Detection of auditory signals presented at random times

One hundred msec tones of 1000 Hz at four intensities were presented according to two Poisson schedules in a background of wide band noise and as increments to a 1000 Hz tone. Each 15 minute test session was run under fixed conditions and one of three instructions to detect the signals; the two Ss were free to respond at any time. The data analyzed were several inter-response and signal-response distributions, and they were compared with a theory due to Luce. Discrepancies between the theory and data indicate needed modifications of both the theory and the procedure.     

Detection of auditory signals presented at random times: III

Reaction times to a pure tone in noise were measured. Throughout, the time from the warning signal to the reaction signal was exponentially distributed, and the signal was response terminated. Response criterion, signal intensity, and mean foreperiod wait were varied. A model that assumes a Poisson sensory transduction, a pulse-activated decision process, and an additive bounded residual process was tested. It was concluded that the assumed decision process was in error. Among the empirical results, the dependence of mean reaction time on signal waits was shown to depend largely on the average wait, not the actual one, and that this relationship between mean reaction time and average stimulus wait increased for strong signals and decreased for weak ones.     

Detection of auditory signals occurring at random times: Intensity and duration

Observers attempted to detect a weak auditory signal presented in noise. The onset of the signal was determined by a Poisson process, and only responses occurring 1 sec after signal onset were considered detections. Three latency distributions were measured, the time to a signal onset, the reaction time distribution, and the false-alarm distribution (of responses occurring before a signal onset). A simple two-state model is proposed to account for a discrepancy between the distribution of signal waits and the distribution of false alarms. The hazard functions of the reaction time distributions are considered in detail and a simple accumulation model is proposed to account for the results.     

Short-term memory for simultaneously presented visual and auditory signals in the pigeon

A series of divided-attention experiments in which matching to the visual or auditory component of a tone-light compound was compared with matching to visual or auditory elements as sample stimuli were carried out. In 0-s delayed and simultaneous matching procedures, pigeons were able to match visual signals equally well when presented alone or with a tone; tones were matched at a substantially lower level of accuracy when presented with light signals than when presented as elements. In further experiments, it was demonstrated that the interfering effect of a signal light on tone matching was not related to the signaling value of the light, and that the prior presentation of light proactively interfered with auditory delayed matching. These findings indicate a divided attention process in which auditory processing is strongly inhibited in the presence of visual signals.     

Processing of visually presented clock times

The encoding and representation of visually presented clock times was investigated in three experiments utilizing a comparative judgment task. Experiment 1 explored the effects of comparing times presented in different formats (clock face, digit, or word), and Experiment 2 examined angular distance effects created by varying positions of the hands on clock faces. In Experiment 3, encoding and processing differences between clock faces and digitally presented times were directly measured. Same/different reactions to digitally presented times were faster than to times presented on a clock face, and this format effect was found to be a result of differences in processing that occurred after encoding. Angular separation also had a limited effect on processing. The findings are interpreted within the framework of theories that refer to the importance of representational codes. The applicability to the data of Bank's semantic-coding theory, Paivio's dual-coding theory, and the levels-of-processing view of memory are discussed.     

The integration of auditory and visual motion signals at threshold

To interpret our environment, we integrate information from all our senses. For moving objects, auditory and visual motion signals are correlated and provide information about the speed and the direction of the moving object. We investigated at what level the auditory and the visual modalities interact and whether the human brain integrates only motion signals that are ecologically valid. We found that the sensitivity for identifying motion was improved when motion signals were provided in both modalities. This improvement in sensitivity can be explained by probability summation. That is, auditory and visual stimuli are combined at a decision level, after the stimuli have been processed independently in the auditory and the visual pathways. Furthermore, this integration is direction blind and is not restricted to ecologically valid motion signals.     

