Risk compensation theory and bicycle helmets – Results from an experiment of cycling speed and short-term effects of habituation

It has been suggested that the safety benefits of bicycle helmets are limited by risk compensation. The current study contributes to explaining whether the potential safety effects of bicycle helmets are reduced by cyclists’ tendency to cycle faster when wearing them (as a result of risk compensation), and if this potential reduction can be associated with a change in perceived risk. A previous study (Fyhri & Phillips, 2013) showed that non-routine helmet users did not increase their speed immediately after being given a helmet to wear, while routine helmet users cycled more slowly. The current study tests whether the previously found reduction in speed in response to helmet removal – as an indirect indicator of risk compensation – could be established in non-routine helmet users, after a period of habituation while cycling with a helmet.We did this by conducting a randomized crossover trial, in which we used GPS-derived speed calculations and self-reported risk perception. To test the effect of habituation, we used a design where each participant took part in two rounds with a break between and each round having two trips. We collected the data in June 2015. Non-routine helmet users (N = 31) were recruited in the field (along cycle routes in Oslo), and through a sample drawn from the Falck National register of bicycle owners. In the first phase of the study, all participants were asked to complete a test route (2.4 km downhill) with and without a helmet. In the second phase of the experiment, conducted after 1.5–2 h, the same participants again completed the test route with and without a helmet. In the time between the first and second phases of the experiment, all participants were given helmets, and told to use them on a predefined bicycle route.Habituation to the helmet between the first and second phases of the experiment did not produce any decrease (with helmet removal) in speed, on top of the habituation that occurred while cycling down the hill (the order effect). Mean speed difference for cycling with/without a helmet before the break was −0.76 km/h, after the break this difference was 0.32 km/h; 95% CIs [−0.5, 2.9] and [−0.9, 1.5]. We argue that risk compensation is an unlikely effect of using a bicycle helmet, and probably cannot explain any adverse effects related to helmet legislation.     

Gestalt grouping effects on tactile information processing: when touching hands override spatial proximity

Using a tactile variant of the negative-priming paradigm, we analyzed the influence of Gestalt grouping on the ability of participants to ignore distracting tactile information. The distance between participants’ hands, to which the target and distractor stimuli were simultaneously delivered, was varied (near/touching hands vs. hands far apart). In addition, the influence of touching hands was controlled, as participants wore gloves and their hands were blocked from vision by a cover. The magnitude of the tactile negative-priming effect was modulated by the interaction between hand separation and whether or not gloves were worn. When the hands were touching, negative priming emerged only while wearing gloves that prevented direct skin-to-skin contact. In contrast, when the separation between the participants’ hands was larger, negative priming emerged only when gloves were not worn. This pattern of results is interpreted in terms of the competing influences of two interacting Gestalt principles—namely, connectedness and proximity—on the processing of tactile distractors.     

A comparison of visual and nonvisual sensory inputs to walked distance in a blind-walking task

Two experiments were conducted in order to assess the contribution of locomotor information to estimates of egocentric distance in a walking task. In the first experiment, participants were either shown, or led blind to, a target located at a distance ranging from 4 to 10 m and were then asked to indicate the distance to the target by walking to the location previously occupied by the target. Participants in both the visual and locomotor conditions were very accurate in this task and there was no significant difference between conditions. In the second experiment, a cue-conflict paradigm was used in which, without the knowledge of the participants, the visual and locomotor targets (the targets they were asked to walk to) were at two different distances. Most participants did not notice the conflict, but despite this their responses showed evidence that they had averaged the visual and locomotor inputs to arrive at a walked estimate of distance. Together, these experiments demonstrate that, although they showed poor awareness of their position in space without vision, in some conditions participants were able to use such nonvisual information to arrive at distance estimates as accurate as those given by vision.     

