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Obstacle detection is an important visual task for pedestrians. An experiment was carried out to measure the ability to detect peripheral obstacles under variations of illuminance and scotopic/photopic luminance ratio and with older and younger test participants. The LED array used in this work enabled scotopic/photopic ratio to be varied whilst chromaticity was held constant. The tests employed a full-scale model with dynamic fixation and walking to better simulate pedestrian experience than in past work. Detection performance increased with illuminance, reaching a plateau at 2.0 lux. A higher scotopic/photopic ratio improved obstacle detection but only at the lowest illuminance used in this study (0.2 lux). Older participants showed poorer obstacle detection performance than younger participants but again only at the lowest illuminance.

The perirhinal cortex (PRH) is considered a crucial cortical area for familiarity memory and electrophysiological studies have reported the presence of visual familiarity encoding neurons in PRH. However, recent evidence has questioned the existence of these neurons. Here, we used a visual task in which head-restrained mice were passively exposed to oriented gratings or natural images. Evoked potentials and single-unit recordings showed evoked responses to novelty in V1 under some conditions. However, the PRH showed no response modulation with respect to familiarity under a variety of different conditions or retention delays. These results indicate that the PRH does not contribute to familiarity/novelty encoding using passively exposed visual stimuli.

The metabolic activity pattern of the monkey visual cortex was mapped quantitatively with [14C]-2-deoxyglucose during the performance of a visually guided reaching task. After bandpass filtering of the reconstructed two-dimensional metabolic maps of areas V1 and V2, alternating bands of high and low metabolic activity were apparent in control and experimental hemispheres. The spatial arrangement of active bands was studied with two-dimensional spectral analysis, and bands were found to be more organized in the experimental monkey. In area V1 of the control monkey the spectral amplitude was spread over a wider range of directions and frequencies than in the experimental subject. The finding that layer IV is characterized by more complex spectra than layers I through III suggests the coexistence of more than one active columnar system in the geniculorecipient layer. In area V2, stripes running almost perpendicular to the V1/V2 border were found along with superimposed patches of enhanced metabolic activity. In the experimental hemispheres, the corresponding spectra were extremely sharp yielding a constant periodicity. It is suggested that the well-organized columnar arrangement within areas V1 and V2 of the experimental hemispheres emerges from the diffusely organized background network of activity patterns in the control state.

By the year 2024, 25% of drivers in the U.S. will be over the age of 65. Older drivers have more crashes and fatalities per mile driven than any other adult age group. Although driving is a highly visual task and vision impairment is more prevalent in the elderly, previous research has failed to identify visual factors which are strongly associated with increased crashes in the elderly. Using a comprehensive approach to assess several aspects of visual processing in a large sample of older drivers, this study has identified a measure of visual attention that had high sensitivity (89%) and specificity (85%) in predicting which older drivers had a history of crash problems, a level of predictability unprecedented in research on crash risk in older drivers. The “useful field of view”, as it is called, measures the spatial area within which an individual can be rapidly alerted to visual stimuli. Older adults with substantial shrinkage in the useful field of view were six times more likely to have incurred one or more crashes in the previous five year period. By comparison, visual sensory function, cognitive status, and chronological age were poor predictors of crash involvement. This study suggests that policies which restrict driving privileges based solely on age or on stereotypes of age-related declines in vision and cognition are scientifically unfounded. With the identification of a visual attention measure highly predictive of crash problems in the elderly, decisions on the suitability of licensure in the older adult population can be based on objective, visual-performance-based criteria.

A B S T R A C TIntroduction: Craving to methamphetamine is a significant health concern and exposure to methamphetamine cues in laboratory can induce craving. In this study, a task designing procedure for evaluating methamphetamine cue-induced craving in laboratory conditions is examined. Methods: First a series of visual cues which could induce craving was identified by 5 discussion sessions between expert clinicians and 10 methamphetamine smokers. Cues were categorized in 4 main clusters and photos were taken for each cue in studio, then 60 most evocative photos were selected and 10 neutral photos were added. In this phase, 50 subjects with methamphetamine dependence, had exposure to cues and rated craving intensity induced by the 72 cues (60 active evocative photos + 10 neutral photos) on self report Visual Analogue Scale (ranging from 0-100). In this way, 50 photos with high levels of evocative potency (CICT 50) and 10 photos with the most evocative potency (CICT 10) were obtained and subsequently, the task was designed. Results: The task reliability (internal consistency) was measured by Cronbach’s alpha which was 91% for (CICT 50) and 71% for (CICT 10). The most craving induced was reported for category Drug use procedure (66.27±30.32) and least report for category Cues associated with drug use (31.38±32.96). Difference in cue-induced craving in (CICT 50) and (CICT 10) were not associated with age, education, income, marital status, employment and sexual activity in the past 30 days prior to study entry. Family living condition was marginally correlated with higher scores in (CICT 50). Age of onset for (opioids, cocaine and methamphetamine) was negatively correlated with (CICT 50) and (CICT 10) and age of first opiate use was negatively correlated with (CICT 50). Discussion: Cue-induced craving for methamphetamine may be reliably measured by tasks designed in laboratory and designed assessment tasks can be used in cue reactivity paradigm, and imaging studies related to methamphetamine dependence.

