Behavioural adaptation and effectiveness of a Forward Collision Warning System depending on a secondary cognitive task

Forward Collision Warning Systems (FCWS) have been designed to enhance road safety by reducing the number of rear-end collisions. Nevertheless, little is known about how drivers adapt their behaviour over time when using this kind of system. In addition, these systems are expected to aid particularly distracted drivers. However, previous research has suggested that the effectiveness of the system could depend on the difficulty level of the secondary task. The objective of this study on driving simulator was twofold. Firstly, it consisted in evaluating the behavioural adaptation to an FCWS as well as analysing the possible consequences of driving without the system after a short period of adaptation. Secondly, it was to evaluate the effectiveness of the system according to two different difficulty levels of a cognitive secondary task. The results showed that drivers adapted their behaviour positively when the system was introduced. Nevertheless, both the effectiveness and the behavioural adaptation in the short term were dependent on the cognitive load induced by the secondary task. These findings suggest that the warning needs some attentional resources to be processed. Finally, no negative or transfer effect was observed following the removal of the system after a short period of adaptation.     

认知负荷与编码方式影响小学数学学业不良生的前瞻记忆及其成分

通过两个实验探讨认知负荷对小学数学学业不良生前瞻记忆及其成分的影响, 以及是否可以通过执行意向编码提高其前瞻记忆及其成分的成绩。实验1结果显示数学学业不良生前瞻记忆、前瞻成分及回溯成分正确率显著低于数学学优生, 高认知负荷条件前瞻记忆、前瞻成分及回溯成分的正确率显著低于低认知负荷条件; 实验2结果显示执行意向编码条件下, 数学学业不良生前瞻记忆成绩显著好于标准编码条件, 前瞻成分和回溯成分的正确率高于标准编码条件。结果表明数学学业不良生前瞻记忆及其成分表现差于数学学优生; 无论认知负荷高低, 执行意向编码均可通过提升前瞻成分和回溯成分改善数学学业不良生前瞻记忆表现。     

Cognitive load while driving impairs memory of moving but not stationary elements within the environment

The negative impact of cognitive load, such as cell phone conversations, while driving is well established, but understanding the nature of this performance deficit is still being developed. To test the impact of load on awareness of different elements in a driving scene, memory for items within the environment was examined under load and no load conditions. Participants drove through two different scenarios in a driving simulator, were periodically interrupted by a pause in the driving during, and were asked questions regarding moving and stationary objects in the environment. Participants in the load condition drove while concurrently counting backwards by sevens. Results indicate that driving under load conditions led to diminished knowledge of moving, but not stationary, objects in the scene. This result suggests not all types of knowledge are equally impaired. Potential implications for current theories of cell phone use while driving and applied attention theory are discussed.     

Central load reduces peripheral processing: Evidence from incidental memory of background speech

Is there a trade‐off between central (working memory) load and peripheral (perceptual) processing? To address this question, participants were requested to undertake an n‐back task in one of two levels of central/cognitive load (i.e., 1‐back or 2‐back) in the presence of a to‐be‐ignored story presented via headphones. Participants were told to ignore the background story, but they were given a surprise memory test of what had been said in the background story, immediately after the n‐back task was completed. Memory was poorer in the high central load (2‐back) condition in comparison with the low central load (1‐back) condition. Hence, when people compensate for higher central load, by increasing attentional engagement, peripheral processing is constrained. Moreover, participants with high working memory capacity (WMC) – with a superior ability for attentional engagement – remembered less of the background story, but only in the low central load condition. Taken together, peripheral processing – as indexed by incidental memory of background speech – is constrained when task engagement is high.     

IAT范式下自尊内隐性的再证明

该研究用IAT测量了被试的内隐自尊,并通过操纵被试在不同的认知负荷条件下进行外显自我评价来考察外显自我评价和内隐自尊之间的关系。得到的结论是,在低认知负荷条件下进行外显自我评价时,外显自我评价和内隐自尊没有表现出一致性;在高认知负荷条件下进行外显自我评价时,外显自我评价和内隐自尊表现出一致性。该研究在IAT范式下表明了内隐自尊和外显自尊的分离,内隐自尊具有无意识性和自动化的特点。     

间隔时间及记忆负荷对信息缺失错误记忆的影响

现场中的信息缺失会影响人类对事件的记忆,这对证人证言研究是非常重要的,但以往对之却鲜有研究.本研究以大学生为被试,运用信息缺失范式,采用视频录像材料,通过2个实验探讨了间隔时间和记忆负荷对错误记忆的影响.结果表明:(1)间隔时间没有影响真实记忆和错误记忆,但信心水平却随着间隔时间的延长而变化;(2)记忆负荷高低没有影响真实记忆却影响了错误记忆,在关键信息呈现条件下,降低记忆负荷可以减少错误记忆的发生;(3)信息性质会影响人们的记忆,关键信息呈现条件下的错误记忆和真实记忆均高于关键信息缺失的条件.     