Effects of directional auditory and visual warnings at intersections on reaction times and speed reduction times

Intersection collision warning systems (ICWSs) have an important impact on driving safety because making the potential collision at intersection predictable, allow reducing the probability and severity of accidents. Among the several types of alarms to alert the driver of an imminent collision, those most used concerning the auditory and the visual stimulus. However, it is unclear whether is more effective an audio or a visual warning. In addition, no study compared the effects on drivers’ behavior induced by an acoustic and a visual directional warning. The main objective of the present study was to assess, in response to a potential conflict event at the intersections, the effects of directional auditory and visual warnings on driving performance.A driving simulator experiment was carried out to collect drivers’ behavior in response to a vehicle that failed to stop at the intersection. The parameters reaction time and speed reduction time were used for the evaluation of the effects on driving performance. These duration variables were modeled following the survival analysis, by the use of the accelerated failure time duration model with a Weibull distribution.Results showed that when the directional warning system (auditory or visual) was present, the drivers were able to detect earlier the violator vehicle. This effect led to a more comfortable braking maneuver and, thus, less possibilities of an unexpected maneuver for the following vehicle, avoiding the car – following collisions. The effectiveness of ICWSs was more evident for the directional auditory speech message; for this condition, in fact, the lower reaction time and the longer speed reduction time were obtained.The outcomes of the present study provide useful suggestions about the most effective collision warning systems that the automotive industry should develop and equip on vehicles.     

Spatial coding of auditory signals

Sequences of nine binary auditory signals (dots and dashes) were presented to 20 subjects in Experiment I. The subjects were instructed to internally organize the signals into two-dimensional arrays. Visual patterns (letters) could be recognized in these imaginary arrays in both upright and rotated orientations. In Experiment II, a group of nine subjects, which was instructed to use spatial imagery of this kind, reproduced significantly longer sequences of signals than nine control subjects. By means of internal spatial organization, experimental subjects were able to reproduce sequences up to 45 signals in length, whereas control subjects recalled near the chance level for portions of sequences longer than nine signals. Three levels of information processing were postulated to account for the results, with spatial organization occupying a mediating level between acoustic and verbal levels.     

Selective strategies in the assimilation of successively presented signals

It is found that performance in experiments on the psychological refractory period is highly affected by instructions. In the present experiment subjects were instructed either to handle the signals successively or to group them. Both instructions were obeyed. This seems to indicate that the human organism has various strategies available. Which strategy is actually applied is likely to depend on the structure of the experimental situation, and partly also, on momentary preference. This may explain the variety of results in the literature on this subject.

Finally, it is found that, when two signals are presented simultaneously, the total reaction time is considerably shorter if the signals are “grouped” than if they are “handled successively.” This difference disappears at interstimulus intervals of 0.2 sec. and 0.4 sec. The hypothesis is put forward, that the gain in time at the former case is due to simultaneous perceptual processing of the signals.     

Hemispheric lateralization of bilaterally presented homologous visual and auditory stimuli in normal adults, normal children, and children with central auditory dysfunction

Two experiments were conducted to examine the performance of normal adults, normal children, and children diagnosed with central auditory dysfunction presumed to involve the interhemispheric pathways on a dichotic digits test in common clinical use for the diagnosis of central auditory processing disorder (CAPD) and its corresponding visual analog. Results of the first experiment revealed a significant right ear advantage (REA) for the dichotic listening task and a left-visual-field advantage (LVFA) for the corresponding visual analog in normal adults and children. In the second experiment, results revealed a significantly larger REA in the children with CAPD as compared to the normal children. Results also revealed a reversed cerebral asymmetry (RVFA) for the children with CAPD on the visual task. Significant cross-modal correlations suggest that the two tasks may reflect, at least in part, similar interhemispheric processing mechanisms in children. Findings are discussed in relation to differential diagnosis and modality-specificity of CAPD.     

Immediate and delayed recognition of sequentially presented random shapes.

Two experiments tested whether short-term memory accounts for the recency effect observed with rapid sequential presentation of nonverbal stimuli. Four random shapes were presented sequentially (with no interstimulus interval) on each trial at rates of 150 msec, 250 msec, 500 msec, and 1,000 msec per stimulus. Subsequent recognition varied positively with exposure duration, ranging from 57% at 150 msec to 77% at 1,000 msec. Two serial position effects were observed: a slight decrease in recognition accuracy for the first stimulus in each sequence and a large increase in recognition for the last stimulus in each sequence. The recency effect was not altered by an intervening 30-sec delay, an intervening 30-sec copying task, or an intervening 30-sec copying and counting task. Since neither visual nor verbal distractors altered recognition accuracy, it was suggested that all shapes were processed directly into long-term memory storage. It also was hypothesized that long-term storage of a nonverbal stimulus requires identification of a distinctive feature of the stimulus and that this process may continue for a brief period after actual stimulus offset.     

