The topology of performance curves during 72 hours of sleep loss: A memory and search task

Three levels of working memory load of a visual search (Memory and Search) task were tested in a 72-hour sleep deprivation paradigm. General performance and accuracy decrease over time with monotonic and rhythmic components. The signal detection discriminability index, d', decreases monotonically with rhythmic variations. The index of response bias, β, shows no monotonic trend, but significant circadian rhythmicity. The extent of the monotonic and rhythmic changes in accuracy and in d' is directly related to the level of working memory load. The amplitude of the circadian component of accuracy and d' is enhanced for the higher levels of working memory load. The implication of potentiated circadian rhythmicity as a function of cumulative sleep loss is discussed.     

Attention to pure tones

Listeners were required to detect increments of intensity or frequency in trains of pure tone bursts under different conditions of attention. The data were analysed taking into account contralateral events when more than one stimulus train was present. Marked changes in d' and β were found and the changes were positively correlated.

If targets are rare and attention is divided the values of β and d' are the same as in undivided attention provided that the contralateral event is a correct rejection, but fall if the contralateral events are hits or false alarms. If targets and non-targets are equi-probable no such difference is found. The data suggest that the observers can make use of the statistical properties of the stimulus sources. The results are compared with those in recent experiments using pure tones in a discrete trial paradigm and in experiments using semantic stimuli.     

Acoustic similarity and interference in short-term recognition memory: Some results of a decision-theory analysis

The following three studies of single-probe recognition memory set out to show the effect on the signal-detectability measures of d' and β (Tanner and Swets, 1954) of variations in the acoustic similarity of interfering material, which may either precede or follow the item to be remembered (proactive or retroactive interference --PI or RI). The first experiment studies a situation employed by Wickelgren (1966a), who reported that acoustically similar RI substantially reduced d'. It is shown that this effect could have been due to biases in Wickelgren's original designs, and that when a bias-free design is used, the fall in d' is only of borderline significance.

To investigate this problem further, a design was evolved in which two items were presented for memorizing, which varied in acoustic similarity to each other, and (after a distracting task) a probe was presented with one of three questions: Was this the first item of the pair? Was it the second? or, Did it occur in either position? In the first case, recognition-memory with RI of varying acoustic similarity was being studied, and as in the first experiment, it was found that similarity slightly reduced d'. With the second question, PI effects were being studied, and here negligible differences were found. With the third type of question, a “location-free” test, no effects of similarity were found. The last result rules out Posner's (1967) “acid-bath” explanation of similarity effects in interference: an explanation in terms of “differentiation” (or “filtering”) was also invalidated by the results of a third experiment, in which the same effects were found even though similarity varied only between stimulus items and interference, and not between these and the probe. Wickelgren's (1966b) associative model appears to have least difficulty in accommodating these results, though even this needs certain ad hoc assumptions to be able to do so.     

Recognition assessed by D' and by a non-parametric alternative (the A-index) as a function of the number of choices

Freedom from restrictive assumptions and ease of psychological interpretation are two basic criteria for a satisfactory measure of recognition performance. The A-index (Brown, 1965a) comes close to fulfilling these criteria. It is based on the proportion of wrong choices rejected in a multi-choice test as revealed by the number of choices required to select the correct choice. It can be transformed into the d' measure of signal detection theory (SDT) if the standard assumptions of this theory hold, but not in general. Two experiments on the recognition of words-in-noise are described. In the first there were 3, 5, 8 or 16 choices. They were typed on a card which was displayed to the listener during the presentation of a word. On both measures 5-, 8- and 16-choice recognition did not differ significantly, while 3-choice recognition was slightly, but significantly, superior. The second experiment concerned the effect of delaying the display of the card until 2 sec. after presentation. No evidence for an effect was obtained. In both experiments, there was suggestive but not conclusive evidence that the d' measure tended to overestimate recognition efficiency.     

