Michel Loeb

Variation in performance on auditory and visual monitoring tasks as a function of signal and stimulus frequencies

Observers were required to detect double jumps of a diffuse light spot jumping in a circular pattern and more intense noise pulses in a pulse train. Seven groups performed at different combinations of stimulus and signal frequencies, higher signal frequency/stimulus frequency ratios, and lower stimulus frequencies. Stimulus frequency was a more potent determiner of performance than signal frequency, and performance was not invariant within a given signal frequency/stimulus frequency ratio. Correlations of dependent measures were also examined.-Results are discussed with reference to various theories of vigilance behavior.

SENSE MODE AND COUPLING IN A VIGILANCE TASK

Usarmymedical Research Laboratory, Fort Knox, Kentucky This investigation examined the performance of 36 Ss on three 90-min vigilance tasks. As time on task increased, there was a significant decrease in number of detections and false responses and a corresponding significant increase in response latency. The consistent rank order relationship between stimulus conditions suggests that there were uniform trends among these conventional response measures. There was a significant decline in sensitivity (d′) lor the closely coupled tasks, regardless of the sense mode involved. However, d′ remained fairly stable for the loosely coupled visual task. The significant increase in criterion values(β) suggest that Ss adopt a more conservative mode of responding with increasing time on task. Further, these data indicate that a lack of control of coupling effects, rather than sense mode specificity, may have confounded the interpretation of prior research on visualand auditory tasks.

Noise stress and circadian arousal in self-paced computation

Previous work(Frankenhaeuser & Lundberg, 1977) has shown that unpaced mental arithmetic is performed at slower rates in noise, despite unchanged catecholamine indices of arousal; only male subjects were used, tested early in the day. Since the times of testing entail arousal effects that interact with noise stress, and the sex of subject further modifies these interactions, a new experiment was designed to include these variables. Men and women were tested on the Norinder mental arithmetic task, in quiet or in noise, either in the morning, when arousal was low, or during the early evening, when temperature curves indicate that arousal should be high. Analysis of the number of problems attempted shows a significant drop for men in noise in the morning, but an interaction due to reversal of the noise effect in the evening; there is no main effect of noise when womens scores are included. The results are compatible with interpretations combining motivation and cognition, and they demonstrate the importance of the experimental variables in explaining noise stress effects.

VIGILANCE FOR AUDITORY INTENSITY CHANGES AS A FUNCTION OF PRELIMINARY FEEDBACK AND CONFIDENCE LEVEL.

Forty-eight subjects were asked to respond to occasional increments in a pulse train with ratings of certainty of signal occurrence for 20 min. Half (F) subjects were given feedback; half (NF) were not. In a second session all responded during an 80 min period with a simple response. In another, half responded with certainty ratings; half responded with a simple response. Finally, those who had responded with ratings responded simply and those who had employed a simple response made ratings. It was found that F subjects made fewer false responses and tended to make fewer detections in earlier sessions. In later sessions false responses were reduced for all. The usual progressive false response and detection reductions and latency increases were noted; when subjects employed ratings reductions in certainty were noted within sessions. It was concluded that the data support the detection theory model for vigilance for this type of task.

Noise, sex and time of day effects in a mathematics task.

Abstract A pilot experiment explored the effects of list length (four, six or eight digits) and presentation rate (1-6.5 per second) in a task of computer-paced addition. As the experimental variables changed, men tended to vary their speed of response while women tended to vary their level of accuracy. Conditions selected from the first experiment (six digits at two and four per second) were employed in a second, with the object of examining interactions among noise, time of day and sex. Practice effects over three sessions of testing confirmed the sex difference in speed-accuracy strategies. Male and female performance tended to change between the a.m. and p.m. test periods, such that women in quiet behaved similarly to men in noise, showing poorer p.m. performance in terms of response times and non-responses, but fewer commissive errors. Although the effects of circadian arousal were varied, noise consistently produced an effect different from that of time of day. A complex model, supported by more fac...

