Biology subjects

Fiehler, K.

Publications and source records attributed to Fiehler, K..

16 recordsLinked to original sources

bioRxiv2026

When Brands Take a Stand: Evidence from Eye-Movements and Memory Recognition

Brands increasingly express their positions on social issues through advertising, social media, and public campaigns. How such messages shape consumer perception is an ongoing area of investigation. Addressing a gap in brand activism research in marketing, this study uses eye- tracking technology to examine its impact on brand attitude, eye movement behavior, and memory retention. We tested these variables across three experimental tasks: an online survey, a free- viewing task, and a surprise memory recognition test. As a result, disagreement increased reading time for text statements, while agreement increased visual engagement (fixations) with the depicted product. Positive brand attitude also enhanced memory recognition for advertisements. Overall, disagreement appears to trigger effortful processing of conflicting information, while agreement facilitates visual absorption and strengthens product recognition. These findings highlight the cognitive risks and rewards of brand activism and provide a foundation for future research on its underlying perceptual and cognitive mechanisms.

neuroscience↗

bioRxiv2026

Tactile suppression during movement as optimal integration of somatosensory feedback across time

Goal-directed movements generate tactile signals from the moving body, yet many are perceptually suppressed. Prevailing accounts propose that the nervous system reduces tactile sensitivity by prioritizing internal predictions over somatosensory feedback, contrasting with the view that suppression reflects peripheral masking. However, both accounts lack quantitative explanations of temporal dynamics and dependence on the motor task. Here, we show that tactile suppression is a consequence of optimal state estimation during movement. Using optimal feedback control theory, we derived how the nervous system should dynamically weight uncertain internal predictions against noisy somatosensory feedback. Human participants performed goal-directed reaching movements while vibrotactile stimuli were delivered at different time points. Suppression weakened as internal uncertainty about hand distance to target increased, consistent with greater reliance on sensory feedback. Model comparison identifies tactile suppression as dynamic, uncertainty-dependent state estimation rather than peripheral masking, establishing a normative principle for tactile sensitivity during action.

neuroscience↗

bioRxiv2026

Temporal dynamics of early somatosensory processing in goal-directed actions

Tactile sensitivity is temporally modulated on a moving limb. Yet the neural mechanisms underlying this modulation remain unclear. Using electroencephalography, we examined the temporal dynamics of early somatosensory processing during goal-directed reaching. Participants reached for their unseen left hand while brief vibrations were applied to the moving right index finger in different movement phases. Psychophysical results revealed overall tactile suppression during reaching, with sensitivity transiently improving around maximum speed relative to the late movement phase. Consistent with the psychophysical data, the short-latency P45 component, originating in primary somatosensory cortex, was suppressed during reaching but recovered around maximum speed. Reduced P45 amplitudes were associated with stronger tactile suppression measured behaviorally, linking early cortical activity to perceptual changes. This temporally specific modulation of tactile perception, associated with early cortical processing, suggests that the somatosensory system dynamically adapts its sensitivity to facilitate sensorimotor control in goal-directed actions. Significance statementThe perception of touch on a moving hand varies across different movement phases, depending on the importance of sensory feedback for guiding the hand. Our results show that these changes in perception are linked to modulations in early brain activity, indicating that the central nervous system adjusts touch processing in a time-sensitive manner at early processing stages to facilitate control of goal-directed actions.

neuroscience↗

bioRxiv2025

Modulation of tactile sensitivity in the lower limbs during goal-directed movements

Tactile sensitivity drops in a moving than static limb due to a combination of central, predictive mechanisms and peripheral effects. This suppression is dynamically modulated during movement, as shown during upper-limb actions, yet little is known about its implication during complex lower-limb movements. We investigated tactile sensitivity during naturalistic kicking by delivering vibrotactile probe stimuli to the balancing and kicking feet at different movement phases. In Experiment 1, participants kicked a suspended ball while tactile sensitivity was probed at movement onset, mid-swing, ball contact, and after-contact. Results revealed distinct modulation patterns in each foot. When transitioning from bipedal to unipedal stance, tactile processing at the balancing foot was particularly suppressed but at the kicking foot it improved, suggesting concurrent modulation across the two legs depending on their motor function. Tactile sensitivity remained rather invariant at other time points, but was strongly suppressed on the kicking foot at the moment of ball contact. The strength of this suppression correlated with kicking speed, which could reflect either stronger predictive control or stronger peripheral processes that mask the vibrotactile probe. To test these, a new set of participants held their foot still while a ball collided with it at high or low speed. Suppression was greater with faster ball contacts, revealing that peripheral processes can modulate tactile processing. These findings show that lower-limb tactile sensitivity during goal-directed leg movements can be concurrently modulated across the legs, presumably reflecting an interplay between central sensorimotor processes guiding the movement and peripheral processes affecting sensitivity. Significance StatementTactile sensitivity is known to fluctuate during movement, but little is understood about how it is tuned during complex lower-limb actions. Using a naturalistic ball-kicking task, we reveal distinct modulation patterns in the balancing and kicking feet, showing that postural and guiding demands dynamically shape tactile sensitivity. We further demonstrate that the strength of tactile modulation is influenced by peripheral processes, such as tactile masking. These findings highlight that lower-limb tactile processing can be flexibly and concurrently modulated in the two legs during state transitions that impose different sensorimotor demands for complex natural behavior.

