Impaired Driving Performance as Evidence of a Magnocellular Deficit in Dyslexia and Visual Stress.

High comorbidity and an overlap in symptomology have been demonstrated between dyslexia and visual stress. Several researchers have hypothesized an underlying or causal influence that may account for this relationship. The magnocellular theory of dyslexia proposes that a deficit in visuo-temporal processing can explain symptomology for both disorders. If the magnocellular theory holds true, individuals who experience symptomology for these disorders should show impairment on a visuo-temporal task, such as driving. Eighteen male participants formed the sample for this study. Self-report measures assessed dyslexia and visual stress symptomology as well as participant IQ. Participants completed a drive simulation in which errors in response to road signs were measured. Bivariate correlations revealed significant associations between scores on measures of dyslexia and visual stress. Results also demonstrated that self-reported symptomology predicts magnocellular impairment as measured by performance on a driving task. Results from this study suggest that a magnocellular deficit offers a likely explanation for individuals who report high symptomology across both conditions. While conclusions about the impact of these disorders on driving performance should not be derived from this research alone, this study provides a platform for the development of future research, utilizing a clinical population and on-road driving assessment techniques.

Does a sensory processing deficit explain counting accuracy on rapid visual sequencing tasks in adults with and without dyslexia?

The experiments conducted aimed to investigate whether reduced accuracy when counting stimuli presented in rapid temporal sequence in adults with dyslexia could be explained by a sensory processing deficit, a general slowing in processing speed or difficulties shifting attention between stimuli. To achieve these aims, the influence of the inter-stimulus interval (ISI), stimulus duration, and sequence length were evaluated in two experiments. In the first that used skilled readers only, significantly more errors were found with presentation of long sequences when the ISI or stimulus durations were short. Experiment 2 used a wider range of ISIs and stimulus durations. Compared to skilled readers, a group with dyslexia had reduced accuracy on two-stimulus sequences when the ISI was short, but not when the ISI was long. Although reduced accuracy was found on all short and long sequences by the group with dyslexia, when performance on two-stimulus sequences was used as an index of sensory processing efficiency and controlled, group differences were found with presentation of stimuli of short duration only. We concluded that continuous, repetitive stimulation to the same visual area can produce a capacity limitation on rapid counting tasks in all readers when the ISIs or stimulus durations are short. While reduced accuracy on rapid sequential counting tasks can be explained by a sensory processing deficit when the stimulus duration is long, slower processing speed in the group with dyslexia explains the greater inaccuracy found as sequence length is increased when the stimulus duration is short.

The effect of distraction on the Word Memory Test and Test of Memory Malingering performance in patients with a severe brain injury.

This research compares the performance of a sample of non-litigating participants with severe brain injury on both the WMT and TOMM under conditions of (1) full effort, (2) distraction, or (3) simulated malingering. The study included 60 participants with a severe brain injury and used restricted randomization to assign participants to the groups. Following Craik (1982) an auditory distraction task was used during the learning phase of each test in the distraction group, while a scenario adapted from Tombaugh (1997) was used to encourage simulation of memory impairment in the simulated malingering group. The results of this study clearly showed that while both tests demonstrated excellent sensitivity, the false positive rates for the WMT were significantly greater than those for the TOMM. It was concluded that the so-called "effort" components of the WMT required more cognitive capacity than was previously believed.

Post-Traumatic Stress Disorder, Depression and Anxiety among North Korean Refugees: A Meta-Analysis.

OBJECTIVE: Post-traumatic stress disorder is common among North Korean refugees who have fled their country for economic, financial and humanitarian reasons. Co-morbid depression and anxiety are also common among North Korean refugees, due to the difficulties they have faced within their country and during their escape journey. Depression and anxiety complicate treatment for post-traumatic stress disorder, and lead to poorer outcomes. Thus, the aim of the present study was to provide a meta-analysis of studies investigating post-traumatic stress disorder, depression, and anxiety among North Korean refugees. METHODS: Selected articles were published in English, and included measures of post-traumatic stress, and/or depression and anxiety. 10 studies were included in the depression meta-analysis, and 6 in the anxiety meta-analysis. RESULTS: A random-effects model revealed strong, significant associations between post-traumatic stress and depression, r=0.63, 95% CI (0.51, 0.72), p<0.001, z=8.33, and anxiety, r=0.51, 95% CI (0.36, 0.63), p<0.001, z=6.07. The relationships between post-traumatic stress, depression and anxiety were higher among adults and those with more than five years outside of North Korea. CONCLUSION: Depression appears to be an important treatment focus for North Korean refugees with post-traumatic stress.