Target distance and adaptation in distance perception in the constancy of visual direction

Hay and Sawyer recently demonstrated that the constancy of visual direction (CVD) also operates for near targets. A luminous spot in the dark, 40 cm from the eyes, was perceived as stationary when S nodded his head. This implies that CVD takes target distance, as well as head rotation, into account as a stationary environment is perceived during head movements. Distance is a variable in CVD because, during a turning or nodding of the head, the eyes become displaced relative to the main target direction, the line between the target and the rotation axis of the head. This displacement of the eyes during head rotation causes an additional change in the target direction, i.e., a total angular change greater than the angle of the head rotation. The extent of this additional angular displacement is greater the nearer the target. We demonstrated that the natural combination of accommodation and convergence can supply the information needed by the nervous system to compensate for this additional target displacement. We also found that wearing glasses that alter the relation between these oculomotor adjustments and target distance produces an adaptation in CVD. An adaptation period of 1.5 h produced a large adaptation effect. This effect was not entirely accounted for by an adaptation in distance perception. Measurements of the alteration between oculomotor cues and registered distance with two kinds of tests for distance perception yielded effects significantly smaller than the effect measured with the CVD test. We concluded that the wearing of the glasses had also produced an adaptation within CVD.     

Action-specific effects underwater

Action-specific effects on perception are apparent in terrestrial environments. For example, targets that require more effort to walk, jump, or throw to look farther away than when the targets require less effort. Here, we examined whether action-specific effects would generalize to an underwater environment. Instead, perception might be geometrically precise, rather than action-specific, in an environment that is novel from an evolutionary perspective. We manipulated ease to swim by giving participants swimming flippers or taking them away. Those who estimated distance while wearing the flippers judged underwater targets to be closer than did participants who had taken them off. In addition, participants with better swimming ability judged the targets to be closer than did those with worse swimming ability. These results suggest perceived distance underwater is a function of the perceiver's ability to swim to the targets.     

The locus of semantic priming in RSVP target search

At what stage does semantic priming affect accuracy in target search? In two experiments, participants viewed two streams of stimuli, each including a target word among distractors. Stimulus onset asynchronies (SOAs) between the targets (T1 and T2) ranged from 53 to 213 msec. A word semantically related to one or neither of the targets preceded each trial. In Experiment 1, participants were instructed to report both targets. Although more primed than unprimed targets were reported, there was no cost for unprimed words. A strong interaction between SOA and T1 versus T2 was found, but priming did not interact with either variable. In Experiment 2, only related targets were reported. Performance was similar to that for primed targets in Experiment 1. Semantic priming does not seem to modulate how attentional resources are initially allocated between targets, but instead affects a later stage of processing, the point at which a target word reaches lexical identification.     

听障和听力正常人群空间主导性和空间参照框架的交互作用

通过要求被试分别在近处空间和远处空间完成空间参照框架的判断任务, 考察了听障和听力正常人群空间主导性和空间参照框架的交互作用。结果表明：(1)相对于听力正常人群, 听障人群完成自我参照框架判断任务的反应时更长, 而在完成环境参照框架判断任务无显著差异; (2)听障人群和听力正常人群空间主导性和空间参照框架交互作用呈现出相反模式。研究表明, 听障人群在听力功能受损后, 其空间主导性和空间参照框架的交互作用也产生了变化。     

An observational study of restraint and helmet wearing behaviour in Malaysia

Unrestrained and unhelmeted occupants are at increased risk of severe injury or death in the event of a crash, and there is evidence that children, particularly in low and middle income countries, have low restraint and helmet wearing rates.Roadside observations of occupants of passing vehicles (7247 cars, vans and taxis and 2897 motorcycles) in nearside lanes were made at seven selected road sites located around the Klang Valley (greater Kuala Lumpur) area representing a variety of demographic locations.The findings revealed an overall low rate of seat-belt wearing in vehicles (front seat drivers: 44.6%; front seat adult passengers: 33.8%; front seat child passengers: 11.8%; rear seat adult passengers: 5.2%; and, rear seat child passengers: 5.8%). For motorcyclists, the majority of adult riders and pillions wore helmets (93.4% and 85.8%, respectively), however a substantial proportion (40%) did not fasten their helmet properly. Of children observed on motorcycles, only 30.5% wore helmets.This study shows low seat-belt and helmet wearing rates, despite enactment of legislation that requires all vehicle passengers to be restrained and for all motorcyclists to wear helmets. This was particularly evident for children (front and rear seating positions) and rear seat adult passengers. It is suggested there is a general lack of awareness of safety and the benefits of restraint/helmet use, and lack of adequate and appropriate enforcement. The implications of the findings are discussed in terms of promoting restraint/helmets use, enforcement of legislation and implementation of technologies to increase appropriate restraint/helmet use.     