neuroscience↗

bioRxiv2025

Head engagement during visuomotor tracking is determined by postural demands and aging

Vision is important for various tasks, from visually tracking moving objects to maintaining balance. People obtain visual information through eye movements performed either alone or in combination with head movements. Even when isolated eye movements can accommodate the amplitude of the desired gaze shift, humans still perform head movements, as they provide additional sensory signals that can be integrated with retinal input resulting in improved gaze estimates. However, head movements also create mechanical torques and attenuate vestibular processing that could disturb balance. We, therefore, here examined whether head engagement is determined by postural requirements when performing a visual tracking task. Young participants visually tracked a target moving horizontally along different amplitudes, while they were seated, standing on a firm and an unstable surface. Our results showed stronger head engagement when standing than sitting, but no systematic differences were found between firm and unstable surfaces. To further explore the interplay between head engagement and postural demands, we conducted a second experiment where young and older participants performed a similar task, but now they were either allowed to move their head or instructed to limit their head movements. Both tracking accuracy and postural sway increased when engaging the head. When asked to limit head movements, both age groups engaged their head minimally, but head movements were more pronounced in more challenging postures. When allowed to move their head naturally, younger participants engaged their head more when standing than sitting, but older adults reduced their head movements with more demanding postures. We suggest that head movements in younger adults facilitate visual tracking, while limited head movements in older adults preserve balance.

neuroscience↗

bioRxiv2024

Postural demands modulate tactile perception in the lower limb in young and older adults

Balance control requires constant integration of feedforward and feedback signals. In healthy aging, the quality of feedback signals decreases while feedforward control is upweighted; but it is unclear how tactile perception is modulated when balance control is challenged and how this interacts with age-related changes in sensorimotor processes. We therefore examined tactile perception in standing when confronted with different postural demands in young and older adults. To this end, we measured tactile sensitivity on the calf during sitting (baseline), standing on solid ground, and standing on unstable ground (foam). We also measured the center of pressure during standing using a force plate and calculated a 95% confidence ellipse area and the center of pressure length. Tactile sensitivity was assessed by fitting a psychometric function to verbal responses for detecting vibrotactile probes, calculating the detection threshold at 50% detection, and normalizing the two standing conditions to baseline. We examined the effect of age and postural demands on the center of pressure kinematics and detection thresholds. We found higher sway and poorer tactile sensitivity when standing on foam irrespective of age. The increase of postural demands seems to reduce the reliance on tactile feedback signals from the lower limbs in both young and older adults. Our results suggest that postural demands challenge healthy agers as young adults, probably leading to a down-weighting of tactile feedback processing.

neuroscience↗

bioRxiv2024

Reliability of tactile perception and suppression measurements

Tactile signals arising on ones own body allow estimation of ones own sensory state and foster interactions with the environment. However, tactile perception can be influenced by various factors. For instance, tactile perception is suppressed on a moving limb compared to when it is resting, a phenomenon termed tactile suppression. Here we examine whether tactile perception during resting and during movement is robust over shorter and longer time intervals. Participants had to detect tactile stimuli of various intensities on their index finger while this finger was resting or moving (finger extension). This detection task was performed on four sessions at separate days across a period of one month. We found that tactile perception during resting is robust within single sessions and across days. However, tactile perception during movement changed across days, but these changes lacked a clear systematic pattern. We further show that temporal changes in perception alone cannot fully account for the previously reported tactile suppression effects. Finally, split-half correlations reveal high consistency in the estimated perceptual measures, demonstrating that estimates of tactile perception are robust across measurement points.

physiology↗

bioRxiv2023

Visual perturbations temporally tune balance retention and associated tactile processing

Somatosensory feedback is essential for motor control, yet sensations from ones own movements are often suppressed. Despite extensive research on movement-induced tactile suppression, its mechanisms remain unclear. Most studies focus on simple upper-limb movements, leaving the generalization to other body parts unexplored. This study examines tactile processing on the lower limb during balance control by varying feedback processing demands. Participants experienced visual perturbations in a virtual room challenging their posture. Tactile sensitivity was assessed using vibrotactile stimuli to the lower leg at different times around the perturbation. We found that postural behavior is both predictively tuned before and reactively adjusted to expected perturbations. Our results provide evidence that tactile sensitivity changes according to feedback processing demands on the lower limb. Such dynamic sensory modulation could reflect the continuous up- and down-regulation of feedback signals to accomplish the task at hand.