The European traffic sign system encodes the meaning of a sign by use of varying forms, colours and symbols. However, signs differ greatly in how explicit their message is. Thus, the meaning of most direction signs is self-evident, while that of some others is less obvious. The European built-up area sign limits driving speed to 50 km/h, like speed limit signs, but its rectangular form and symbol not associated with speed limit distinguish it clearly from standard speed limit signs. Also, the function of the built-up area sign is more complex than the one of speed limit signs: the built-up area sign both limits speed and informs about entering a built-up area. The purpose of this study was to investigate whether the built-up area sign is noticed and obeyed as well as speed limit signs. In three field experiments the 50 km/h, 80 km/h signs and built-up area signs were alternated and speed changes were measured. Results indicated that the built-up area signs elicit only negligible speed responses compared t...

The relationship between electrophysiological and functional magnetic resonance imaging (fMRI) signals remains poorly understood. To date, studies have required invasive methods and have been limited to single functional regions and thus cannot account for possible variations across brain regions. Here we present a method that uses fMRI data and singe-trial electroencephalography (EEG) analyses to assess the spatial and spectral dependencies between the blood-oxygenation-level-dependent (BOLD) responses and the noninvasively estimated local field potentials (eLFPs) over a wide range of frequencies (0–256 Hz) throughout the entire brain volume. This method was applied in a study where human subjects completed separate fMRI and EEG sessions while performing a passive visual task. Intracranial LFPs were estimated from the scalp-recorded data using the ELECTRA source model. We compared statistical images from BOLD signals with statistical images of each frequency of the eLFPs. In agreement with previous studies in animals, we found a significant correspondence between LFP and BOLD statistical images in the gamma band (44–78 Hz) within primary visual cortices. In addition, significant correspondence was observed at low frequencies (100 Hz). Effects within extrastriate visual areas showed a different correspondence that not only included those frequency ranges observed in primary cortices but also additional frequencies. Results therefore suggest that the relationship between electrophysiological and hemodynamic signals thus might vary both as a function of frequency and anatomical region.

Auditory change detection has been studied extensively with mismatch negativity (MMN), an event-related potential. Because it is unresolved if the duration MMN depends on sound pressure level (SPL), we studied effects of different SPLs (56, 66, and 76dB) on the duration MMN. Further, previous research suggests that the MMN is reduced by a concurrent visual task. Because a recent behavioral study found that high visual perceptual load strongly reduced detection sensitivity to irrelevant sounds, we studied if the duration MMN is reduced by load, and if this reduction is stronger at low SPLs. Although a duration MMN was observed for all SPLs, the MMN was apparently not moderated strongly by SPL, perceptual load, or their interaction, because all 95% CIs overlapped zero. In a contrast analysis of the MMN (across loads) between the 56-dB and 76-dB groups, evidence (BF=0.31) favored the null hypothesis that duration MMN is unaffected by a 20-dB increase in SPL. Similarly, evidence (BF=0.19) favored the null hypothesis that effects of perceptual load on the duration MMN do not change with a 20-dB increase in SPL. However, evidence (BF=3.12) favored the alternative hypothesis that the effect of perceptual load in the present study resembled the overall effect in a recent meta-analysis. When the present findings were combined with the meta-analysis, the effect of load (low minus high) was -0.43μV, 95% CI [-0.64, -0.22] suggesting that the duration MMN decreases with load. These findings provide support for a sensitive monitoring system of the auditory environment.