Judgments for inaccessible targets: Comparing recognition without identification and the feeling of knowing

Both the recognition-without-identification (RWI) and feeling-of-knowing (FOK) paradigms attempt to tap participants?? sense about a target that is inaccessible. In the case of RWI, participants judge the likelihood that the inaccessible target was studied. In the case of FOKs, participants judge the likelihood that the inaccessible target will be recognized at a later point in time. The present study compared the two using a hybrid paradigm. The patterns of responding differed depending on whether the judgment was of the RWI type or the FOK type. For the former, ratings were significantly higher for studied than for unstudied inaccessible targets (the typical RWI effect). For the latter, ratings were significantly lower for studied than for unstudied inaccessible targets (a reversal of the usual RWI effect). Similarity of the targets and distractors diminished the usual RWI effect, but not its reversal in the FOK situation, suggesting that the bases of the two effects differ. A potential explanation is that when participants judge whether an inaccessible target was presented earlier, they are oriented toward relying on cue familiarity, which should be greater for cues of studied targets, whereas when they judge whether they will recognize an inaccessible target later on, they are oriented toward relying on the accessibility of information, which is greater in the unstudied condition, due to the lack of priming of the targets.     

Using verbal and blind-walking distance estimates to investigate the two visual systems hypothesis

Verbal estimates of egocentric distance are usually too short at distances greater than several meters, yet blindfolded walking to previously viewed targets can be surprisingly accurate. We present evidence from three experiments for the existence of two visual pathways with differentencodings of perceived egocentric distance. We found that (1) blind-walking estimates of egocentric distance are consistently more accurate than verbal reports; (2) an indoor versus outdoor environment selectively influences verbal reports; and (3) wearing prism lenses, which displace the visual field vertically, selectively influences the blind-walking estimates. We interpret these results in terms of the two visual systems hypothesis.     

Visual acuity in the pigeon II: effects of target distance and retinal lesions

Visual acuity thresholds for grating targets were determined for three pigeons at target distances ranging from 13 to 73 cm. These measurements were made both while the birds were wearing goggles restricting vision to the frontal field of view and when vision was unrestricted. Using a slightly different method, performance was also compared for target distances of 6 and 13 cm while the goggles were in place. For a second group of three pigeons, acuity data were obtained before and after laser lesions of the retina's foveal region. The findings suggested that acuity was relatively poor for targets at the intermediate distances and that it improved as distance both increased and decreased from these intermediate values. The acuity improvement with increasing distance did not occur, however, when the birds were wearing frontal goggles. The data appear to be consistent with Catania's 1964 suggestion that the pigeon has separate frontal and lateral visual systems that differ in their refractive characteristics. Foveal lesions did not appear to affect acuity for distant targets, and it was concluded that, while the fovea serves the lateral field of view, its presence is not necessary to the static acuity characteristics of this system.     

Safety at first sight? – Manual drivers’ experience and driving behavior at first contact with Level 3 vehicles in mixed traffic on the highway

Soon, manual drivers will interact with conditionally automated vehicles (CAVs; SAE Level 3) in a mixed traffic on highways. As of yet, it is largely unclear how manual drivers will perceive and react to this new type of vehicle. In a driving simulator study with N = 51 participants aged 20 to 71 years (22 female), we examined the experience and driving behavior of manual drivers at first contact with Level 3 vehicles in four realistic driving scenarios (highway entry, overtaking, merging, introduction of a speed limit) that Level 3 vehicles may handle alone once their operational domain extends beyond driving in congested traffic. We also investigated the effect of an external marking via a visual external human–machine interface (eHMI), with participants being randomly assigned to one of three experimental groups (none, correct, incorrect marking). Participants experienced each driving scenario four times, twice with a human-driven vehicle (HDV), and twice with a CAV. After each interaction, participants rated perceived driving mode of the target vehicle as well as perceived safety and comfort. Minimum time headways between participants and target vehicles served as an indicator of safety criticality in the interactions. Results showed manual driver can distinguish CAVs from HDVs based on behavioral differences. In all driving scenarios, participants rated interactions with CAVs at least as safe as interactions with HDVs. The driving data analysis showed that manual driver interactions with CAVs were largely uncritical. However, the CAVs’ strict rule-compliance led to short time headways of following manual drivers in some cases. The eHMI used in this study neither affected the subjective ratings of the manual drivers nor their driving behavior in mixed traffic. Thus, the results do not support the use of eHMIs on the highway, at least not for the eHMI design used in this study.     

