Visual masking using different test stimulus patterns
Visual masking using different test stimulus patterns - relationship between human visual perception latency and object luminance during high velocity flight
Boyle, R. C.↗
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Stimulus Duration Preference at Electrode Sites Yielding Elicited Behavior
The latency to display eating or drinking during hypothalamic stimulation was compared with the preferred duration of the same stimulus intensity in a self-stimulation situation. All the animals preferred longer stimulus durations than those required to elicit eating or drinking
Cox, V. C.↗
Conceptual design and feasibility evaluation model of a 10 to the 8th power bit oligatomic mass memory. Volume 1: Conceptual design
The oligatomic (mirror) thin film memory technology is a suitable candidate for general purpose spaceborne applications in the post-1975 time frame. Capacities of around 10 to the 8th power bits can be reliably implemented with systems designed around a 335 million bit module. The recommended mode was determined following an investigation of implementation sizes ranging from an 8,000,000 to 100,000,000 bits per module. Cost, power, weight, volume, reliability, maintainability and speed were investigated. The memory includes random access, NDRO, SEC-DED, nonvolatility, and dual interface characteristics. The applications most suitable for the technology are those involving a large capacity with high speed (no latency), nonvolatility, and random accessing.
Recksiedler, A. L.↗
Optimal flash rate and duty cycle for flashing visual indicators.
This experiment examined the ability of observers to determine, as quickly as possible, whether a visual indicator was steadily on or flashing. Six flash rates (periods) were combined factorially with three duty cycles (on-off ratios) to define 18 ?types' of intermittent signals. Experimental sessions were divided into six runs of 100 trials, each run utilizing one of the six flash rates. On any given trial in a run, the probability of a steady signal occurring was 0.5 and the probability of a flashing signal occurring was 0.5. A different duty cycle was employed daily for each experimental session. In all, 400 trials were devoted to each of the flash rates at each duty cycle. Accuracy and latency of response were the dependent variables of interest. The results show that the observers view the light for an interval of time appropriate to the expected flash rate and duty cycle; whether they judge the light to be steady or intermittent depends upon whether the light is extinguished during the predetermined waiting period. Adoption of this temporal criterion delays responding in comparison to those tasks involving responses to light onset. The decision or response criteria held by the observers are also sensitive to the parameters of the flashing light: observers become increasingly willing to call a flashing light ?steady' as flash duration increases.
Markowitz, J.↗
Objective evaluation of cutaneous thermal sensivity
The possibility of obtaining reliable and objective quantitative responses was investigated under conditions where only temperature changes in localized cutaneous areas evoked measurable changes in remote sudomotor activity. Both male and female subjects were studied to evaluate sex difference in thermal sensitivity. The results discussed include: sweat rate responses to contralateral cooling, comparison of sweat rate responses between men and women to contralateral cooling, influence of the menstrual cycle on the sweat rate responses to contralateral cooling, comparison of threshold of sweating responses between men and women, and correlation of latency to threshold for whole body sweating. It is concluded that the quantitative aspects of the reflex response is affected by both the density and activation of receptors as well as the rate of heat loss; men responded 8-10% more frequently than women to thermode cooling, the magnitude of responses being greater for men; and women responded 7-9% more frequently to thermode cooling on day 1 of menstruation, as compared to day 15.
Vanbeaumont, W.↗
Cortical potentials evoked by confirming and disconfirming feedback following an auditory discrimination.
Vertex potentials elicited by visual feedback signals following an auditory intensity discrimination have been studied with eight subjects. Feedback signals which confirmed the prior sensory decision elicited small P3s, while disconfirming feedback elicited P3s that were larger. On the average, the latency of P3 was also found to increase with increasing disparity between the judgment and the feedback information. These effects were part of an overall dichotomy in wave shape following confirming vs disconfirming feedback. These findings are incorporated in a general model of the role of P3 in perceptual decision making.
Squires, K. C.↗
Adjustment of saccade characteristics during head movements.
Saccade characteristics have been studied during coordinated eye-head movements in monkeys. Amplitude, duration, and peak velocity of saccades with head turning were compared with saccades executed while the head was artificially restrained. The results indicate that the saccade characteristics are modulated as a function of head movement, hence the gaze movement (eye+head) exactly matches saccades with head fixed. Saccade modulation is achieved by way of negative vestibulo-ocular feedback. The neck proprioceptors, because of their longer latency, are effective only if the head starts moving prior to the onset of saccade. It is concluded that saccades make with head turning are not 'ballistic' movements because their trajectory is not entirely predetermined by a central command.
Morasso, P.↗
Sleep-monitoring, experiment M133
The Skylab sleep-monitoring experiment simulated the timelines and environment expected during a 56-day Skylab mission. Two crewmembers utilized the data acquisition and analysis hardware, and their sleep characteristics were studied in an online fashion during a number of all night recording sessions. Comparison of the results of online automatic analysis with those of postmission visual data analysis was favorable, confirming the feasibility of obtaining reliable objective information concerning sleep characteristics during the Skylab missions. One crewmember exhibited definite changes in certain sleep characteristics (e.g., increased sleep latency, increased time Awake during first third of night, and decreased total sleep time) during the mission.
Frost, J. D., Jr.↗
The solution of large multi-dimensional Poisson problems
The Buneman algorithm for solving Poisson problems can be adapted to solve large Poisson problems on computers with a rotating drum memory so that the computation is done with very little time lost due to rotational latency of the drum.
