Ensar Becic

Training effects on dual-task performance: Are there age-related differences in plasticity of attentional control?

A number of studies have suggested that attentional control skills required to perform 2 tasks concurrently become impaired with age (A. A. Hartley, 1992; J. M. McDowd & R. J. Shaw, 2000). A. A. Hartley (2001) recently observed that the age-related differences in dual-task performance were larger when the 2 tasks required similar motor responses. The present study examined the extent to which age-related deficits in dual-task performance or time sharing--in particular, dual-task performance of 2 discrimination tasks with similar motor requirements--can be moderated by training. The results indicate that, even when the 2 tasks required similar motor responses, both older and younger adults could learn to perform the tasks faster and more accurately. Moreover, the improvement in performance generalized to new task combinations involving new stimuli. Therefore, it appears that training can substantially improve dual-task processing skills in older adults.

Influence of age and proximity warning devices on collision avoidance in simulated driving

Objective: We conducted a set of experiments to examine the utility of several different uni- and multimodal collision avoidance systems (CASs) on driving performance of young and older adult drivers in a high-fidelity simulator. Background: Although previous research has examined the efficacy of different CASs on collision avoidance, there has been a dearth of studies that have examined such devices in different driving situations with different populations of drivers. Method: Several different CAS warnings were examined in varying traffic and collision configurations both without (Experiment 1a) and with (Experiment 2) a distracting in-vehicle task. Results: Overall, collision avoidance performance for both potential forward and side object collisions was best for an auditory/visual CAS, which alerted drivers using both modalities. Interestingly, older drivers (60—82 years of age) benefited as much as younger drivers from the CAS, and sometimes they benefited more. Conclusion: These data suggest that CASs can be beneficial across a number of different driving scenarios, types of collisions, and driver populations. Application: These results have important implications for the design and implementation of CASs for different driver populations and driving conditions.

Driving impairs talking

It is well known that conversation (e.g, on a cell phone) impairs driving. We demonstrate that the reverse is also true: Language production and comprehension, and the encoding of the products of comprehension into memory, are less accurate when one is driving. Ninety-six pairs of drivers and conversation partners engaged in a story-retelling task in a driving simulator. Half of the pairs were older adults. Each pair completed one dual-task block (driving during the retelling task) and two single-task control blocks. The results showed a decline in the accuracy of the drivers’ storytelling and of their memory for stories that were told to them by their nondriving partners. Speech production suffered an additional cost when the difficulty of driving increased. Measures of driving performance suggested that the drivers gave priority to the driving task when they were conversing. As a result, their linguistic performance suffered.

Detecting Transient Changes in Dynamic Displays: The More You Look, the Less You See

Objective: Two experiments examined the detectability of transient changes in cluttered and dynamic displays and optimal scan strategies for performance. Background: Research has demonstrated that onset changes are prioritized by the attention system and onsets are often used to signal important display changes. However, research has mostly used uncluttered, static displays and has largely ignored the role of scan strategy. Method: W e had participants monitor a cluttered and dynamic display and respond when an object changed color or onset abruptly. Scan strategies were also evaluated. In another experiment participants were instructed to use particular strategies to detect changes. Results: Consistent with previous results, onset events were detected better than were color change events. Scan strategy accounted for a large proportion of variance in detection performance. Participants who made few eye movements performed best. Participants who actively scanned the display performed worst. When poor performers were instructed to make few eye movements, their performance matched that of the best performers. Conclusion: Onset alerts can be an effective means of signaling important events in complex displays. Additionally, scan strategy plays an important role in the detection of transient events. Application: These results have important implications for training operators to search for transient changes within dynamic and cluttered displays.

Training older adults to search more effectively: scanning strategy and visual search in dynamic displays.

The authors examined the ability of older adults to modify their search strategies to detect changes in dynamic displays. Older adults who made few eye movements during search (i.e., covert searchers) were faster and more accurate compared with individuals who made many eye movements (i.e., overt searchers). When overt searchers were instructed to adopt a covert search strategy, target detection performance increased to the level of natural covert searchers. Similarly, covert searchers instructed to search overtly exhibited a decrease in target detection performance. These data suggest that with instructions and minimal practice, older adults can ameliorate the cost of a poor search strategy.

Age-related differences in visual search in dynamic displays.

The authors examined the ability of younger and older adults to detect changes in dynamic displays. Older and younger adults viewed displays containing numerous moving objects and were asked to respond when a new object was added to the display. Accuracy, response times, and eye movements were recorded. For both younger and older participants, the number of eye movements accounted for a large proportion of variance in transient detection performance. Participants who actively searched for the change performed significantly worse than did participants who employed a passive or covert scan strategy, indicating that passive scanning may be a beneficial strategy in certain dynamic environments. The cost of an active scan strategy was especially high for older participants in terms of both accuracy and response times. However, older adults who employed a passive or covert scan strategy showed greater improvement, relative to older active searchers, than did younger adults. These results highlight the importance of individual differences in scanning strategy in real-world dynamic, cluttered environments.