The effects of switching between targets on the performance of a simple motor skill

Little direct evidence has emerged regarding the influence of switching between tasks on the performance of skills studied in the motor domain. The present study reported the results of two experiments that examined the effects of task switching on a simple object projection task, which presumably emphasized processes related to response planning and execution. The experimental task required participants to gently tap a knob to make it travel along two parallel rods until it reached a specified target distance. In both experiments, participants in the repeated conditions performed a single target distance while participants in the switched conditions alternated between two target distances. Results indicated that switching between targets degraded accuracy for the two short targets (30cm, Exp. 1; 20cm, Exp. 2). Results were consistent with the preservation of parameter values [Rosenbaum, D. A., Weber, R. J., Hazelett, W. M., & Hindorff, V. (1986). The parameter remapping effect in human performance. Evidence form tongue twisters and finger fumblers. Journal of Memory and Language, 25, 710-725; Sherwood, D. E. (2007). Separate movement planning and spatial assimilation effects in sequential bimanual aiming movements. Perceptual and Motor Skills, 105, 501-513] and suggested an additional role for persisting activation in accounting for spatial assimilation and magnitude effects.     

Control strategies when intercepting slowly moving targets

In 3 experiments, the authors investigated and described how individuals control manual interceptive movements to slowly moving targets. Participants (N = 8 in each experiment) used a computer mouse and a graphics tablet assembly to manually intercept targets moving across a computer screen toward a marked target zone. They moved the cursor so that it would arrive in the target zone simultaneously with the target. In Experiment 1, there was a range of target velocities, including some very slow targets. In Experiment 2, there were 2 movement distance conditions. Participants moved the cursor either the same distance as the target or twice as far. For both experiments, hand speed was found to be related to target speed, even for the very slowly moving targets and when the target-to-cursor distance ratios were altered, suggesting that participants may have used a strategy similar to tracking. To test that notion, in Experiment 3, the authors added a tracking task in which the participants tracked the target cursor into the target zone. Longer time was spent planning the interception movements; however, there was a longer time in deceleration for the tracking movements, suggesting that more visually guided trajectory updates were made in that condition. Thus, although participants scaled their interception movements to the cursor speed, they were using a different strategy than they used in tracking. It is proposed that during target interception, anticipatory mechanisms are used rather than the visual feedback mechanism used when tracking and when pointing to stationary targets.     

Determinants of standard motorcycle safety helmet usage among child pillion riders

The World Health Organization stressed that compliance with the use of safety helmet could significantly reduce the risk of injury by 72% and the probability of death by 39%. In Malaysia, the enforcement of the safety helmet legislation significantly reduced 30% of motorcycle crash fatalities in Malaysia. The aim of this study is to explore the use of motorcycle helmets and the determinants of standard helmet usage among child pillion riders. A cross-sectional survey of 200 adult riders accompanied by the child pillion riders aged 6–12 years old from Klang, Selangor, was conducted. The proper use of the helmet among the respondents and the child pillion riders was observed and recorded. A questionnaire was used to assess socio-demographic background and awareness of the use of child safety helmets. The data was analyzed using SPSS version 23. Only 3% of child pillion riders use standard child safety helmets, while 37% wear standard adult motorcycle helmets. Adult riders who were married, female, always wear helmets, have a higher household income and travel a long distance, are more likely to use a standard motorcycle helmet for their child pillion riders. Knowledge on Standard Certification (SIRIM) label and its importance, awareness of the campaign on child safety helmets, police enforcement, understanding the safety of toy/game helmet use have been identified as additional determinants of standard helmet use among child pillion riders. This study recommends prospective studies with continuous road safety educations programs that integrate behavioural change approaches to enhance the use of standard motorcycle helmets among the child pillion riders in Malaysia.     