The effects of anti-speeding advertisements on the simulated driving behaviour of young drivers.

Recent examinations of road safety communications, including anti-speeding advertisements, have considered the differential effects of positive and negative emotional appeals on driver behaviour. However, empirical evaluations of anti-speeding messages have largely relied on measures of viewers' reported intentions to comply with speed limits and the self-reported driving behaviour of viewers post-exposure, which might not be indicative of the direct effects that these messages have on real-world driving behaviour. The current research constitutes a first empirical evaluation of different real-world anti-speeding advertisements, as measured by their effects on young drivers' speeding behaviour, using a driving simulator. Licensed drivers (N=116) aged 17-25 years completed driving measures prior to, immediately following, and 7-10days after viewing one of four social marketing advertisements. Results indicated that young drivers' average driving speeds were modestly reduced immediately after they viewed an anti-speeding advertisement that depicted social consequences for speeding and employed a positive emotional appeal when compared to an emotion-matched control advertisement; however, this effect was not found for the anti-speeding advertisement depicting a crash. Interestingly, the results based on reported intentions to reduce speeding predicted the opposite pattern of results. However, there was no evidence that the immediate changes to speeding were maintained 7-10days later, and prompts during Phase 2 did not appear to have an effect. The implications of these findings for road safety advertisements targeting young drivers are discussed.

Cognitive Tests and Determining Fitness to Drive in Dementia: A Systematic Review.

Evidence has shown that although all individuals with dementia will eventually need to stop driving, most can continue to drive safely early in the disease. Fitness to drive needs to be monitored, and the use of cognitive testing to determine driver safety has been suggested. This review is the first to examine cognitive test results pertaining only to individuals with dementia. The aim was to examine the relationship between cognitive tests and driving to determine whether a cognitive assessment can be implemented as a tool to examine driver safety. A systematic review of 28 studies investigating the relationship between cognitive functioning and driving in individuals with dementia was conducted. The results of this review demonstrated a lack of consistency in the findings, with some studies showing a relationship between cognitive testing and driving performance for individuals with dementia, whereas others did not. Results relating to individual cognitive tests and measures confined to a single cognitive domain were variable and not consistently associated with driving performance. Studies consistently found that composite batteries predicted driving performance. The findings from this review support the use of composite batteries comprising multiple individual tests from different cognitive domains in predicting driving performance for individuals with dementia. Scores on individual tests or tests of a single cognitive domain did not predict driver safety. The composite batteries that researchers have examined are not clinically usable because they lack the ability to discriminate sufficiently between safe and unsafe drivers. Researchers need to develop a reliable, valid composite battery that can correctly determine driver safety in individuals with dementia.

Differential effects of traffic sign stimuli upon speeding in school zones following a traffic light interruption.

Motorists whose journey has been interrupted by signalized traffic intersections in school zones resume their journey at a faster vehicle speed than motorists who have not been required to stop. Introducing a flashing "check speed" sign 70m after the traffic intersections counteracts this interruptive effect. The present study examined which aspects of a reminder sign are responsible for reducing the speeding behavior of interrupted motorists. When a sign that combines both written text and flashing lights was introduced, interrupted motorists did not speed, traveling on average 0.82km/h below the 40km/h speed limit when measured 100m from traffic intersections. Alternatively, when only the flashing lights were visible the interrupted motorists sped 3.36km/h over the 40km/h speed limit. Similar vehicular speeds were observed when only the written text was visible and when no sign was present (7.67 and 7.49km/h over the 40km/h speed limit, respectively). This indicates that static reminder signs add little value over the absence of a school zone reminder sign; the presence of both cues is necessary to fully offset the interruptive effect. This study also highlights the benefit of using exogenous visual cues in traffic signs to capture drivers' attention. These findings have practical implications for the design and use of traffic signs to increase compliance with posted speed limits.

