, selected for their contrasting performance on reading and spelling tasks. The children in the first group (N=69) were average readers; the second group of children (N=55) performed worse or much worse on all reading and spelling tasks. The experimental design consisted of a set of 10 tasks administered in two sessions. The major findings reveal that: (1) the children with reading difficulties displayed low and slow performance on most cognitive tasks, whatever the modality; (2) auditory-verbal and visual-verbal processing speed significantly predicted written language, which was not the case with the visual modalities; and (3) that visual problems did not appear to be a potential cause of reading problems in most delayed readers. The findings also confirm the independence of phonological and naming-speed skills in reading development and reading impairment.     

Perceptual organization and schizotypy.

The preattentive visual information processing of hypothetically psychosis-prone college subjects was evaluated using three different paradigms, target detection (n = 57), visual suffix effect (n = 57), and configural superiority effect (n = 68). It was hypothesized that anhedonic subjects would show the same perceptual organization deficits reported in process schizophrenics and that perceptual aberration-magical ideation subjects and depressed subjects would perform similarly to control subjects. In each study, anhedonics performed similarly to each comparison group, even though there was adequate power to detect performance differences if they existed. A framework for understanding the visual information-processing deficits of schizophrenics and high-risk subjects is proposed.     

Residual effects of zolpidem,zopiclone and flunitrazepam on the processing of visual information in driving context

Drivers who had taken hypnotic medications such as benzodiazepines are over-represented in road accidents. Experimental studies show that, even the day after, these drugs induce an impairment of real or simulated driving. To remedy the undesirable side-effects of hypnotics, new families of such drugs have been developed, their residual effects on visual information processing functions are poorly documented. We therefore compared the residual effects of two hypnotics, zopiclone (7.5 mg) and zolpidem (10 mg), and those of an old one, flunitrazepam (1 mg), versus a placebo on the capacities of subjects to estimate their own speed of movement and to anticipate a situation of collision with another vehicle parked along their trajectory. We found no modification in the processing of visual information the day after taking an active molecule. As these perceptive tasks have been demonstrated to be sensitive to environmental and individual factors, we can conclude that own speed perception and time to collision estimation are not affected by the residual effects of the hypnotic drugs studied. Thus, the behavioural impairments observed in previous studies result from the alteration of other functions solicited when driving a vehicle.     

Left hemispheric preference and alexithymia: A neuropsychological investigation

Starting from the hypothesis that alexithymics show a hyperactive left hemisphere, this study investigated the neural processing of visual information in two alexi-thymic groups and one nonalexithymic group. The subjects performed a lateralised visual-matching task, through which the proportions of ipsilateral and contralateral processing of three types of stimuli were assessed. In line with the hypothesis it was demonstrated that, in contradistinction to nonalexithymics, the two groups of alexithymics showed a left hemispheric preference in their neural processing of emotion words.     

Direct perception of action-scaled affordances: the shrinking gap problem

The aim of this study was to investigate the perception of possibilities for action (i.e., affordances) that depend on one's movement capabilities, and more specifically, the passability of a shrinking gap between converging obstacles. We introduce a new optical invariant that specifies in intrinsic units the minimum locomotor speed needed to safely pass through a shrinking gap. Detecting this information during self-motion requires recovering the component of the obstacles' local optical expansion attributable to obstacle motion, independent of self-motion. In principle, recovering the obstacle motion component could involve either visual or non-visual self-motion information. We investigated the visual and non-visual contributions in two experiments in which subjects walked through a virtual environment and made judgments about whether it was possible to pass through a shrinking gap. On a small percentage of trials, visual and non-visual self-motion information were independently manipulated by varying the speed with which subjects moved through the virtual environment. Comparisons of judgments on such catch trials with judgments on normal trials revealed both visual and non-visual contributions to the detection of information about minimum walking speed.     

Visual and verbal modes of information processing and their relation to the effectiveness of cognitively-based anxiety-reduction techniques

This study examined the interaction between preferred modes of information processing (visual and verbal) and two cognitively-based anxiety-reduction techniques. One technique was based on the use of images as a coping strategy while the other employed a self-instructional approach. Thirty-six subjects reporting high levels of dental fear were assigned to one of three groups (two types of treatment and a no-treatment control). One-half of the subjects in each group had been identified as preferring the visual mode of information processing while for the other half the verbal mode was preferred. After treatment, subjects viewed an anxiety-inducing videotape depicting a visit to the dentist. Results indicated that, while both treatments were significantly effective in reducing self-reports of discomfort while viewing the videotape, there was no significant interaction between the type of treatment and preferred cognitive mode. The results were interpreted as indicating that treatment may override individual cognitive styles. Furthermore, the data suggested that the normal individual has the ability to adapt to divergent and non-preferred forms of information processing.     