Temporal Limitations in Multiple Target Detection in a Dynamic Monitoring Task

Objective: Two experiments examined the detectability of multiple transient changes within a cluttered and dynamic display (a simulated sonar display). Background: Research suggests that there are severe limitations when multiple targets must be detected within close temporal proximity. The present research explored whether these limitations influence performance in a dynamic monitoring task. Method: Participants monitored a cluttered and dynamic display and reported the number of new objects that appeared (one to four objects). The time between onset events was varied. A blinking cue sometimes accompanied each new object, giving observers multiple opportunities to detect it. Results: A large decrease in performance was observed when participants were asked to detect multiple targets within a short period of time. Performance was worse than predicted based on the attention literature. Performance suffered when observers were asked to detect more than two or three targets. The blinking cue greatly attenuated this performance deficit, even for short-duration blinking cues (one blink). Conclusion: Operators can easily become overwhelmed when asked to respond to even a small number of events when these events occur close in time. Extending transient events in time improves performance, but some attentional limitations may be difficult or impossible to overcome. Application: These results have important implications for systems in which important events may occur within close temporal proximity (e.g., when a sonar operator is tasked with detecting threats in the battle space). Situations in which these limitations may or may not influence performance are discussed.

Examination of the Efficacy of Proximity Warning Devices for Young and Older Drivers

OBJECTIVES The study was conducted to examine the efficacy of uniand multi-modal proximity warning devices for forward object collision and side-object detection for young and older adult drivers. METHODS Two experiments were conducted, each with 20 young (18 to 30 years of age) and 20 older (61 to 80 years of age) healthy and high functioning drivers. In each, participants drove a series of brief (~ 4 minute) highway scenarios with temporally unpredictable forward and side collision events (i.e., other vehicles). The experiments were conducted in a fixed-base Drive Safety simulator with a 135-degree wrap-around forward field and a 135-degree rear field. Light crosswinds were included in Experiment 1, while heavier crosswinds were introduced in the second experiment. A secondary visual read-out task from an in-vehicle LCD display was also included in the second experiment. In Experiment 1, potential collision events were signaled 2.2 seconds before impact by visual, auditory, auditory+visual or tactile+visual warnings that were spatially mapped to the location of the obstacle (left, right or center). A control condition in which subjects drove without any proximity warning device was also included in the experiment. Experiment 2 included the control, auditory+visual and visual warnings from Experiment 1. A number of dependent measures were collected, including velocity, lane position, steering wheel movement, brake and accelerator position. However, we will focus on the response time (as measured by steering wheel deflections or removal of the foot from the accelerator) to potential collision events as well as the number of collisions in different experimental conditions. RESULTS In both Experiments 1 and 2, the auditory+visual warning device produced the most rapid response and also resulted in the fewest collisions. The reduction in response time and collisions, relative to the no-warning control condition was larger in Experiment 2 than in Experiment 1, PROCEEDINGS of the Third International Driving Symposium on Human Factors in Driver Assessment, Training and Vehicle Design 294 likely as a result to the more challenging driving scenarios (with the higher and unpredictable winds and introduction of the secondary task) in this experiment. Older adults responded just as quickly as younger adults to the potential collision events in both of the experiments. This is a very surprising finding given a voluminous laboratory literature, which suggests that older adults display slower responses than younger adults on almost any task that has been examined in the laboratory. In an effort to understand the age-equivalent response times to collision events, we asked young and older participants from the first experiment to take part in an additional experimental session in which they made simple and choice responses to visual and auditory events in a sound attenuated subject booth. Older adults were substantially (~ 35%) slower in each of these simple and choice tasks performed in the laboratory. Older adults displayed the same performance benefits (in terms of speeded response time and reductions in collisions) from the proximity warning devices, and particularly the auditory+visual device, in both of the experiments as younger adults. However, in Experiment 2, older adults displayed these benefits by neglecting the number read-out secondary task. CONCLUSIONS There are several important conclusions from the present study. First, proximity warning devices, and particularly auditory+visual devices, can substantially speed response time and reduce potential collisions in simulated driving. This is an important observation that has the potential to reduce automobile accidents. Second, both younger and older adults benefit from the proximity warning devices. Such a finding suggests, that at least for individuals with normal vision and hearing, these devices might have substantial utility across a wide variety of drivers. Third, quite to our surprise, older adult drivers responded just as quickly, with and without the proximity warning devices, to potential collision events as younger drivers. Interestingly, ageequivalence in response time to potential collisions was not observed in simple and choice auditory and visual laboratory response time tasks. Such data tentatively suggests that experience and expertise in driving may act as a moderator of age-related decline in general slowing. Given the unpredictable nature of the potential collision events in our study, older drivers may be capitalizing on high levels of vigilance and attentional focus on driving relevant tasks to maintain their ability to rapidly respond to collision events. This hypothesis is supported, in part, by the decrements in secondary task performed observed for the older but not for the younger adults in Experiment 2. The results from the present study are encouraging both with respect to the utility of proximity warning devices as a means to enhance driver safety as well as for their potential application to drivers of different ages and experience levels. However, clearly additional research will be needed to verify these results in more challenging simulator and on the road driving situations.

Age-Related Differences in the Use of Background Layout in Visual Search

ABSTRACT The effect of background layout on visual search performance, and more specifically on the tendency to refixate previously inspected locations and objects, was investigated. Older and younger adults performed a search task in which a background layout or landmark was present or absent in a gaze contingent visual search paradigm. Regardless of age, participants demonstrated fewer refixations when landmarks were present, with older adults showing a larger landmark advantage. This visual search advantage did not come at the cost of saccadic latency. Furthermore, the visual search performance advantage obtained in the presence of a background layout or landmark was observed both for individuals with small and large memory spans.