Ellen Jongen

Investigating the influence of working memory capacity when driving behavior is combined with cognitive load: An LCT study of young novice drivers

Distracted driving has received increasing attention in the literature due to potential adverse safety outcomes. An often posed solution to alleviate distraction while driving is hands-free technology. Interference by distraction can occur however at the sensory input (e.g., visual) level, but also at the cognitive level where hands-free technology induces working memory (WM) load. Active maintenance of goal-directed behavior in the presence of distraction depends on WM capacity (i.e., Lavies Load theory) which implies that people with higher WM capacity are less susceptible to distractor interference. This study investigated the interaction between verbal WM load and WM capacity on driving performance to determine whether individuals with higher WM capacity were less affected by verbal WM load, leading to a smaller deterioration of driving performance. Driving performance of 46 young novice drivers (17-25 years-old) was measured with the lane change task (LCT). Participants drove without and with verbal WM load of increasing complexity (auditory-verbal response N-back task). Both visuospatial and verbal WM capacity were investigated. Dependent measures were mean deviation in the lane change path (MDEV), lane change initiation (LCI) and percentage of correct lane changes (PCL). Driving experience was included as a covariate. Performance on each dependent measure deteriorated with increasing verbal WM load. Meanwhile, higher WM capacity related to better LCT performance. Finally, for LCI and PCL, participants with higher verbal WM capacity were influenced less by verbal WM load. These findings entail that completely eliminating distraction is necessary to minimize crash risks among young novice drivers.

The developmental pattern of stimulus and response interference in a color-object Stroop task: an ERP study

BackgroundSeveral studies have shown that Stroop interference is stronger in children than in adults. However, in a standard Stroop paradigm, stimulus interference and response interference are confounded. The purpose of the present study was to determine whether interference at the stimulus level and the response level are subject to distinct maturational patterns across childhood. Three groups of children (6–7 year-olds, 8–9 year-olds, and 10–12 year-olds) and a group of adults performed a manual Color-Object Stroop designed to disentangle stimulus interference and response interference. This was accomplished by comparing three trial types. In congruent (C) trials there was no interference. In stimulus incongruent (SI) trials there was only stimulus interference. In response incongruent (RI) trials there was stimulus interference and response interference. Stimulus interference and response interference were measured by a comparison of SI with C, and RI with SI trials, respectively. Event-related potentials (ERPs) were measured to study the temporal dynamics of these processes of interference.ResultsThere was no behavioral evidence for stimulus interference in any of the groups, but in 6–7 year-old children ERPs in the SI condition in comparison with the C condition showed an occipital P1-reduction (80–140 ms) and a widely distributed amplitude enhancement of a negative component followed by an amplitude reduction of a positive component (400–560 ms). For response interference, all groups showed a comparable reaction time (RT) delay, but children made more errors than adults. ERPs in the RI condition in comparison with the SI condition showed an amplitude reduction of a positive component over lateral parietal (-occipital) sites in 10–12 year-olds and adults (300–540 ms), and a widely distributed amplitude enhancement of a positive component in all age groups (680–960 ms). The size of the enhancement correlated positively with the RT response interference effect.ConclusionAlthough processes of stimulus interference control as measured with the color-object Stroop task seem to reach mature levels relatively early in childhood (6–7 years), development of response interference control appears to continue into late adolescence as 10–12 year-olds were still more susceptible to errors of response interference than adults.

The relation between cognitive control and risky driving in young novice drivers

This study investigated if decreased cognitive control, reflected in response inhibition and working-memory performance, is an underlying mechanism of risky driving in young novice drivers. Thirty-eight participants aged 17 to 25 years old, with less than 1 year of driving experience, completed a simulated drive that included several risky driving measures. Measures of response inhibition and verbal working memory were negatively associated with the standard deviation of the lateral lane position. Response inhibition, but not working memory, was also negatively related with the detection of, reaction to, and crashes with road hazards. Unexpectedly, increased cognitive control did not always relate to decreased risky driving. Visuospatial working-memory performance related positively with yellow-light running and negatively with the minimal following distance inside the city center. The findings evidence the role of cognitive control in explaining risky driving in young novice drivers. This relationship, however, differed per cognitive function and per driving parameter. Implications for future research and traffic safety interventions are discussed.