A comparison of auditory monitoring performance in blind subjects with that of sighted subjects in light and dark

Two experiments were performed in which blind Ss, sighted Ss working in the dark, and sighted Ss working in the light were compared as to their efficiency on an auditory watchkeeping task. Absolute and differential auditory thresholds were measured in both experiments, and in the second experiment the groups also underwent a signal detection session under alerted conditions. There was some inconsistency as to relative performance of the sighted groups, but in both experiments the blind Ss were superior on the auditory watchkeeping task as to signals detected and effective sensitivity (d’). 1 This difference was not attributable to a difference in auditory sensitivity or to a criterion adopted for

An Update of Findings Regarding Vigilance and a Reconsideration of Underlying Mechanisms

The effects of numerous display, task, and organismic variables known to influence monitoring behaviors are reviewed, and the principal models or theories to explain such behaviors are assessed in light of the empirical findings. The current status of vigilance theories in the mid-1970s is summarized as follows: (1) Recent research, like previous research, has failed to confirm any one theory exclusively, (2) the data available continue to cast doubt on the prospect of any current theories being able to account adequately for all established vigilance phenomena, (3) the differentiation of “cortical arousal” may provide a basis for a useful advance in an arousal-theory explanation of some monitoring phenomena, especially as related to certain brain-wave activities, and (4) other factors not encompassed by any of the theories are known to affect vigilance, some of them to appreciable extents.

Noise Exposure, Monitoring and Tracking Performance as a Function of Signal Bias and Task Priority

Abstract An experiment was conducted to extend some findings reported by Hockey (1970 a, b) who employed a primary tracking and secondary watchkeeping task. He found that when signals were more probable in the centre and subjects were asked to perform a central tracking task, they missed peripheral signals while in noise. When signals were equally probable at all loci this effect did not occur. Hockey concluded that the effect reflects a funnelling of attention rather than of vision. In the present experiment similar tracking and watchkeeping tasks were employed, but for separate groups either the watchkeeping or tracking was primary and the other task secondary. In the primary tracking group there was a subgroup for which signal probability was higher in the centre and one in which there was no bias; for the primary watchkeeping group there was a subgroup for which signal probability was higher in the periphery and a subgroup for which there was no bias. In each subgroup there were 12 subjects, who perfo...

Influence of noise characteristics on behavioral aftereffects.

Two experiments were performed which were designed to replicate and extend the findings of Glass and Singer and others on the aftereffects of noise on performance. In the first, subjects were exposed to 24 min of 95 dBA fixed schedule (FS) or random schedule (RS) intermittent conglomerate noise or to 46 dBA background control (C) noise. After exposure. persistence on insoluble puzzles was least in the RS noise condition and greatest in the C noise condition. In the second experiment. subjects were exposed to 95-dBA intermittent white noise. Recorded nonnal aircraft flyovers, recorded combinations of aircraft noise peaks (AC), and Glass and Singer (GS) conglomerate noise or to 48-dBA background control noise. Following exposure, the GS and AC groups persisted less on the puzzles than the other three groups. In neither experiment was there an effect of noise on routine tasks performed during exposure or on a proofreading task following exposure. Also, there were no significant correlations between subjective ratings of the noise and the performance aftereffects. The significance of these findings is considered ill terms of existing theories.

Backward interference by tones or noise in pitch perception as a function of practice

In a first experiment, the identification of brief tonal stimuli was unaffected by subsequent presentation of white noise. However, subsequent pure tones, whether central to the stimulus frequencies or remote from them, caused substantial declines in correct identification. Apparent backward masking seems therefore to follow rather than to precede some degree of categorization of the masking stimulus. A second experiment shows that even these effects are temporary. Early masking effects are heavily modified by practice, and are not therefore permanent features of sensory processing. Neither experiment provides support for preperceptual theory.