Institut für Psychologie (bis Sept. 2007)
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The Influence of Anticipation and Warnings on Collision Avoidance Behavior of Attentive Drivers
(2012)
This thesis deals with collision avoidance. Focus is on the question of under which conditions collision avoidance works well for humans and if drivers can be supported by a Forward Collision Warning (FCW) System when they do not react appropriately. Forward Collision Warning systems work in a way that tries to focus the driver's attention in the direction of the hazard and evoke an avoidance reaction by some sort of alert (e.g., tone or light). Research on these warning systems generally focuses on inattention and distraction as the cause for crashes. If the driver is inattentive, the results of a crash are thought to be worse as the driver‘s reaction is belated or might not mitigate the crash at all. To ensure effectiveness in the worst case, most of the experiments studying FCW systems have been conducted with visually distracted drivers. Research on the cause and possible countermeasures for crashes of attentive drivers are hardly available, although crash databases and field operational test data show that 40-60% of the drivers look at the forward scene shortly before they crash. Hence, only a few studies elaborated on ideas about the reasons for crashes with attentive drivers. On the basis of the literature, it is worked out that one reason for delayed avoidance behavior can be an incorrect allocation of attention. It is further elaborated that high level attention processes are strongly influenced by interpretation of the situation and the anticipation of future status. Therefore, it is hypothesized that alert drivers react later when they can not foresee a potential threat or even when they misinterpret the situation. If the lack of threat anticipation or incorrect anticipation is a reason for crashes, a FCW system could be a great help, when the FCW is easily comprehensible. It is hypothesized that a FCW can compensate for missing threat anticipation in the driver. The results of the experiments show that the level of threat anticipation has the largest influence on driver behavior in an imminent crash situation. The results further suggest that FCW systems - especially warnings of audible or haptic modality - can help attentive drivers who do not anticipate a threat or misinterpret a situation. The negative influence of missing or mislead threat anticipation on objective measures was small when the threat appeared suddenly. This is thought to be due to the visual appearance of the introduced threat. It is assumed that this type of stimulus triggers a lower level attentional process, as opposed to a top-down attention process controlled by an anticipatory process. In the other scenario types such a lower level process may not be triggered. An important result of the second study is that (Forward) Collision Warnings have to be learned. Participants with warnings reacted slower than participants without any FCW in the first critical event. Participants with a visual warning reacted particularly slow. Later in the experiment, the probands with warnings were constantly faster than their counterparts without them. Hence, the results of this study suggest that a haptic or audible modality should be used as a primary warning to the driver. The characteristic of visual warnings to draw the visual attention is both a blessing and a curse. It is suggested to use the visual warning component for only a short period of time to attract the driver's attention to the forward scene, but then end the display to not further distract him. Car manufacturers try to avoid as many unnecessary alarms as possible. If driver monitoring would be available, it is often planned to suppress warnings when the driver is looking through the windshield. The results suggest not to do so. If a driver reaches a critical situation represented by a low Time-to-collision (TTC) or a high need to decelerate, he should always get a warning, unless he is already braking or steering. The most important arguments for this are: - Looking at the street does not mean that the driver has the correct situational awareness. - The driver has to learn the meaning of the warning. - The driver will not be annoyed by a warning when the situation is considered critical.
A comparative study of diabetics with autonomic neuropathy (N = 13) as against nonneuropathic diabetics (N = 16) and healthy control persons (N = 20) was carried out with respect 10 heart rate both at rest and under stress, frequency of cardiac arrhythmias in a 24-h ECG and accuracy of heartbeat and arrhythmia perception. In the subjects with diabetic autonomic neuropathy, the spontaneaus variability and stress-induced reactivity of the heart rate as weil as the number of tachycardic episodes were reduced, whereas the frequency of ventricular extrasystoles was somewhat increased. Impaired heartbeat perception and a complete Ioss of perception of arrhythmias as a consequence of neuropathic deafferentation could be demonstrated. Cardiac perception disordersalso playavital roJe in other clinical problems, e.g. silent myocardial infarction and Iack of awareness of hypoglycaemia in diabetes mellitus.
ln two experiments, male rats were observed in pairs under different environmental stimulations in an open field. ln Experiment 1, white noise of 85 dB(A) reduced social activities and increased defecation compared to 75 dB(A) and 65 dß(A). ln Experiment 2, the illumination of the open field was varied in addition to a variation of the noise intensity. Again, 85 dB(A) as compared to 50 dB(A) reduced social activities and increased defecation, but also led to changes in non-social behaviours such as sniffing, grooming, and rearing. ln contrast, 400 lx did not differ substantially in its effects from 40 lx in any of the observed behavioural categories. Altogether, the behaviour pattern under 85 dß(A) white noise cannot satisfactorily be explained only by increased anxiety or fear. Alternative explanations are discussed.
Brain potentials during mental arithmetic: effects of extensive practice and problem difficulty
(1994)
Recent behavioral investigations indicate that the processes underlying mental arithmetic change systematically with practice from deliberate, conscious calculation to automatic, direct retrieval of answers from memory [Bourne, L.E.Jr. and Rickard, T.C., Mental calculation: The development of a cognitive skill, Paper presented at the Interamerican Congress of Psychology, San Jose, Costa Rica, 1991; Psychol. Rev., 95 (1988) 492-527]. Results reviewed by Moscovitch and Winocur [In: The handbook of aging and cognition, Erlbaum, Hillsdale, NJ, 1992, pp. 315-372] suggest that consciously controlled processes are more dependent on frontal lobe function than are automatic processes. It is appropriate, therefore to determine whether transitions in the locus of primary brain activity occur with practice on mental calculation. In this experiment, we examine the relationship between characteristics of event-related brain potentials (ERPs) and mental arithmetic. Single-digit mental multiplication problems varying in difficulty (problem size) were used, and subjects were trained on these problems for four sessions. Problem-size and practice effects were reliably found in behavioral measures (RT). The ERP was characterized by a pronounced late positivity after task presentation followed by a slow wave, and a negativity during response indication. These components responded differentially to the practice and problem-size manipulations. Practice mainly affected topography of the amplitude of positivity and offset latency of slow wave, and problem-size mainly offset latency of slow wave and pre-response negativity. Fronto-central positivity diminished from session to session, and the focus of positivity centered finally at centro-parietal regions. This finding suggests that frontal lobe processing is necessary as long as task performance is not automatized, while automatized arithmetic processing requires parietal brain activity only. The pre-response negativity observed in the first session and during more difficult tasks is assumed to reflect excitatory preparatory processes, which could be associated with activation of calculation strategies.
In panic disorder bodily sensations appear to play an important role as a trigger for anxiety. In our psychophysiological model of panic attacks we postulate the following vicious circle: individuals with panic attacks perceive even quite small increases in heart rate and interpret these changes as being catastrophic. This elicits anxiety and a further increase in heart rate. To evaluate this model we conducted a field study of 28 subjects with panic attacks and 20 healthy controls. A 24 hr ambulatory ECG was recorded and the subjects were instructed to report any cardiac perceptions during this period and to rate the anxiety elicited by these perceptions. The incidence of cardiac perceptions was about the same in both groups, but only subjects with panic attacks reported anxiety associated with such perceptions. Analysis of the ECGs revealed that in both groups heart rate accelerations preceded cardiac perceptions. Following cardiac perceptions, the healthy controls showed a heart rate deceleration, whereas the subjects with panic attacks had a further acceleration. This heart rate increase after cardiac perceptions was positively related to the level of anxiety elicited by the perceptions. These results provide clear evidence in support of the vicious circle model of panic attacks.