Discontinuity in the enumeration of sequentially presented auditory and visual stimuli

The seeking of discontinuity in enumeration was recently renewed because Cowan [Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24, 87–185; Cowan, N. (2005). Working memory capacity. Hove: Psychology Press] suggested that it allows evaluating the limit of the focus of attention, currently estimated at four items. A strong argument in favour of a general constraint of the cognitive system is that similar discontinuities should be observed in modalities different from the classic simultaneous presentation of visual objects. Recently, data were provided on tactile stimuli, but the authors diverged in their conclusion about the existence of such discontinuity [Gallace, A., Tan, H. Z., & Spence, C. (2006). Numerosity judgments for tactile stimuli distributed over the body surface. Perception, 35(2), 247–266; Riggs, K. J., Ferrand, L., Lancelin, D., Fryziel, L., Dumur, G., & Simpson, A. (2006). Subitizing in tactile perception. Psychological Science, 17(4), 271–272]. Following a similar rationale, our study aimed at evaluating discontinuity in the enumeration of auditory and visual stimuli presented sequentially. The clear and similar discontinuity observed in error rates, response times and given responses for both modalities favours the general capacity limit view, but also questions the size of this capacity, because the discontinuity occurred here at size 2. However, the masking of stimuli in sensory memory could not be entirely discarded.     

Perception of signals presented in the periphery of the visual field

Two experiments were performed which tested the type of information that can be extracted from the periphery of the visual field, i.e. content information or position information. In both studies two digits were compared, one presented at the left and one at the right of the subject's meridian, seperated by a binocular visual angle, comprising either an eye-field (45°) or a head-field display (100°). In the first experiment the right signal was presented in separate blocks of either degraded or undegraded digits. In the case of undegraded digits, processing efficiency was better in the eye-field than in the head-field. With degraded digits this eye-field advantage was significantly smaller, but did not altogether disappear, suggesting that information about both the content and the position of digits in the periphery is acquired in the eye-field as opposed to the head-field. In the second experiment degraded and undegraded digits occured randomly within the same block of trials. This was done to investigate whether peripheral information is acquired automatically or through controlled processing. The results indicate a small eye-field advantage, about equal for both degraded and undegraded digits. This supports the controlled processing hypothesis, at least with regard to the acquisition of content information from the periphery.     

Mental rotation of laterally presented random shapes in males and females

Eighteen right-handed subjects (9 males, 9 female) were to decide if laterally presented random shapes were identical or a mirror image of a centrally presented standard shape. The lateral shapes were rotated over 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, or 300 degrees. For unrotated (0 degrees) mirror image stimuli, females showed a significant right visual-field advantage, whereas males showed no significant hemifield effect. The rate of rotation was equivalent for both sexes. Field of presentation did not affect the rotation rate either. The present results support a growing number of findings that indicate that the interpretation of mental rotation as a typical right-hemispheric spatial-processing task is questionable.     

Recall of rapidly presented random chess positions is a function of skill

A widely cited result asserts that experts’ superiority over novices in recalling meaningful material from their domain of expertise vanishes when they are confronted with random material. A review of recent chess experiments in which random positions served as control material (presentation time between 3 and 10 sec) shows, however, that strong players generally maintain some superiority over weak players even with random positions, although the relative difference between skill levels is much smaller than with game positions. The implications of this finding for expertise in chess are discussed and the question of the recall of random material in other domains is raised.     

Detection and recognition of auditory patterns

The detection/recognition theorem (Starr, Metz, Lusted, & Goodenough, 1975) provides a signal detection theory prediction of an observer's ability to identify one of a set of possible signals on the basis of the observer's ability to detect whether any signal is presented. The present findings show that the theorem can be applied to complex auditory stimuli in a fashion that is not merely a trivial extension of the results obtained with simple auditory stimuli.     

Processing interaction between two dimensions of nonphonetic auditory signals.

In 1974 Wood proposed a hybrid serial-parallel model to account for the within-stimulus interactions between the acoustic cue of "pitch" and the phonetic cure of "place." Three of the five experiments in this paper replicate the Wood findings with analogous, clearly nonphonetic stimuli and thus refute Wood's implicit assumption of the involvement of any uniquely phonetic processes as factors in his results. The experiments in this paper demonstrate that the patterns of interaction found by Wood are independent of the experience of the subjects, the order of cue presentation, and whether the cues are presented simultaneously or sequentially. We conclude that the given patterns of interaction are general characteristics of the auditory system. These characteristics probably are not related to backward or forward "recognition" masking but may be a function of several other general factors.