Experience Influences Affordance Perception for Low Crawling Under Barriers With Altered Body Dimensions

Abstract

We examined the role of experience in affordance perception for low crawling with altered body dimensions under barriers of different heights. Adults decided which of five backpacks (10–30?cm thick) they would be able to wear while low crawling under barriers. Participants were assigned to one of three experience conditions. Participants in the Pre/Post-choice experience condition crawled under the barrier before and after picking a backpack, participants in the Feedback condition crawled under the barrier after picking a backpack, but participants in the No Experience condition received no low-crawling experience. Past research suggests that pre-choice experience with low crawling under the barrier would lead to more accurate responses. Overall, participants in all three conditions scaled the height of the backpack to the barrier height. Pre-choice low-crawling experience strongly influenced backpack choices such that participants in the Pre/Post condition picked significantly smaller backpacks and produced fewer failures than participants in the other conditions. The results provide evidence that brief practice, in an unfamiliar posture, can lead to improvements in affordance perception.     

Effects of Varying Load Conditions on the Organization of Postural Adjustments during Voluntary Arm Flexion

One purpose of the experiments reported here was to further clarify the effect of varying loads on postural adjustments. Another was to reevaluate whether or not the timing of electromyographic (EMG) activity in the postural muscle is preprogrammed. To accomplish these goals, we compared the effect of the presence or absence of prior knowledge of a load on the timing of EMG activity in the postural muscle (biceps femoris [BF]) with that in the focal muscle (anterior deltoid [AD]). Although the sequence of EMG activation was similar under conditions with and without a load, the timing of postural EMG activities (BFi, ipsilateral BF; BFc, contralateral BF) in associated postural adjustments was dependent on the force of arm movement, and the latencies of postural EMG activities (BFi—BFc) were dependent on the speed of arm movement. This indicates that EMG changes in the upper (focal muscle) and lower limbs (postural muscle) were triggered by different motor programs. Moreover, similar EMG activities were observed in postural muscles when the subject had advance knowledge of the presence or the absence of a load. Thus, this suggests that BFi may be centrally preprogrammed (anticipatory regulation) and BFc may be feedback regulated. Furthermore, environmental information may be a critical source of influence on those postural responses.     

Shoulder Joint Position Sense Improves With External Load

Joint position sense (JPS) is important in the maintenance of optimal movement coordination of limb segments in functional activities. Researchers have shown that the sensitivity of musculotendinous mechanoreceptors increases as muscle activation levels increase. In the present study, when 25 participants tried to replicate the same presented position, both vector and elevation angle repositioning errors decreased linearly as the external load increased up to 40% above unloaded shoulder torque. However, external load had no effect on plane repositioning error. The results indicated that JPS increased under conditions of increasing external load but only in the direction of the applied load. That finding indicates that JPS acuity improves as muscle activation levels increase.     

Age-Related Changes in Grip Force and Dynamics of Hand Movement

The authors investigated whether older adults (n = 16; mean age = 65 years) increased grip force to compensate for load force fluctuations during up and down movements more than young adults did (n = 16; mean age = 24 years) and whether older and young adults exhibited similar adaptation of grip force to alterations in friction associated with changes in object surface texture. As previously reported, older adults used a higher level of grip force than young adults during static holding. Increased grip force was observed in the older group during movement. The increase was appropriate to the lower coefficient of friction estimated for the older group. In both groups, grip force was greater with a smooth than with a rough surface (the latter having the higher coefficient of friction) during static holding and during movement. Moreover, grip force modulation was equally well synchronized with load force fluctuation during movement in the two groups. The authors concluded that changes in organization of grip force with age are well adapted to change in hand-object interface properties. Elevated grip force in older adults does not necessarily signify a fundamental change in synchronizing grip force modulation with load force fluctuation.