A simulator study on the impact of traffic calming measures in urban areas on driving behavior and workload.

This study examined the impact of traffic calming measures (TCM) on major roads in rural and urban areas. More specifically we investigated the effect of gate constructions located at the entrance of the urban area and horizontal curves within the urban area on driving behavior and workload. Forty-six participants completed a 34km test-drive on a driving simulator with eight thoroughfare configurations, i.e., 2 (curves: present, absent)×2 (gates: present, absent)×2 (peripheral detection task (PDT): present, absent) in a within-subject design. PDT performance (mean response time (RT) and hit rate) indicated that drivers experienced the road outside the urban area as cognitively less demanding relative to the more complex road environment inside the urban area. Whereas curves induced a speed reduction that was sustained throughout the entire urban area, variability of acceleration/deceleration and lateral position were increased. In addition, PDT performance indicated higher workload when curves were present (versus absent). Gate constructions locally reduced speed (i.e., shortly before and after the entrance) and slightly increased variability of acceleration/deceleration and lateral position nearby the entrance. However, the effects on SDL-A/D and SDLP are too small to expect traffic safety problems. It can be concluded that both curves and gate constructions can improve traffic safety. Notwithstanding, the decision to implement these measures will depend on contextual factors such as whether the road serves a traffic-, rather than a residential function.

Dissociation, resting EEG, and subjective sleep experiences in undergraduates

In this study, we explored whether individual differences in dissociation are related to certain resting electroencephalographic (EEG) parameters. Baseline EEG with eyes open and closed was recorded in an undergraduate sample (N = 67). Cortical power in the α range was inversely related to dissociative symptoms as measured by the Dissociative Experiences Scale, while both δ and &thgr; power where positively related to dissociation. However, sleep experiences, as indexed with the Iowa Sleep Experiences Survey, were unrelated to resting EEG characteristics. We propose that suppression in the α band and raised levels of &thgr; activity, which are typical for high dissociators, might help to explain why dissociative symptoms are accompanied by attentional and memory deficits.

Cognitive processes and attitudes in bipolar disorder: A study into personality, dysfunctional attitudes and attention bias in patients with bipolar disorder and their relatives

BACKGROUND Research in cognitive processes and attitudes in bipolar disorder is scarce and has provided mixed findings, possibly due to differences in current mood state. It is unclear whether alterations in cognitive processes and attitudes are only related to the depressive mood states of bipolar patients or also represent a vulnerability marker for the development of future (depressive) episodes. This was investigated in the current study. METHODS Both implicit (attentional bias for emotional words) and explicit (dysfunctional attitudes and personality characteristics) measures of cognitive processes and attitudes were assessed in 77 bipolar patients with varying levels of depressive symptoms (depressed=17, euthymic n=60), their healthy first-degree relatives (n=39) and a healthy control group (n=61). Analyses of variance were used to investigate differences between groups. RESULTS Mildly depressed patients with bipolar disorder demonstrated an attentional bias away from positive emotional words and showed increased dysfunctional attitudes and higher levels of neuroticism. Euthymic patients were largely comparable to healthy controls and only differed from controls in higher levels of neuroticism. Relatives were similar to controls on all measures, although they significantly differed from bipolar patients in displaying less neuroticism and more extraversion. LIMITATIONS No firm conclusions regarding causality can be drawn from the associations that were found between cognitive processes and attitudes and the evolution of mood symptoms in bipolar disorder. CONCLUSION Alterations in cognitive processes and attitudes in bipolar patients appear to be mostly related to the expression of mood symptomatology rather than to the vulnerability for bipolar disorder.