Measurement of trace strength in memory for pictures

Four experiments using a yes-no recognition task with snapshots examined (1) the effect of presenting not one but two items simultaneously, either both targets or both distractors, for a single judgment at a retention test trial; (2) the rate of forgetting; (3) the interaction between retention interval and the exposure duration at acquisition; (4) acquisition as a function of the number of times a picture was presented. In each case performance was assessed by calculating the discriminability index d'. The results supported the hypotheses that trace strength is lognormally distributed, that forgetting is exponential, and that in acquisition trace strength is a linear function of the number of presentations.     

Contextual assimilation and its effect on the division of attention between nonverbal signals

Subjects performed a recognition task in which a low or a high frequency signal was presented simultaneously with a dim or a bright intensity one. The independent variable was the degree of association between the signals on the two dimensions. Unknown to the subjects four levels were tested in separate conditions, 1.0, 0.8, 0.5 and 0.2. Increasing the positive association improved overall sensitivity as measured by d' on both dimensions, but left contingent sensitivity unchanged. Changing the association did not affect overall bias, as measured by Beta. However, holding context constant by analysis produced significant differences between individual measures of contingent bias in the direction of assimilation, for example “low” responses tended to accompany dim signals and “dim” responses. The differences were unaffected by the changes in association. The results are interpreted as favouring models of contextual assimilation which assume that biasing at some level of processing depends upon the mutually contingent interaction of discrete events rather than on memory and expectation of the relative frequency of conjoint events. Further support for this conclusion comes from previous studies which indicate that assimilation occurs with separate responses but not with unitary ones. The implications of the findings for research on the division of attention are discussed, particularly the need to control variability in measured bias to establish a true change in the allocation of attention. Two generalized models of contextual assimilation are proposed, one based on “object” and the other on “lexical” assimilation. The possible application of these models to synaesthesia is considered.     

Lack of degradation in visuospatial perception of line orientation after one night of sleep loss

Sleep deprivation impairs a variety of cognitive abilities including vigilance, attention, and executive function. Although sleep loss has been shown to impair tasks requiring visual attention and spatial perception, it is not clear whether these deficits are exclusively a function of reduced attention and vigilance or if there are also alterations in visuospatial perception. Visuospatial perception and sustained vigilance performance were therefore examined in 54 healthy volunteers at rested baseline and again after one night of sleep deprivation using the Judgment of Line Orientation Test and a computerized test of psychomotor vigilance. Whereas psychomotor vigilance declined significantly from baseline to sleep-deprived testing, scores on the Judgment of Line Orientation did not change significantly. Results suggest that documented performance deficits associated with sleep loss are unlikely to be the result of dysfunction within systems of the brain responsible for simple visuospatial perception and processing of line angles.     

From Mackworth’s clock to the open road: A literature review on driver vigilance task operationalization