Fatigue, cognitive functioning and psychological distress in Marfan syndrome, a pilot study

Marfan patients report fatigue as a major subjective complaint. We found no studies exploring the subject. The aim of this study was in a strictly defined Marfan population to assess self-reported fatigue, cognitive functions and psychological distress, correlations among them and correlations to visual acuity, joint hypermobility and use of beta-blockers. Sixteen subjects aged 18 - 30 years, fulfilling the Gent criteria, were assessed with the Fatigue Severity Scale, Fatigue Questionnaire, a comprehensive battery of neuropsychological tests and the General Health Questionnaire (GHQ). Self-reported fatigue was comparable with fatigue reported in other severe chronic diseases and disabilities, and was primarily in the mental/psychological domain. Psychological distress was higher than expected compared with the population at large. All neuropsychological test results were within the normal range, except for tests of visuo-motor coordination and speed of information processing. There was a significant inverse correlation between Fatigue Questionnaire ratings and some neuropsychological tests. Fatigue seems to be a serious problem for persons with Marfan syndrome and seems related to some areas of cognitive functioning. We found no overall impairment in cognitive functioning, but slightly reduced speed of information processing. Reduced visuo-motor coordination could be explained by impaired visual acuity.     

工作记忆负荷、形状干扰对聋人与听力正常人注意捕获影响的眼动研究

通过记录和分析被试的行为和眼动指标,本研究试图探讨不同工作记忆负荷下,形状干扰对聋人与听力正常人不同视野位置上刺激信息捕获注意的异同。研究结果表明：（1）形状干扰刺激虽然没有影响被试视觉加工的认知绩效,但被试的眼动模式会由于工作记忆负荷的改变而改变,高工作记忆负荷时,有形状干扰的注视次数高于无形状干扰。（2）工作记忆负荷、视野位置影响被试视觉加工任务的完成,被试在不同视野位置的加工过程表现出不一致的眼动模式。（3）聋人视觉加工在高工作记忆负荷时存在一定的劣势,但其对不同视野位置的信息加工及形状干扰所产生的注意捕获效应与听力正常人一致。     

Gait symmetric adaptation: Comparing effects of implicit visual distortion versus split-belt treadmill on aftereffects of adapted step length symmetry

Understanding gait adaptation is essential for rehabilitation, and visual feedback can be used during gait rehabilitation to develop effective gait training. We have previously shown that subjects can adapt spatial aspects of walking to an implicitly imposed distortion of visual feedback of step length. To further investigate the storage benefit of an implicit process engaged in visual feedback distortion, we compared the robustness of aftereffects acquired by visual feedback distortion, versus split-belt treadmill walking. For the visual distortion trial, we implicitly distorted the visual representation of subjects’ gait symmetry, whereas for the split-belt trial, the speed ratio of the two belts was gradually adjusted without visual feedback. After adaptation, the visual feedback or the split-belt perturbation was removed while subjects continued walking, and aftereffects of preserved asymmetric pattern were assessed. We found that subjects trained with visual distortion trial retained aftereffects longest. In response to the larger speed ratio of split-belt walking, the subjects showed an increase in the size of aftereffects compared to the smaller speed ratio, but it steeply decreased over time in all the speed ratios tested. In contrast, the visual distortion group showed much slower decreasing rate of aftereffects, which was evidence of longer storage of an adapted gait pattern. Visual distortion adaptation may involve the interaction and integration of the change in motor strategy and implicit process in sensorimotor adaptation. Although it should be clarified more clearly through further studies, the findings of this study suggest that gait control employs distinct adaptive processes during the visual distortion and split-belt walking and also the level of reliance of an implicit process may be greater in the visual distortion adaptation than the split-belt walking adaptation.     

视-听跨通道汉语词汇信息加工中的抑制机制

采用选择性再认的方法考察在汉语词汇加工过程中 ,视 -听跨通道信息与视觉单通道信息加工过程中的抑制机制。结果表明 :对于视觉词汇的总体再认“否”反应 ,单通道干扰条件下的成绩优于跨通道干扰条件下的成绩。在视觉词汇加工过程中 ,对外在干扰材料的抑制效率不受输入干扰刺激的通道的影响。抑制效率受干扰材料语义关系性的影响 ,与目标材料属于同一语义范畴的比异范畴的干扰材料更难以被抑制。     

Visual neglect and left-sided context effects

Patients with visual neglect generally fail to respond to an item placed on the left of a target location, even when both stimuli are situated in the right visual field. Little is known, however, about the level of processing for the unattended items. Two patients with left visual neglect served as subjects in several experiments measuring passive contextual effects of a left-sided item on responses to a focal target. The results reveal that a neglected item may influence the speed of responding. The findings are interpreted relative to the loci of context effects in normal subjects.     

Auditory coding of visual patterns for the blind

Recognition tasks of simple visual patterns have been used to assess an early visual--auditory sensory-substitution system, consisting of the coupling of a rough model of the human retina with an inverse model of the cochlea, by means of a pixel-frequency relationship. The potential advantage of the device, compared with previous ones, is to give the blind the ability to both localise and recognise visual patterns. Four evaluation sessions assessed the performance of twenty-four blindfolded sighted subjects using the device. Subjects had to recognise twenty-five visual patterns, one at a time, using a head-mounted small camera and interpreting the corresponding sounds given by the device. Half the subjects were trained by means of a correction feedback procedure during ten one-hour training sessions embedded in between the evaluation sessions. Results revealed extremely successful training effects. Performance of trained subjects significantly increased with practice compared with the untrained control group. The improvement was also observed for new patterns, demonstrating a learning-process generalisation. The negative correlation observed between scores and processing time showed that the subjects' response accuracy was related to their speed. In conclusion, simple pattern recognition is possible with a fairly natural vision-to-audition coding scheme, given the possibility for the subjects to have sensory--motor interactions while using the device.