Peripheral Detection Task Research Articles

Mesopic visual efficiency I: detection threshold measurements

Achromatic thresholds are measured at three sites to investigate the effects of light spectrum on achromatic detection thresholds in the mesopic region. The results of measurements using quasi-monochromatic targets reveal spectral sensitivity functions with two or three peaks, a so-called `chromatic effect' which is assumed to be due to the influence of the colour-opponent channels. This chromatic contribution seem to be less significant at lower luminances but it is accentuated for peripheral observation. Results obtained with broadband stimuli show that the contrast threshold, defined in terms of V(λ), is markedly higher for red targets than for other colours, particularly at lower light levels. For these broadband targets, contrast threshold values calculated using the new spectral sensitivity curves instead of V(λ) are in better agreement with the experimental results, particularly for the peripheral detection task.

Driver experience and cognitive workload in different traffic environments

How do levels of cognitive workload differ between experienced and inexperienced drivers? In this study we explored cognitive workload and driver experience, using a secondary task method, the peripheral detection task (PDT) in a field study. The main results showed a large and statistically significant difference in cognitive workload levels between experienced and inexperienced drivers. Inexperienced, low mileage drivers had on average approximately 250 milliseconds (ms) longer reaction times to a peripheral stimulus, than the experienced drivers. It would, therefore, appear that drivers with better training and experience were able to automate the driving task more effectively than their less experienced counterparts in accordance with theoretical psychological models. It has been suggested that increased training and experience may provide attention resource savings that can benefit the driver in handling new or unexpected traffic situations.

Mobile phone use – effects of conversation on mental workload and driving speed in rural and urban environments

The study was concerned with the effects of mobile phone conversation on simulated driving in different traffic environments. Forty-eight participants drove a distance of 70 km on a route which led through different environments. The environments were: rural environment with a speed limit of 90 km/h, rural environment with a speed limit of 70 km/h, urban environment of low complexity, urban environment of medium complexity and urban environment of high complexity. The experimental design was mixed with phone mode (handsfree/handheld) as a between-subjects factor and phone use (yes/no) and traffic environment as within-subjects factors. Performance on a peripheral detection task (PDT) – a measure of mental workload – presented while driving, was impaired by mobile phone conversation in all environments. PDT performance was, however, remarkably poor at the complex urban environment, even when the participants were not using the phone. Driving speed was reduced by conversation in all environments for handheld mode, but only in two environments for handsfree mode – the rural environment with a speed limit of 90 km/h and the complex urban environment. The effects on speed could be interpreted as a compensatory effort for the increased mental workload.

The effects of conversation on attention and peripheral detection: Is talking with a passenger and talking on the cell phone different?

In this study conversation with a remote person (hands-free phone), an in-vehicle person (passenger), and a no conversation (baseline) condition were compared on measures of attention and peripheral detection. We held conversation pace constant so that any difference found in attention or peripheral detection could be attributed to the distinctive feature of the type of conversation (remote, in-vehicle). The difficulty level of the verbal task was included as a second independent variable. Forty-eight undergraduate students participated in all conditions of a within-subjects design. The results revealed that conversation resulted in slower reactions and fewer correct responses on both attention and Peripheral Detection tasks compared to no conversation, while conversation type (remote/in-person) did not make a significant difference. Difficulty of the verbal task affected performance on the Peripheral Detection task but not on the attention task. These findings imply that conversation has a negative effect on attention and peripheral detection which are important components of driving. This effect may be greater with difficult conversations.

Mobile phone use—Effects of handheld and handsfree phones on driving performance

The study was concerned with effects of handsfree and handheld mobile phone dialling and conversation in simulated driving. In the main experiment dealing with conversation, 48 participants drove a distance of about 70 km on a route which led through urban and rural environments. In the dialling experiment, the participants drove a distance of 15 km on a rural two-lane road. The experimental design was mixed with phone mode as a between-subjects factor and phone use (yes/no) as a within-subjects factor. Performance on a peripheral detection task (PDT) while driving was impaired by dialling and conversation for both phone modes, interpreted as an increase in mental workload. Driving performance was impaired by dialling—lateral position deviation increased in a similar way for both phone modes. Conversation had, however, opposite effects—lateral position deviation decreased in a similar way for both phone modes. Driving speed decreased as an effect of dialling with the greatest effect for handsfree phone mode. Conversation also caused reduced speed, but only for handheld phone mode. The effects on speed can be interpreted as a compensatory effort for the increased mental workload. In spite of the compensatory behaviour, mental workload was still markedly increased by phone use. Subjective effects of dialling and conversation were also analysed. Most participants reported a speed decrease but no effect on lateral position deviation as an effect of dialling or conversation. In the conversation experiment, driving performance was rated better for handsfree than for handheld mode. In the dialling experiment, no difference between the two phone modes appeared.

Peripheral detection as a workload measure in driving: Effects of traffic complexity and route guidance system use in a driving study

Recent studies have explored a promising method to measure driver workload—the Peripheral Detection Task (PDT). The PDT has been suggested as a standard method to assess safety-relevant workload from the use of in-vehicle information systems (IVIS) while driving. This paper reports the German part of a Swedish-German cooperative study in which the PDT was investigated focusing on its specific sensitivity compared with alternative workload measures. Forty-nine professional drivers performed the PDT while following route guidance system instructions on an inner-city route. The route consisted of both highly demanding and less demanding sections. Two route guidance systems that differed mainly in display size and display organization were compared. Subjective workload ratings (NASA-TLX) as well as physiological measures (heart rate and heart rate variability) were collected as reference data. The PDT showed sensitivity to route demands. Despite their differing displays, both route guidance systems affected PDT performance similarly in intervals of several minutes. However, the PDT proved sensitive to peaks in workload from IVIS use and from the driving task. Peaks in workload were studied by video analyses of four selected subsections on the route. Subjective workload ratings reflected overall route demands and also did not indicate differing effects of the two displays. The physiological measures were less sensitive to workload and indicated emotional strain as well. An assessment of the PDT as a method for the measurement of safety-related workload is given.