ObjectiveThis review aimed to characterize tasks applied in driving research, in terms of instructions/conditions, signal types/rates, and component features in comparison to the classic vigilance literature.BackgroundDriver state monitoring is facing increased attention with evolving vehicle automation, and real-time assessment of driver vigilance could provide widespread value across various levels (e.g., from monitoring the alertness of manual drivers to verifications of readiness in transitions of control between automated and manual driving). However, task requirement comparisons between the classic vigilance research and vigilance in car driving have not to date been systematically conducted.MethodThis study decomposed the highest-cited vigilance literature of each full decade since the 1940s for the situational features of the renowned vigilance decrement phenomenon originating from Mackworth (1948). A consensus set of 18 different situational features was compiled and included for example an (1) isolated (2) subject … perceiving (3) rare (4) signals … against (10) frequent (11) noise … in a (17) prolonged (18) task. Next, we reviewed 69 experimental vigilance task operationalizations (i.e., required signal detection and response) within 39 publications concerned with driving vigilance. All vigilance tasks were coded as “driving vigilance tasks” or “non-driving vigilance tasks” based on the perceptual signal and response action both belonging to normal driving activity or not. Presence, absence, and unreported presence/absence of each of the 18 features was rated for each task respectively as “overlap”, “contrary”, and “unspecified”. In conjunction, instructions/environmental conditions, signal definitions, signal rates, and summaries of the experimental vigilance tasks were extracted.ResultsA majority of driving vigilance tasks was performed in simulators (69%) compared to on-road (28%) and watching videos (3%) along with large differences in task conditions. Participants had to maintain fixed speed/lane positions in the simulators in higher proportion (74%) than on the road (36%) where they had only to drive “normally” and/or by loose conventions like “according to the law” more often (55% versus 15%). Additionally, presence of other traffic was found more often on-road (91%) than in simulators (48%). A specification of signals to detect and react to was found present within/for driving less often (59%) than alongside/in conjunction with driving (100%). Likewise, rates of signals (i.e., frequency of signal occurrence) were reported more often for non-driving vigilance tasks (80%) than in driving vigilance tasks (21%). For driving vigilance tasks, the highest overlap was 12 of the 18 features present (67%). On average, results showed relatively low levels of classic feature overlap (36%) with high rates of unspecified feature presence (46%) for driving vigilance tasks compared to non-driving vigilance tasks with higher classic feature overlap (64%) and fewer features unspecified (13%).Conclusion and applicationThere is little overlap between the well-known and often cited vigilance decrement phenomenon and published experimental tasks of driving vigilance. Major differences were also found in the instructions/environmental conditions of simulator versus on-road experimental driving vigilance tasks. What driving vigilance practically is in the real-world thus remains a promising area for future research. We recommend that researchers apply approaches which account for more real-world driving features to better expose and address uncertainty regarding driving and vigilance.     

A test of current explanations of the effect of item familiarity on memory

The effects of item familiarity in memory have been variously ascribed to differences in storage or retrieval efficiency, response availability, and response bias. The experiments reported here attempted to discriminate between these explanations, using a model of the response process based on signal-detection theory. Memory for English surnames varying in frequency of occurrence was tested under free recall and recognition conditions. In both conditions, common names appeared more often among the incorrect responses, reflecting a response bias in their favour; but storage and/or retrieval of these names, as measured by the parameter d', was less efficient than for uncommon ones. The finding of similar results in recognition and recall shows that the effect remains even when differences in response availability are removed by the use of a probe.     

The multiple vigilance test

The multiple vigilance test is a 30-min signal detection task designed to assess performance. Sixty target and 180 nontarget stimuli are presented with random interstimulus intervals ranging from 4 to 11 sec. Subjects respond by pressing the spacebar (or microswitch in an alternate version of the program) when they see the masking pattern transformed into the target. This vigilance test is used in conjunction with measures of physiological sleepiness (Multiple Sleep Latency Test) and subjective sleepiness (Stanford Sleepiness Scale). This behavioral information concerning manifest sleepiness provides a more complete picture of a subject’s state of alertness. The assessment of vigilance during long, monotonous, nonstimulating tasks is clinically important in patients with disorders of sleep and arousal.     

Auditory signal detectability as a function of pre-experimental shock

A neurotic, schizophrenic and normal control group detected a 1,000 cps. 2 sec. tone with an a priori probability of occurrence of 0.5 against a background of continuous white noise during a specified 4 sec. interval. An index of signal detectability, dprime;, and a decision criterion, β, were calculated from the YES-NO responses for 150 control trials, and 150 trials which were preceded by free electric shock at maximum tolerance level. The results show a decrement in signals detected for the neurotic and schizophrenic group as compared to the normal control, whose detection rate improved significantly. The decision criterion remained unaffected.     

The effects of changing the phase and duration of sleep.

