A Chatziastros

Driving in the Future: Temporal Visuomotor Adaptation and Generalization

Rapid and accurate visuomotor coordination requires tight spatial and temporal sensorimotor synchronization. The introduction of a sensorimotor or intersensory misalignment (either spatial or temporal) impairs performance on most tasks. For more than a century, it has been known that a few minutes of exposure to a spatial misalignment can induce a recalibration of sensorimotor spatial relationships, a phenomenon that may be referred to as spatial visuomotor adaptation. Here, we use a high-fidelity driving simulator to demonstrate that the sensorimotor system can adapt to temporal misalignments on very complex tasks, a phenomenon that we refer to as temporal visuomotor adaptation. We demonstrate that adapting on a single street produces an adaptive state that generalizes to other streets. This shows that temporal visuomotor adaptation is not specific to a single visuomotor transformation, but generalizes across a class of transformations. Temporal visuomotor adaptation is strikingly parallel to spatial visuomotor adaptation, and has strong implications for the understanding of visuomotor coordination and intersensory integration.

Gaze-Eccentricity Effects on Road Position and Steering

The effects of gaze eccentricity on the steering of an automobile were studied. Drivers performed an attention task while attempting to drive down the middle of a straight road in a simulation. Steering was biased in the direction of fixation, and deviation from the center of the road was proportional to the gaze direction until saturation at approximately 15 degrees gaze-angle from straight ahead. This effect remains when the position of the head was controlled and a reverse-steering task was used. Furthermore, the effect was not dependent on speed but reversed when the forward movement of the driver was removed from the simulation. Thus, small deviations in a drivers gaze can lead to significant impairments of the ability to drive a straight course.

The role of visual and nonvisual feedback in a vehicle steering task

This article investigates vehicle steering control, focusing on the task of lane changing and the role of different sources of sensory feedback. Participants carried out 2 experiments in a fully instrumented, motion-based simulator. Despite the high level of realism afforded by the simulator, participants were unable to complete a lane change in the absence of visual feedback. When asked to produce the steering movements required to change lanes and turn a corner, participants produced remarkably similar behavior in each case, revealing a misconception of how a lane-change maneuver is normally executed. Finally, participants were asked to change lanes in a fixed-based simulator, in the presence of intermittent visual information. Normal steering behavior could be restored using brief but suitably timed exposure to visual information. The data suggest that vehicle steering control can be characterized as a series of unidirectional, open-loop steering movements, each punctuated by a brief visual update.

Visual object detection, categorization, and identification tasks are associated with different time courses and sensitivities.

Recent evidence suggests that the recognition of an objects presence and its explicit recognition are temporally closely related. Here we re-examined the time course (using a fine and a coarse temporal resolution) and the sensitivity of three possible component processes of visual object recognition. In particular, participants saw briefly presented (Experiment I to III) or noise masked (Experiment IV) static images of objects and non-object textures. Participants reported the presence of an object, its basic level category, and its subordinate category while we measured recognition performance by means of accuracy and reaction times. All three recognition tasks were clearly separable in terms of their time course and sensitivity. Finally, the use of a coarser temporal sampling of presentation times decreased performance differences between the detection and basic level categorization task suggesting that a fine temporal sampling for the dissociation of recognition performances is important. Overall the three probed recognition processes were associated with different time courses and sensitivities.

The impact of coping style on gaze duration.

The understanding of individual differences in response to threat (e.g., attentional bias) is important to better understand the development of anxiety disorders. Previous studies revealed only a small attentional bias in high-anxious (HA) subjects. One explanation for this finding may be the assumption that all HA-subjects show a constant attentional bias. Current models distinguish HA-subjects depending on their level of tolerance for uncertainty and for arousal. These models assume that only HA-subjects with intolerance for uncertainty but tolerance for arousal (“sensitizers”) show an attentional bias, compared to HA-subjects with intolerance for uncertainty and intolerance for arousal (“fluctuating subjects”). Further, it is assumed that repressors (defined as intolerance for arousal but tolerance for uncertainty) would react with avoidance behavior when confronted with threatening stimuli. The present study investigated the influence of coping styles on attentional bias. After an extensive recruiting phase, 36 subjects were classified into three groups (sensitizers, fluctuating, and repressors). All subjects were exposed to presentations of happy and threatening faces, while recording gaze durations with an eye-tracker. The results showed that only sensitizer showed an attentional bias: they gazed longer at the threatening face rather than at the happy face during the first 500 ms. The results support the findings of the relationship between anxiety and attention and extend these by showing variations according to coping styles. The differentiation of subjects according to a multifaceted coping style allows a better prediction of the attentional bias and contributes to an insight into the complex interplay of personality, coping, and behavior.

Spatial partitioning during visual search of a dyad

General: Standard visual search: Find T among Ls. Two participants, seated side-by-side, respond simultaneously via button press. 400 trials with 50% target occurrence. 1.80 m distance to 2.2 m wide screen (60° x 50° FOV). Central 500 ms fixation followed by max. 4 sec presentation. T appears in 5 rows x 4 columns matrix. Noise-reduction headphones. No communication allowed. General instruction: “as fast and as accurate as possible”.

Gaze-eccentricity effects on automobile driving performance - or - Going where you look

1 Morris, G.H. (1990). Hunter seat equitation (3rd ed.). New York, NY: Doubleday. 2 Motorcycle Safety Foundation. (1992). Evaluating, coaching, and range management instructors guide. Irvine, CA: Author. 3 Bondurant, R. & Blakemore, J. (1998). Bob Bondurant on high performance driving. Osceola WI: Motorbooks International. 4 Cutting, J.E. & Readinger, W.O. (Submitted). Walking, looking to the side, and taking curved paths. Methods Results

Joint and individual walking in an immersive collaborative virtual environment

The aim of this experiment was to determine to which extent humans optimize their walking behavior in different conditions while navigating in a virtual maze. In two conditions participants either walked individually or jointly connected - carrying a physical stretcher. The results showed that an extra effort due to the task-required cooperation was split evenly within the group, even though the sensory feedback about the physical and social environment was significantly different for leader (e.g. was not able to see the follower) and follower (e.g. was able to see the leader). These results might indicate the emergence of a joint body: a phenomenon in which two individual action-perception loops are tuned towards each other in order to optimize a common goal.