neuroscience↗

bioRxiv2023

Egocentric cues influence the spatial memory of landmark configurations for memory-guided actions

Allocentric and egocentric reference frames are used to determine the spatial position of action targets in reference to objects in the environment, i.e., landmarks (allocentric), or the observer (egocentric). Previous research investigated reference frames in isolation, for example, by shifting landmarks relative to the target and asking participants to reach to the remembered target location. Systematic reaching errors were found in the direction of the landmark shift and used as a proxy for allocentric spatial coding. Here we examined the interaction of both allocentric and egocentric reference frames by shifting the landmarks as well as the observer. We asked participants to encode a 3D configuration of balls, and to reproduce this configuration from memory after a short delay followed by a landmark or observer shift. We also manipulated the number of landmarks to test its effect on the use of allocentric and egocentric reference frames. Shifting the observer resulted in larger configurational errors. In addition, an increase in the number of landmarks led to a stronger reliance on allocentric cues and a weaker contribution of egocentric cues. In sum, our results highlight the important role of egocentric cues for allocentric spatial coding in the context of memory-guided actions. New & NoteworthyObjects in our environment are coded relative to each other (allocentrically) and are thought to serve as independent and reliable cues (landmarks) in the context of unreliable egocentric signals. Contrary to this assumption, we demonstrate that egocentric cues alter the spatial memory of landmark configurations, which could reflect recently discovered interactions between allocentric and egocentric neural processing pathways. Further, additional landmarks lead to a higher contribution of allocentric and a lower contribution of egocentric cues.

neuroscience↗

bioRxiv2023

Sensorimotor memories influence movement kinematics but not associated tactile processing

When interacting with objects, we often rely on visual information. However, vision is not always the most reliable sense for determining relevant object properties. For example, when the mass distribution of an object cannot be inferred visually, humans may rely on predictions about the objects dynamics. Such predictions may not only influence motor behavior but also associated somatosensory processing, as sensorimotor predictions lead to reduced tactile sensitivity during movement. We examined whether predictions based on sensorimotor memories influence grasping kinematics and associated tactile processing. Participants lifted an object of unknown mass distribution and reported whether they detected a tactile stimulus on their grasping hand during the lift. In Experiment 1, the mass distribution could change from trial to trial, whereas in Experiment 2, we intermingled longer with shorter parts of constant and variable mass distributions, while also providing implicit or explicit information about the trial structure. In both experiments, participants grasped the object by predictively choosing contact points that would compensate the mass distribution experienced in the previous trial. Tactile suppression during movement, however, was invariant across conditions. These results suggest that predictions based on sensorimotor memories can influence movement kinematics but may not affect associated tactile perception. Public significance statementTo perform a goal-directed movement, such as grasping an object, humans combine the available sensory information with predictions about the prevailing dynamics. Sensorimotor predictions also lead to a decrease of movement-related tactile signals, a phenomenon termed tactile suppression. Tactile suppression is supposed to rely on a dynamic weighting of sensory feedback and predictive signals. When sensory feedback is not reliable, reliance on memory-based predictions may be desired. Here we show that motor behavior is influenced by predictions based on sensorimotor memories, but associated tactile processing appears to be robust.

neuroscience↗

bioRxiv2023

Pupil dilation scales with movement distance of real but not of imagined reaching movements

Pupillary responses have now been reliably identified for cognitive and motor tasks, but less is known about their relation to mentally simulating movements (known as motor imagery). Previous work found pupil dilations during the performance of simple finger movements, where peak pupillary dilation scaled with the complexity of the finger movement and force required. Recently, pupillary dilations were reported during imagery of grasping and piano playing. Here we examined whether pupillary responses are sensitive to the dynamics of the underlying motor task for both executed and imagined reach movements. Participants reached or imagined reaching to one of three targets placed at different distances from a start position. Both executed and imagined movement times scaled with target distance, and they were highly correlated, confirming previous work and suggesting that participants did imagine the respective movement. Increased pupillary dilation was evident during motor execution compared to rest, with stronger dilations for larger movements. Pupil dilations also occurred during motor imagery, however they were generally weaker than during motor execution and they were not influenced by imagined movement distance. Instead, dilations during motor imagery resembled pupil responses obtained during a non-motor imagery task (imagining a previously viewed painting). Our results demonstrate that pupillary responses can reliably capture the dynamics of an executed goal-directed reaching movement, but suggest that pupillary responses during imagined reaching movements reflect general cognitive rather than motor-specific components of the motor imagery process. New and noteworthyPupil size is influenced by the performance of cognitive tasks. Here we demonstrate that pupil size increases during execution and mental simulation of goal-directed reaching movements compared to rest. Pupil dilations scale with movement amplitude only during motor execution, whereas they are similar during motor imagery and a non-motor imagery, cognitive task.