The relative effects of extended sleep, reduced sleep, and shifts of habitual sleep time on subsequent performance and mood were studied. Ten healthy male university students who regularly sleep 9.5-10.5 hr were the subjects. Measurements were obtained from a 45-min auditory vigilance task, a 5-min experimenter-paced addition task and a mood adjective check list 30 min after awakening, at midday, and in the evening following five electroencephalographically recorded nights of sleep. The experimental treatments compromised at 9.5-10.5 hr habitual sleep condition and four conditions in which the regular sleep period was lengthened, reduced, delayed, and advanced by 3hr. Following each 3-hr altered condition of sleep there was an equivalent decline in vigilance performance and in subjective arousal as measured by the mood scales. Together with other recent evidence, the present results support the hypothesis that acute disruption of the 24-hr sleep-wakefulness cycle produces degradations in human performance largely independent of total sleep time.     

CRT信号显示的刺激率和信号率对警觉作业的影响

本实验系统地考察了在不同刺激率、信号率条件下警觉水平的变化 ,并分析了以往警觉理论的适应条件。实验一采用 5次 /分、1 5次 /分和 30次 /分的刺激率条件 ,发现检测正确率在各条件下随时间的变化是由于 d′下降所致 ,而β值基本不变 ,可以认为警觉随时间下降是由于疲劳所致 ;中等刺激率条件下的 d′最高 ,低刺激率次之 ,高刺激率最差并且高刺激率导致被试唤醒水平降低。实验二在 30次 /分的高刺激率条件下变化信号率 (分别为 3次 /分、6次 /分和 1 2次 /分 ) ,发现信号率变化不会改变 d′,但导致β值的变化 ,可以认为高信噪比导致被试的唤醒水平升高     

Effects of anxiety on attentional allocation and task performance: An information processing analysis

An information processing signal detection methodology was employed to examine attentional allocation and its correlates in both normal comparison (NC) and generalized anxiety disorder (GAD) participants. In particular, the impact of neutral distractor and negative feedback cues on performance of an attention vigilance task was investigated. Individuals with GAD (N = 15) evidenced impaired performance on an attention vigilance task relative to NC participants (N = 15) when neutral distractor cues were presented. Contrary to prediction, no group differences in performance were detected under conditions in which participants were presented negative feedback cues they were told were relevant to their performance. Instead, GAD participants exhibited improvement during the experimental task such that their performance was equivalent to NC participants. Across trials, the clinically anxious group endorsed significantly higher levels of worry and negative affectivity; however, they failed to respond with concomitant physical arousal (e.g. increased muscle tension). These data are discussed within the context of Eysenck and Calvo's (1992, Cognition and Emotion, 6, 409–434) processing efficiency theory. Additionally, the results of this investigation provide support for Barlow's (1988, Anxiety and its disorders: The nature and treatment of anxiety and panic) conceptualization of anxiety as requiring the interaction of cognitive schema and physiological arousal.     

The effect of lack of sleep on visual watch-keeping

Sixteen subjects performed a test of visual watch-keeping twice, at the same hour of the same day of successive weeks. The test lasted 40 min. On one of these occasions the test was done after normal sleep the previous night; signals were detected at a steady rate throughout. On the other occasion the subjects had no sleep the previous night; they passed the time in innocuous leisure activities. Here a similar level of performance was maintained for the first 20 min. of the test. After this the rate of signal detection declined steadily. In the final quarter of the test the rate was roughly one third that of the first quarter.

Signals missed were divided into three categories, (u) signals missed while watching the display, (b) signals missed while not watching, and, (c) signals missed while asleep. Lack of sleep produced increases in all three of these categories.

These results support previous suggestions that a test has to be prolonged before performance is affected by moderate loss of sleep; they also suggest that it is the simpler, or perhaps the more predictable, tests which are more affected.     

Sustained Attention and Unintentional Injury Among Preschool-Aged Children

This study examined vigilance in preschool-aged children and explored the relationship between vigilance and unintentional injury. There were 28 participating children, aged 4 and 5 years, who completed a computerized vigilance task for two 5-min sessions. The task generated measures of correct detections, false alarms, reaction time, and the signal detection indices of d ' and c. Primary caregivers completed daily injury phone journals for a 4-week period. Results indicated that age and signal probability affected vigilance. Older children made more correct detections, had greater perceptual sensitivity, and performed in patterns similar to adults. Performance was enhanced in the high signal probability condition. In addition, vigilance indicators of perceptual sensitivity and response bias were predictive of injury, while age was not. Specifically, children with lower perceptual sensitivity scores, and who were less responsive to the vigilance task, experienced more unintentional injures over the course of the study.     