Using mobile telephones: cognitive workload and attention resource allocation

Driver distraction is recognized as being one of the central causes of road traffic incidents and mobile telephones are tangible devices (among many other electronic devices) that can distract the driver through changes in workload. Forty participants completed a motorway route characterized by a low level of road complexity in the form of vehicle handling and information processing. A peripheral detection task (PDT) was employed to gauge mental workload. We compared effects of conversation type (simple versus complex) and telephone mode (hands-free versus handheld) to baseline conditions. The participants’ reaction times increased significantly when conversing but no benefit of hands-free units over handheld units on rural roads/motorways were found. Thus, in regard to mobile telephones, the content of the conversation was far more important for driving and driver distraction than the type of telephone when driving on a motorway or similar type of road. The more difficult and complex the conversation, the greater the possible negative effect on driver distraction.

Peripheral detection as a measure of driver distraction. A study of memory-based versus system-based navigation in a built-up area

The effect of in-vehicle information systems (IVIS) on traffic safety is currently under debate and suitable methods for measuring and comparing the impact of such devices on driver behaviour are urgently required. The secondary-task technique may be a good tool for objective measurement of driver distraction caused by IVIS. The present study summarises previous results of secondary-task studies in traffic contexts and investigates the suitability of one secondary-task method, the peripheral detection task (PDT)-method, as a standard procedure for safety testing and evaluation of IVIS. The study was concerned with the effect of navigation messages on PDT-performance (reaction time and hit rate) taking into account also behavioural variables. Professional drivers served as subjects. They had extensive prior local-knowledge and experience of driving in the built-up area in which the experiment took place. They were required to drive two different routes, one after memory and the other in accordance with navigation messages a standard navigation system installed in the car. In the navigation system condition subjects were subdivided into three groups, receiving either verbal, visual or both visual and verbal (full) navigation messages. Driving behaviour was virtually uninfluenced by navigation condition (memory versus navigation system) and message modality (full, visual or verbal) whereas PDT-performance, showed some effects of navigation condition on subjects’ reaction times and hit rates. Pairwise comparison of message modality within each three groups showed a prolongation in reaction time and a marginally significant decrease in hit rate with full navigation messages (combined visual and verbal ones). Visual navigation messages affected only hit rate and no significant differences between navigation conditions were observed for the group presented with verbal messages. The pattern of results suggests that the PDT-method is biased toward visual sources of information from IVIS. As visual information processing is an important component in safe driving, the PDT-method is suitable as a predominant method in a test battery, but for unbiased measurement of distraction, methods less dependent on mode of presentation would be more appropriate.

Age Related Differences in Driving Performance and Target Identification

We investigated the effects of age and simulated driving scenario complexity (low, high) on measures of driving performance and on a peripheral letter detection and identification task. The right and left turn signals were used to indicate whether a letter was or was not part of a three letter target set, respectively. The participants were 12 younger (ages 18–41) and 12 older individuals (64–85). Complexity was manipulated by varying the number of stoplights that could potentially turn red as a participant approached an intersection and the number of obstacles (e.g. other traffic, intersections etc). The results showed that older subjects drove slower overall, had more difficulty controlling the simulator when navigating curves, had more accidents, and identified fewer target letters than the younger participants. As the complexity of the scenario increased the older participants showed a disproportionate increase in accidents and a marginally significantly (p <.06) greater decrease in peripheral letter identification than the younger drivers.

Stimulus size scaling and foveal load as determinants of peripheral target detection

This paper reports two experiments on the effect of scaling the size of stimuli (using factors derived from consideration of cortical magnification) on the detection of peripheral visual targets. In the first experiment two levels of magnification, fully M-scaled and half M-scaled, were used to scale stimuli that were presented briefly. The performance decrement normally associated with increasing retinal eccentricity did not occur with both levels of magnification. There was an unexpected decline in performance at low eccentricities and possible explanations are discussed. The second experiment investigated the effects of half M-scaling on a peripheral detection task with the addition of foveal cognitive loading as would be found in many practical tasks. Half M-scaling improved performance with and without the presence of foveal loading, and the improvement was greater for the foveal load condition when the target was at the larger eccentricities. These results provide a useful indication of the possibility of reducing the effect of tunnel vision for visual inspection tasks on visual displays or, possibly, control panels through the development of variable resolution projection displays matching the psychophysical properties of the human visual system.

Peripheral detection and central task complexity.

Subjects verbally tracked a central task that differed on a complexity dimension (subsets of two, four, or eight digits), while indicating their detection of small peripheral lights by pressing a hand–held switch. Teichner's stress theory would predict that the more complex the central task, the longer would be the reaction times to the peripheral lights, and that the differences would be most pronounced in the far periphery (the funneling effect). Hebb's arousal theory, applied to vigilance behavior, would predict the opposite effect, where increasing the complexity of the central task would heighten the subject's vigilance performance. The results supported an arousal interpretation, with faster reaction times to the peripheral lights as central task complexity increased.