It is now well known that the absence of attention can leave people unaware of both visual and auditory stimuli (e.g., Dalton & Fraenkel, 2012; Mack & Rock, 1998). However, the possibility of similar effects within the tactile domain has received much less research. Here, we introduce a new tactile inattention paradigm and use it to test whether tactile awareness depends on the level of perceptual load in a concurrent visual task. Participants performed a visual search task of either low or high perceptual load, as well as responding to the presence or absence of a brief vibration delivered simultaneously to either the left or the right hand (50% of trials). Detection sensitivity to the clearly noticeable tactile stimulus was reduced under high (vs. low) visual perceptual load. These findings provide the first robust demonstration of "inattentional numbness," as well as demonstrating that this phenomenon can be induced by concurrent visual perceptual load. (PsycINFO Database Record

To be correctly mastered, brain-computer interfaces (BCIs) need an uninterrupted flow of feedback to the user. This feedback is usually delivered through the visual channel. Our aim was to explore the benefits of vibrotactile feedback during users' training and control of EEG-based BCI applications. A protocol for delivering vibrotactile feedback, including specific hardware and software arrangements, was specified. In three studies with 33 subjects (including 3 with spinal cord injury), we compared vibrotactile and visual feedback, addressing: (I) the feasibility of subjects' training to master their EEG rhythms using tactile feedback; (II) the compatibility of this form of feedback in presence of a visual distracter; (III) the performance in presence of a complex visual task on the same (visual) or different (tactile) sensory channel. The stimulation protocol we developed supports a general usage of the tactors; preliminary experimentations. All studies indicated that the vibrotactile channel can function as a valuable feedback modality with reliability comparable to the classical visual feedback. Advantages of using a vibrotactile feedback emerged when the visual channel was highly loaded by a complex task. In all experiments, vibrotactile feedback felt, after some training, more natural for both controls and SCI users.

Subjects simultaneously performed visual and auditory detection tasks. Pupillary dilation accompanies increased cognitive load such as that caused by the auditory tasks. Errors in the visual task increased when the auditory task became more difficult. The increase was greater when the effects of pupillary dilation were blocked by an artificial pupil.

On each trial of a short-term memory task, Ss were required to give the correct response to a paired-associate stimulus and to estimate the number of trials intervening between study and test on that stimulus. On trials where an incorrect paired-associate response was made, judgment of the number of intervening items was relatively independent of the actual number of intervening items. On trials where a correct paired-associate response was made, judgment of the number of intervening items was accurate for recent items but incorrect for more distant items.

Mice were given physostigmine 30 min, 1 day, 3 days, 7 days, or 14 days after brief training in a position habit, which normal animals forget within 14 days. The curve generated by the retention scores at these times was a miniaturization of the curve generated by previous studies using anticholinesterases and prolonged training in a visual task.

In a previous paper (Fraser, 1950) on the relation between angle of display and performance in a prolonged visual task (Mackworth's Clock Test), it was suggested that the presence or absence of the experimenter might affect performance on vigilance tasks. In Mackworth's original experiments (Mackworth, 1950) the subject was in a closed cabinet by himself, and as far as possible all external noise and stimuli were excluded. In the angle of display experiment, the writer sat in the same room as the subject, out of his sight, and there was no particular attempt to exclude the ordinary external noises, etc. It seemed worth while to follow up the previous experiment with another to test the hypothesis that the presence or absence of the experimenter might influence performance in such a task. A new apparatus was devised for this purpose, which possesses some advantages over the Clock Test.

21 high-anxiety and 21 low-anxiety Ss, as designated by the MAS, were tested on a visual acuity task. The stimuli were 33 circles. In some there was a small gap in the perimeter; others were closed. Ss task was to locate the position of the gap. The high-anxiety Ss had a mean error of 11.90 while the low-anxiety Ss had a mean error of 6.43 ( p < .01). These results confirm that high-anxiety Ss make more errors than low-anxiety Ss on a visual task.

A task using plastic geometric objects was designed to study concept identification through the tactile sense. The overall results of this study showed that errors and time to solution were similar in classifying visual and tactile information, but response latency was significantly longer in tactile than in visual concept identification. Also, there is some suggestive evidence that visual concept identification was facilitated with practice on a tactual task, whereas tactual concept identification was not facilitated by practice on a visual task.

TWO separate, though related, conditions may be produced by atomic flash. One is flash blindness, a temporary incapacitation produced by visible light, and the other is retinal burn, produced by a combination of visible and infrared light. Their implications from a disaster standpoint are quite different. Flash blindness is due to the bleaching of the retinal photosensitive chemicals by bright light. The duration of the incapacitation produced depends on the brightness of the items one must see after the flash is over. Hence in daylight this is not a serious problem. The pupils will be smaller and will admit only 1/50th as much light as at night and the visual task will ordinarily be much brighter. There may be a temporary scotoma in the field of vision but unless a burn is produced it will disappear and it is not visually incapacitating. At night visual disability will exist up to