Signal frequency and shock probability as determinants of prolonged vigilance performance in rhesus monkeys

The effects of changing signal frequency on a prolonged vigilance task were investigated by systematically increasing the average inter-trial interval between successive signals. During a 6-hr watch, vigilance performance remained constant when the rate of signal presentation was 40, 20, and 10 per hour. When the rate of signal presentation was reduced to 7 or 4 per hour, marked decrements in detection performance were observed. Similar vigilance decrements occurred when the average rate of signals per hour was kept constant (10 per hour) and the probability of receiving a shock for missing a signal was systematically varied. The results of this study indicate the importance of reinforcement factors in the control and maintenance of vigilance performance.     

Cognitive performance during successive sustained physical work episodes

The effects of physical work (30% of \(\dot VO_2 \) max), sleep loss (3-h nap during a 48-h operation), continuous work (CW), and time of day on cognitive performance were assessed (by ANOVA) in this repeated-measures study comparing two groups (exercise/nonexercise) of healthy young men (N=22). Treadmill walking did not accentuate or attenuate sleep loss effects on performance; however, sleep loss alone did degrade visual vigilance and memory for words. Time-of-day fluctuations were found in choice reaction time, logical reasoning, and word memory. Visual vigilance for nonexercising subjects degraded sooner on the 2nd CW day than it did for exercising subjects. A 3-h nap at 0400 h after 1 17-h CW day was not immediately recuperative. These findings indicate that exercise at 30% of \(\dot VO_2 \) max does not compound sleep-loss effects in cognitive performance. Indeed, physical activity during video terminal monitoring may delay any sleep-loss decrement. Variability of many cognitive abilities throughout the day appeared to show a greater effect than the sleep-loss and exercise effects over 2 days.     

Effects of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance: comparison of horizontal and 6 degrees head-down bed rest

This study examined the effect of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance. Each of 7 volunteers were maintained for 3 days of head-down and horizontal bed rest in a counter-balanced design. Assessment measures were polysomnographic recordings on the first night and performance on psychophysiological tasks on the second day involving subjective and objective vigilance, P300, simple reaction time tasks, and dual performance tasks. No clear difference in sleep structure was observed between the head-down and horizontal conditions, except for a slight decrease in Stage 4 for head-down. Both subjective and objective daytime vigilance, P300, and the simple RT task showed no statistical difference, although tracking performance on the dual task showed deterioration at 10:00 for the head-down condition. These results suggest that nocturnal sleep, daytime vigilance, and psychophysiological functions were not disturbed in head-down sleep conditions, although there was a mild deterioration of higher attentional function in the morning.     

Poor recall of eye-movement signals from Stage 2 compared to REM sleep: implications for models of dreaming

An ongoing assumption made by sleep researchers is that since dreams are more often recalled on awakening from rapid eye movement (REM) sleep, dreams must occur more often during this stage of sleep. An alternative hypothesis is that cognition occurs throughout sleep, but the recall of this mentation differs on awakening. When a dream is not reported on awakening, there is no method of establishing whether it did not happen or was forgotten. The aim of the present study was to investigate this issue using an eye movement (EM) signal verification technique. Participants were instructed to produce an EM signal whenever they heard a tone. Tones were presented at increasing volume during Stage 2 and REM sleep until EM signal verification was observed. Ninety seconds after signal verification, participants were awakened and asked if they remembered hearing the tone or responding with the EM signal. Such recollection of signal verified tone (SVT) presentations was significantly less after Stage 2 sleep (65%) compared to REM sleep (100%) presentations. Furthermore, SVT recall was significantly correlated with reported dream recall frequency, suggesting the same processes involved in recalling SVTs might also underlie dream recall.