Pain report and pain-related evoked potentials operantly conditioned

Objective: The purpose of the present study was to answer the question whether pain report can be increased and decreased by operant conditioning. We predicted that the conditioned pain effects would remain significant after correction for social desirability and fantasy proneness. Furthermore, we tried to show that the neurophysiologic basis of verbal pain report, defined by pain (event)-related potentials, was affected by the conditioning procedure. Specifically, it was expected that the central recording site N150-P260 pain (event)-related potentials peak-to-peak amplitude would show the largest effect. Methods: There were 4 groups: an up-conditioning group, a down-conditioning group, an at-random conditioning, and no-feedback control group. Healthy patients received 45 calibrated pain stimuli of equal physical intensity and were asked to rate the pain intensity they experienced. Up-conditioning was established by rewarding the subject if pain report increased compared with the previous trial. Down-conditioning of pain report was achieved by rewarding a decrease in the pain score. Results: Results of the subjective pain reports clearly indicated that both forms of conditioning succeeded. Up-conditioning resulted in the highest pain scores and down-conditioning in the lowest scores with the two control groups in between them. Controlling for level of social desirability and fantasy proneness did not negatively influence these results. The N150-P260 pain (event)-related potentials peak-to-peak central recording site component also showed the predicted effect and reached statistical significance. Discussion: We concluded that the subjective report of pain as well as a specific pain-related potentials component can be operantly conditioned.

Inhibitory Control and Reward Predict Risky Driving in Young Novice Drivers – A Simulator Study

The purpose of this study is to unravel the cognitive mechanisms that underlie risky driving in young novice drivers. Based on the two pillars of the Dual Systems Model of adolescent risk taking, the authors hypothesized that (1) lower capacity for cognitive control (inhibitory control), (2) a rewarding context, and (3) the interaction of these predict risky driving and constitute part of the cognitive basis for the large number of crashes in the young novice driver population. Two groups different in age (n=31, 17-18 year-olds; n=22, 22-24 year-olds), but equal in driving experience participated in the experiment. Each participant completed two 28km test-drives in a STISIM M400 driving simulator. In the first drive, participants were asked to drive as they normally do. For the second drive, participants were told they could obtain a monetary reward for completing the drive as fast as possible, although for each collision or traffic violation (except speeding), penalty time would be imposed. Inhibitory control was measured by means of a stop signal reaction time task (SSRT). Measures of risky driving included: standard deviation of lateral lane position (SDLP), responses to critical events, speeding, and red light running. The authors found that: (1) inhibitory control still improves within the young driver population; (2) lowered inhibitory control had a driving specific effect: drivers with lower inhibitory control (SSRT) had a higher SDLP; (3) a rewarding context predicts risky driving as speeding and red light running occurred more often in the trip with than without reward.

Effects of concurrent working memory load on distractor and conflict processing in a name-face Stroop task

To examine the time course of effects of working memory (WM) load on interference control, ERPs were measured in a combined WM and Stroop task. A WM load of 0, 2, or 4 letters was imposed, and during the maintenance-interval Stroop trials were presented that required participants to classify names of famous people while ignoring faces that were either congruent or incongruent with the names. Behavioral interference was not modulated by WM load, but WM load led to an overall reduction of Stroop stimulus encoding as reflected by reduced N170 and N250 amplitudes independent of congruency. Incongruent distractor faces induced interference as shown by a delayed and reduced positivity between 480-600 ms (N450) and an enhanced positivity between 760-1000 ms (P600), indicating longer stimulus evaluation, conflict detection, and conflict resolution, respectively. WM load led to an increase of the P600 at frontal and parietal sites, possibly reflecting PFC-driven top-down control of posterior sites, necessary for conflict resolution.

70 km/h speed limits on former 90 km/h roads: effects of sign repetition and distraction on speed

Objective: It was investigated how speed limit repetition and distraction affect drivers’ speed management throughout a road section where the imposed speed limit is not in accordance (too low) with road design. Background: It is not clear how driving speed evolves and to what degree speed limit repetition is necessary on roads where the imposed speed limit is not in accordance (too low) with road design. It is furthermore of interest how all these factors are influenced by driver distraction. Method: In a driving simulator, 47 volunteers completed one trip with and without distraction. Within each trip, three configurations were presented: speed limit sign repetition after every intersection, repetition only in the middle of a segment, or no repetition. Results: Distraction lowered driving speed. Speed management varied depending on speed limit repetition. The speed limit was exceeded more often when speed limit signs were repeated less frequently. When drivers were not reminded of the limit, speed linearly increased throughout the segment. In all three configurations, speed increased toward the end of the segment, but this increase was largest when there had been no repetition at all of the speed limit. Conclusion: In low-demanding road designs that allow drivers to exceed the speed limit, limit repetition is necessary. Frequent repetition may be preferred, as speed management was most homogenous in that case. Application: The proposed analysis of speed management throughout a section increases our understanding of how speed evolves and thereby shows where repetition of the speed limit is necessary.