Stefan Ladwig

Intra- and intermodal integration of discrepant visual and proprioceptive action effects

Integration of discrepant visual and proprioceptive action effects puts high demands on the human information processing system. The present study aimed to examine the integration mechanisms for the motor (Exp. 1) and visual modality (Exp. 2). According to theories of common coding, we assumed that visual as well as proprioceptive information is represented within the same cognitive domain and is therefore likely to affect each other (multisensory cross talk). Thus, apart from the often-confirmed visual dominance in multisensory integration, we asked about intra- and intermodal recall of either proprioceptive or visual information and whether there were any differences between the motor and visual modality. In a replication paradigm, we perturbed the relation between hand movements and cursor movements. The task required the (intra- vs. intermodal) replication of an initially performed (seen) hand (cursor) movement in a subsequent motor (visual) replication phase. First, mechanisms of integration were found to be dependent on the output modality. Visual action effects interfered the motor modality, but proprioceptive action effects did not have any effects on the visual modality. Second, however, intermodal integration was more susceptible to interference, and this was found to be independent from the output modality. Third, for the motor modality, the locus of perturbation (perturbation of cursor amplitude or perturbation of hand amplitude) was irrelevant, but for the visual modality, perturbation of hand amplitudes reduced the cross talk. Tool use is one field of application of these kinds of results, since the optimized integration of conflicting action effects is a precondition for using tools successfully.

Age Effects on Controlling Tools with Sensorimotor Transformations

Controlling tools in technical environments bears a lot of challenges for the human information processing system, as locations of tool manipulation and effect appearance are spatially separated, and distal action effects are often not generated in a 1:1 manner. In this study we investigated the susceptibility of older adults to distal action effects. Younger and older participants performed a Fitts’ task on a digitizer tablet without seeing their hand and the tablet directly. Visual feedback was presented on a display in that way, that cursor amplitude and visual target size varied while the pre-determined hand amplitude remained constant. In accordance with distal action effects being predominant in controlling tool actions we found an increase in hand movement times and perceptual errors as a function of visual task characteristics. Middle-aged adults more intensely relied on visual feedback than younger adults. Age-related differences in speed-accuracy trade-off are not likely to account for this finding. However, it is well known that proprioceptive acuity declines with age. This might be one reason for middle-aged adults to stronger rely on the visual information instead of the proprioceptive information. Consequently, design and application of tools for elderly should account for this.

Mirrored visual feedback limits distal effect anticipation

Modern tools in technological environments are often characterized by a spatial separation of hand actions (operating a remote control) and their intended action effects (displayed movements of an unmanned vehicle, a robot, or an avatar on a screen). Often non-corresponding proximal and distal movement effects put high demands on the human information processing system. The present study aimed to investigate how modern technological environments influence processes of planning and controlling actions. Participants performed ipsi- or contralateral movements in response to colored stimuli, while the stimulus location had to be ignored. They did not see the stimuli and hands directly, but received visual feedback (with retained or reversed spatial relations) on a projection screen in front of them. Visual feedback retaining spatial relations led to the usual Simon effect. However, visual feedback reversing spatial relations inverted the Simon effect in ipsilateral responses, and eliminated it in contralateral responses (Exp. 1). Impairing the proximal movement-effect loop so that proprioceptive/tactile information from the moving hand was no longer a reliable source for planning and controlling actions attenuated compatibility effects (Exp. 2). Moreover, distal action effects predominated action control even for opposing body-related effects. It seemed that action control of transformed movements depended on the reliability of proprioceptive/tactile and visual information. When the amount of feature overlap between proprioception and vision was low and proprioceptive (visual) information was no longer reliable, then distal (proximal) action effects stepped forward and became crucial in controlling transformed actions.

Improving touch accuracy on large tabletops using predecessor and successor

Touch interfaces provide great flexibility in designing an UI. However, the actual experience is often frustrating due to bad touch recognition. On small systems, we can analyze yaw, roll, and pitch of the finger to increase touch accuracy for a single touch. On larger systems, we need to take additional factors into account as users have more flexibility for their limb posture and need to aim over larger distances. Thus, we investigated how people perform touch sequences on those large touch surfaces. We show that the relative location of the predecessor of a touch has a significant impact on the orientation and position of the touch ellipsis. We exploited this effect on an off-the-shelf touch display and showed that with only minimal preparation the touch accuracy of standard hardware can be improved by at least 7%, allowing better recognition rates or more UI components on the same screen.

Better (not) Charge in Your Garage! Perceived Benefits and Optimal Positioning of Public Fast Charging Infrastructure for Electrical Vehicles from User’s Perspective

In order to increase the number of electrical vehicles (EV) in Germany, a nationwide distribution of public charging stations is intended to improve the perception of EV usage potential. These can be equipped with novel fast charging technology. To examine the users’ needs and deduce potential locations for charging stations, users of EV are interviewed with focus on acceptance of detours, the necessary back-up battery SOC (state of charge), and, as conclusion of both, the user’s preference for home or public charging. Finalizing, factors of perceived effort and perceived benefit in public charging are evaluated. It can be shown that the positioning of public charging is not yet sufficient, but has to be improved. This can be deducted from the backed-up battery SOC which is left to manage long detours to public charging infrastructure.

Inverting Traditional Views on Human Task-Processing Behavior by Focusing on Abilities Instead of Disabilities --- A Discussion on the Functional Situation Management of Drivers to Solve Demanding Situations

Due to the well-elaborated limitations of cognitive processing, humans can process only a certain number of tasks in parallel. Notably in the context of driving this poses a serious problem when performing additional tasks while driving. Statistically, drivers perform other tasks while driving in over 50i¾?% of the time but drive approximately 3.8i¾?million kilometers before experiencing a severe accident. Hence, besides the undoubted negative influence of non-driving related tasks on driving, appropriate abilities are required to succeed even in most critical driving situations. Until today, little is known about these abilities. To gain further insight, the present paper dwells on the development of a framework based on elaborated cognitive models. Its central claim concerns proactive functional situation management based on situation assessment and task prioritization. A driving simulation study is reported to support the framework. Further, it is discussed how this approach could be applied to fields of HMI.

Complexity of sensorimotor transformations alters hand perception

When using tools effects in body space and distant space often do not correspond or are even in conflict. The ideomotor principle holds that actors select, initiate and execute movements by activating the anticipatory codes of the movements’ sensory effects (Greenwald, 1970; James, 1890). These may be representations of body-related effects and/or representations of more distal effects. Previous studies have demonstrated that distant action effects dominate action control, while body-related effects are attenuated (e.g., Musseler and Sutter, 2009). In two experiments, participants performed closed-loop controlled movements on a covered digitizer tablet to control a cursor on a monitor. Different gains perturbed the relation between hand and cursor amplitude, so that the hand amplitude varied and the cursor amplitude remained constant, and vice versa. Within a block the location of amplitude perturbation randomly varied (low predictability) or not (high predictability). In Experiment 1 both trajectories of hand and cursor followed the same linear path, in Experiment 2 a linear hand trajectory produced a curved cursor trajectory on the monitor. When participants were asked to evaluate their hand movement, they were extremely uncertain about their trajectories. Both, predictability of amplitude perturbation and shape of cursor trajectory modulated the awareness of one’s own hand movements. We will discuss whether the low awareness of proximal action effects originates from an insufficient quality of the humans’ tactile and proprioceptive system or from an insufficient spatial reconstruction of this information in memory.