This book is largely a summary of the authors' researches as they deal directly with the problem of reading as a visual task. It is not intended as a volume on reading disabilities or reading difficulties except as they pertain to the physical factors. Of the fifteen chapters, nine are concerned with physical specifications, such as type size, type faces, leading, length of line, papers and inks, duplication materials and illumination intensities, and it is in this field that the authors have made a real contribution. The book is valuable as a source of physical data on reading materials. The discussions are weakest when they enter the physiologic and psychologic fields. A foreword by H. L. Gage, of the Mergenthaler Linotype Company, serves to emphasize the printed material phase of the subject. In any discussion of the tasks involved in prolonged critical seeing, the old arguments concerning the definition and

examine the three stages of reading: matching, coding, and comprehension. Since reading is primarily a visual task, the tests include pictorial processing as well as verbal processing. The seven skills include 1) memory for orientation, 2) coding of temporal sequences to spatial ones, 3) orientation and habituation to novelty, and four tests of comprehension and prediction. The eye movements of the child will be recorded while he is carrying out various verbal tasks, and in other tests the electrical activity of his brain will be recorded as a measure of his attention, comprehension, and prediction.

The purpose of this study was to investigate the relation of the level of illumination intensity to performance and fatigue in visual work. The question of illumination requirements is of considerable importance from the point of view of physiological optics, industrial physiology, and public health. Yet a large part of the research done in the past leaves much to be desired in regard to general approach and specific testing techniques as well as experimental analysis and statistical evaluation. In the present series six illumination levels (2, 5, 15, 50, 100, and 300 footcandles) were studied in repeated experiments in six normal subjects. The work task involved recognition of fine details (letters) and reproduced the essential features of a conveyor inspection operation. In addition to the studying of various criteria of work performance and their change in the course of 2 hours of work, a large battery of visual tests was applied before and after the work so as to characterize the degree of fatigue. Varied illumination affected the performance more than the functional criteria of fatigue. Only one function, the recognition time for stimuli of threshold size, showed a decreasing degree of fatigue up to 300 ft.-c, all other variables, including performance, which changed with a changing level of illumination showed an optimum at 100 ft.-c. The demonstration of an optimum level of illumination makes highly questionable the current practice of recommending “minimum” levels of illumination for industrial jobs, since deterioration of performance and increase in fatigue may result when the optimal level is exceeded. The optimum of 100 ft.-c for the present strenuous visual task is at or below the minimum which should be recommended on the basis of the code of the Illuminating Engineering Society.

Subjects were asked to identify word units within unbroken strings of letters that varied in contextual structure: in Experiment I the strings were first-, third-, and sixth-order approximations to English, and a prose passage; in Experiment II they were ungrammatical, anomalous, and grammatical passages. The subjects in both experiments showed highly significant increments in performance with increasing contextual structure, results that are discussed in terms of word-recognition models postulating distinctive-feature tests. High-speed sequential identification of words in auditory or visual passages is a complex skill that is only beginning to be understood. Neisser (1967) has argued convincingly that these phenomena cannot be explained simply in terms of the successive deciphering of stimulus units. Some type of predictive, hypothesis-generating behavior seems to be involved, in which prior context is used as a basis for inferring properties of material to come. The present research was designed to investigate the use of contextual information for facilitating word prediction in a visual task. There have been several approaches toward defining the ways that contextual cues contribute to word identification. Perhaps the simplest is the probabilistic nature of the material. Miller, Heise, and Lichton (1951) varied the number of alternatives from which an auditory stimulus could be chosen, and found that the larger this set, the less accurate the recognition. Miller and Selfridge (1950) generated a set of passages of varied approximations to English. Their technique involved placing increasing constraints on word selection to force greater conformity to coherent passages. They showed that higher approximations resulted in superior learning. One difficulty of this approach is that higher approximations also show increased semantic and syntactic characteristics, which confounds the interpretation of the results (Tejirian, 1968). Semantic and syntactic features of material have been shown to facilitate word identification in an auditory task using masked presentation. Miller and Isard (1963) developed three types of material: gram

Purpose Detective performance of radiologists for “obvious” targets should be evaluated by visual search task instead of ROC analysis, but visual task have not been applied to radiology studies. The aim of this study was to set up an environment that allows visual search task in radiology, to evaluate its feasibility, and to preliminarily investigate the effect of career on the performance. Materials and methods In a darkroom, ten radiologists were asked to answer the type of lesion by pressing buttons, when images without lesions, with bulla, ground-glass nodule, and solid nodule were randomly presented on a display. Differences in accuracy and reaction times depending on board certification were investigated. Results The visual search task was successfully and feasibly performed. Radiologists were found to have high sensitivity, specificity, positive predictive values and negative predictive values in non-board and board groups. Reaction time was under 1 second for all target types in both groups. Board radiologists were significantly faster in answering for bulla, but there were no significant differences for other targets and values. Conclusion We developed an experimental system that allows visual search experiment in radiology. Reaction time for detection of bulla was shortened with experience.