A 'snapshot' of the visual search behaviours of medical sonographers.

Introduction: Visual search is a task that humans perform in everyday life. Whether it involves looking for a pen on a desk or a mass in a mammogram, the cognitive and perceptual processes that underpin these tasks are identical. Radiologists are experts in visual search of medical images and studies on their visual search behaviours have revealed some interesting findings with regard to diagnostic errors. In Australia, within the modality of ultrasound, sonographers perform the diagnostic scan, select images and present to the radiologist for reporting. Therefore the visual task and potential for errors is similar to a radiologist. Our aim was to explore and understand the detection, localisation and eye-gaze behaviours of a group of qualified sonographers. Method: We measured clinical performance and analysed diagnostic errors by presenting fifty sonographic breast images that varied on cancer present and degree of difficulty to a group of sonographers in their clinical workplace. For a sub-set of sonographers we obtained eye-tracking metrics such as time-to-first fixation, total visit duration and cumulative dwell time heat maps. Results: The results indicate that the sonographers' clinical performance was high and the eye-tracking metrics showed diagnostic error types similar to those found in studies on radiologist visual search. Conclusion: This study informs us about sonographer visual search patterns and highlights possible ways to improve diagnostic performance via targeted education.

A comparison of the degree of effort involved in the TOMM and the ACS Word Choice Test using a dual-task paradigm.

The aims of the current study were to: (a) examine the predictive validity and efficacy of the Advanced Clinical Solutions Word Choice Test (WCT) as a measure of effort relative to the Test of Memory Malingering (TOMM); (b) investigate whether performing a dual (distraction) task would undermine performance on either test; (c) assess the effect of coaching on the diagnostic accuracy of both the WCT and the TOMM; and (d) establish an optimal cut score for the WCT. The current study used a simulation design based on an analogue design in which normal participants were instructed to either apply full effort or simulate a brain injury on the tasks without being detected. Participants included 93 undergraduate university students who were randomly assigned to 1 of 4 conditions: (a) distraction, (b) uncoached traumatic brain injury (TBI) simulators, (c) coached TBI simulators, or (d) full effort. The results demonstrated that the WCT and the TOMM were effective in detecting simulated cognitive impairment. Both tests were resistant to the effects of distraction and were equally effective in detecting coached and uncoached simulators. A cut score of 42 on the WCT was found to provide optimal specificity and sensitivity on the test.

Speeding in school zones: violation or lapse in prospective memory?

Inappropriate speed is a causal factor in around one third of fatal accidents (OECD/ECMT, 2006). But are drivers always consciously responsible for their speeding behavior? Two studies are reported which show that an interruption to a journey, caused by stopping at a red traffic light, can result in failure to resume the speed of travel prior to the interruption (Study 1). In Study 2 we showed that the addition of a reminder cue could offset this interruption. These studies were conducted in a number of Australian school zone sites subject to a 40 km/h speed limit, requiring a reduction of between 20 km/h and 40 km/h. Motorists who had stopped at a red traffic signal sped on average, 8.27 km/h over the speed limit compared with only 1.76 km/h over the limit for those who had not been required to stop. In the second study a flashing "check speed" reminder cue, placed 70 m after the traffic lights, in the same school zones as those in Study 1 eliminated the interruptive effect of stopping with drivers resuming their journey at the legal speed. These findings have practical implications for the design of road environments, enforcement of speed limits, and the safety of pedestrians.

The effect of temporal and spatial frequency on phantom-contour detection.

Phantom contours are a visual illusion that can define regions with distinctive boundaries when no real surrounding edges exist. Spatial-frequency sensitivity is known to vary reliably across the visual-processing pathways, as does temporal-frequency sensitivity. Given that the effect of temporal frequency on phantom-contour detection has been previously established, and that the relationship between spatial frequency and temporal frequency is known, two experiments were designed to measure the highest level of spatial frequency that would still allow reliable pattern detection at different temporal frequencies by using the phantom-contour paradigm. The results revealed that phantom-contour detection is impaired when the stimulus has a high spatial-frequency content and that phantom-contour perception is supported by low spatial frequencies.