Social spatial cognition: social distance dynamics as an identifier of social interactions

We suggest that socio-spatial behavior, which is an interaction between social and spatial cognition, can be viewed as a set of excursions that originate and end in close proximity to another individual(s). We present an extension of earlier studies that perceived spatial behavior in individual animals as a series of excursions originating from a particular location. We measured here the momentary distance between two individuals (social distance) to differentiate among eight possible types of social excursion originating in a state of proximity between excursion-participants. The defined excursion types are based on whether or not the excursion initiator also concludes the excursion, whether or not the excursion starts and ends at the same location, and the dynamics of the distance between excursion participants. We validated this approach to socio-spatial behavior as a set of excursions using it to analyze the behavior of the two sexes in rodents, of normal vs. stereotyped rats, as well as of different rodent species. Each of these groups displays a prevalent excursion type that reflects a distinct social dynamics. Our approach offers a useful and comprehensive tool for studying socio-spatial cognition, and can also be applied to distinguish among different social situations in rodents and other animals.

     

Does energy expenditure affect the perception of egocentric distance? A failure to replicate experiment 1 of Proffitt, Stefanucci, Banton, and Epstein (2003)

In a series of recent studies, Proffitt and his colleagues have reported that the perceived distance to a target is influenced by the energy expenditure associated with any action, such as walking or throwing, for spanning the distance to the target. In particular, Proffitt, Stefanucci, Banton, and Epstein (2003) reported that wearing a heavy backpack caused verbal reports of distance to increase. We conducted a study to determine whether three responses dependent on perceived distance (verbal report of distance, blind walking, and estimates of object size) are influenced by the backpack manipulation. In two experiments, one involving a between-participants design and the other involving a within-participants design, we found that none of the three responses were influenced by the wearing of a heavy backpack.     

Crossed-categorization, evaluation, and face recognition

We investigated the relationship between evaluative intergroup bias and biased errors in intergroup face recognition after crossed-categorization (the combination of two social categories in defining a target of perception). Although evaluative bias and recognition bias often operate in parallel, we draw on two previously unconnected literatures to predict a divergence between these two processes after crossed-categorization. We tested this hypothesis by assessing participants’ evaluations of and recognition of targets who shared two ingroups with participants, targets who shared only one ingroup with participants, and targets who shared neither ingroup. Consistent with predictions, targets’ shared and unshared group memberships combined additively to affect evaluation, but targets who shared two ingroup memberships were better recognized than all other category combinations. These results document the relationship between evaluative bias and recognition bias after crossed-categorization and indicate that crossed-categorization affects evaluative bias and recognition bias in different ways.     

时间压力下图标语义距离对雷达界面信息工作记忆的影响

本研究分别在无时间压力和有时间压力的条件下,通过两个实验探究了图标语义距离?目标数量以及目标类型对雷达界面信息工作记忆的影响?结果发现无时间压力下图标语义距离在工作记忆的编码提取上没有差异,而有时间压力下,强语义图标相较于弱语义图标在工作记忆的提取上具有优势;且无论是在无时间压力下还是有时间压力下,工作记忆容量最佳为3个目标项;对敌机的提取时长于友机长于不明飞行物?结果表明仅在有时间压力下强语义图标在信息提取上具有优势,验证了工作记忆容量的限制,为雷达界面的设计提供了参考意见?     

Birds of a feather sit together: physical similarity predicts seating choice

Across four studies, people sat (or reported they would sit) closer to physically similar others. Study 1 revealed significant aggregation in seating patterns on two easily observed characteristics: glasses wearing and sex. Study 2 replicated this finding with a wider variety of physical traits: race, sex, glasses wearing, hair length, and hair color. The overall tendency for people to sit beside physically similar others remained significant when controlling for sex and race, suggesting people aggregate on physical dimensions other than broad social categories. Study 3 conceptually replicated these results in a laboratory setting. The more physically similar participants were to a confederate, the closer they sat before an anticipated interaction when controlling for sex, race, and attractiveness similarity. In Study 4, overall physical similarity and glasses wearing similarity predicted self-reported seating distance. These effects were mediated by perceived attitudinal similarity. Liking and inferred acceptance also received support as mediators for glasses wearing similarity.