Stone, H. S.↗
Vertex potentials evoked during auditory signal detection - Relation to decision criteria
Vertex potentials were recorded from eight subjects performing in an auditory threshold detection task with rating scale responses. The amplitudes and latencies of both the N1 and the late positive (P3) components were found to vary systematically with the criterion level of the decision. These changes in the waveshape of the N1 component were comparable to those produced by varying the signal intensity in a passive condition, but the late positive component in the active task was not similarly related to the passively evoked P2 component. It was suggested that the N1 and P3 components represent distinctive aspects of the decision process, with N1 signifying the quantity of signal information received and P3 reflecting the certainty of the decision based upon that information.
Squires, K. C.↗
Regularity in the control of the free-running sleep-wakefulness rhythm
In the present experiment, rigid control over the sleep and wake-up times was employed in an attempt to contain the natural rhythm to a 24-hr cycle. Eight subjects were isolated from all time and social cues for 10 days. They were placed on a rigid schedule of sleep between 11 p.m. and 7 a.m. The results indicate that, for practical purposes, the free-running sleep-wakefulness rhythm can be contained to a 24-hr cycle by rigid control of the sleep portion of the cycle. When part of the control was released by allowing the subjects to sleep beyond 7 a.m., they slept an average of 67 min longer and showed sleep latencies which averaged 73 min. From these data it is concluded that control of the sleep portion of the sleep-wakefulness cycle, particularly control of the wake-up time, is sufficient to contain the free-running sleep-wakefulness rhythm to a 24-hr cycle.
Webb, W. B.↗
The effect of a visual indicator on rate of visual search Evidence for processing control
Search rates were estimated from response latencies in a visual search task of the type used by Atkinson et al. (1969), in which a subject searches a small set of letters to determine the presence or absence of a predesignated target. Half of the visual displays contained a marker above one of the letters. The marked letter was the only one that had to be checked to determine whether or not the display contained the target. The presence of a marker in a display significantly increased the estimated rate of search, but the data clearly indicated that subjects did not restrict processing to the marked item. Letters in the vicinity of the marker were also processed. These results were interpreted as showing that subjects are able to exercise some degree of control over the search process in this type of task.
Holmgren, J. E.↗
Responses evoked from man by acoustic stimulation
Clicks and other acoustic stimuli evoke time-locked responses from the brain of man. The properties of the waves recordable within the interval from 1 to 10 msec after the stimuli strike the eardrum are discussed along with factors influencing the waves in the 100 to 500 msec epoch. So-called brainstem responses from a normal young adult are considered. No waves were observed for clicks to weak to be heard. With increasing stimulus strength the waves become larger in amplitude and their latency shortens.
Galambos, R.↗
On hemispheric differences in evoked potentials to speech stimuli
Confirmation is provided for the belief that evoked potentials may reflect differences in hemispheric functioning that are marginal at best. Subjects were right-handed and audiologically normal men and women, and responses were recorded using standard EEG techniques. Subjects were instructed to listen for the targets while laying in a darkened sound booth. Different stimuli, speech and tone signals, were used. Speech sounds were shown to evoke a response pattern that resembles that to tone or clicks. Analysis of variances on peak amplitude and latency measures showed no significant differences between hemispheres, however, a Wilcoxon test showed significant differences in hemispheres for certain target tasks.
Galambos, R.↗
Study and response time for the visual recognition of 'similarity' and identity
Four subjects compared successively presented pairs of line patterns for a match between any lines in the pattern (similarity) and for a match between all lines (identity). The encoding or study times for pattern recognition from immediate memory and the latency in responses to comparison stimuli were examined. Qualitative differences within and between subjects were most evident in study times.
Derks, P. L.↗
Visual search in a forced-choice paradigm
The processing of visual information was investigated in the context of two visual search tasks. The first was a forced-choice task in which one of two alternative letters appeared in a visual display of from one to five letters. The second task included trials on which neither of the two alternatives was present in the display. Search rates were estimated from the slopes of best linear fits to response latencies plotted as a function of the number of items in the visual display. These rates were found to be much slower than those estimated in yes-no search tasks. This result was interpreted as indicating that the processes underlying visual search in yes-no and forced-choice tasks are not the same.
Holmgren, J. E.↗
The Skylab sleep monitoring experiment - Methodology and initial results
The sleep monitoring experiment permitted an objective evaluation of sleep characteristics during the first two manned Skylab flights. Hardware located onboard the spacecraft accomplished data acquisition, analysis, and preservation, thereby permitting near-real-time evaluation of sleep during the flights and more detailed postmission analysis. The crewman studied during the 28-Day Mission showed some decrease in total sleep time and an increase in the percentage of Stage 4 sleep, while the subject in the 59-Day Mission exhibited little change in total sleep time and a small decrease in Stage 4 and REM sleep. Some disruption of sleep characteristics was seen in the final days of both missions, and both subjects exhibited decreases in REM-onset latency in the immediate postflight period. The relatively minor changes seen were not of the type nor magnitude which might be expected to be associated with significant degradation of performance capability.
Frost, J. D., Jr.↗
Selective attention and the auditory vertex potential. 1: Effects of stimulus delivery rate
Enhancement of the auditory vertex potentials with selective attention to dichotically presented tone pips was found to be critically sensitive to the range of inter-stimulus intervals in use. Only at the shortest intervals was a clear-cut enhancement of the latency component to stimuli observed for the attended ear.
Schwent, V. L.↗