neuroscience↗

bioRxiv2021

Crossmodal metaperception: Visual and tactile confidence share a common scale

Perceptual decisions are typically accompanied by a subjective sense of (un)certainty. There is robust evidence that observers have access to a reliable estimate of their own uncertainty and can judge the validity of their perceptual decisions. However, there is still a debate to what extent these meta-perceptual judgements underly a common mechanism that can monitor perceptual decisions across different sensory modalities. It has been suggested that perceptual confidence can be evaluated on an abstract scale that is not only task-independent but also modality-independent. We aimed to scrutinize these findings by measuring visual contrast and tactile vibration discrimination thresholds in a confidence forced-choice task. A total of 56 participants took part in our study. We determined thresholds for trials in which perceptual decisions were chosen as confident and for those that were declined as confident. Confidence comparisons were made between perceptual decisions either within the visual and tactile modality, respectively, or across both modalities. Furthermore, we assessed executive functions to explore a possible link between cognitive control and meta-perceptual capacities. We found that perceptual performance was a good predictor of confidence judgments and that the threshold modulation was similarly pronounced in both modalities. Most importantly, participants compared their perceptual confidence across visual and tactile decisions with the same precision as within the same modality. Cognitive control capacities were not related to meta-perceptual performance. In conclusion, our findings corroborate that perceptual uncertainty can be accessed on an abstract scale, allowing for confidence comparisons across sensory modalities.

neuroscience↗

bioRxiv2021

Tactile suppression stems from sensation-specific sensorimotor predictions

The ability to sample sensory information with our hands is crucial for smooth and efficient interactions with the world. Despite this important role of touch, tactile sensations on a moving hand are perceived weaker than when presented on the same but stationary hand.1-3 This phenomenon of tactile suppression has been explained by predictive mechanisms, such as forward models, that estimate future sensory states of the body on the basis of the motor command and suppress the associated predicted sensory feedback.4 The origins of tactile suppression have sparked a lot of debate, with contemporary accounts claiming that suppression is independent of predictive mechanisms and is instead akin to unspecific gating.5 Here, we target this debate and provide evidence for sensation-specific tactile suppression due to sensorimotor predictions. Participants stroked with their finger over textured surfaces that caused predictable vibrotactile feedback signals on that finger. Shortly before touching the texture, we applied external vibrotactile probes on the moving finger that either matched or mismatched the frequency generated by the stroking movement. We found stronger suppression of the probes that matched the predicted sensory feedback. These results show that tactile suppression is not limited to unspecific gating but is specifically tuned to the predicted sensory states of a movement.

neuroscience↗

bioRxiv2021

Sensorimotor temporal recalibration: the contribution of motor-sensory and inter-sensory components

Adaptation to delays between actions and sensory feedback is important for efficiently interacting with our environment. Adaptation may rely on predictions of action-feedback pairing (motor-sensory component), or predictions of tactile-proprioceptive sensation from the action and sensory feedback of the action (inter-sensory component). Reliability of temporal information might differ across sensory feedback modalities (e.g. auditory or visual), influencing adaptation. Here, we investigated the role of motor-sensory and inter-sensory components on sensorimotor temporal recalibration for motor-auditory events (button press-tone) and motor-visual events (button press-Gabor patch). In the adaptation phase of the experiment, the motor action-feedback event pairs were presented with systematic temporal delays (0ms or 150ms). In the subsequent test phase, sensory feedback of the action were presented with variable delays. The participants were then asked whether this delay could be detected. To disentangle motor-sensory from inter-sensory component, we varied movements (active button press or passive depression of button) at adaptation and test. Our results suggest that motor-auditory recalibration is mainly driven by motor-sensory component, whereas motor-visual recalibration is mainly driven by inter-sensory component. Recalibration transferred from vision to audition, but not from audition to vision. These results indicate that motor-sensory and inter-sensory components of recalibration are weighted in a modality-dependent manner.

neuroscience↗

bioRxiv2019

HD-tDCS over mIPS causally modulates online reach correction

Brain lesion and stimulation studies have suggested posterior parietal cortex and the medial intraparietal sulcus in particular as a crucial hub for online movement error corrections. However, causal evidence for this is still sparse. Indeed, lesion studies are potentially confounded by compensatory reorganization mechanisms while brain stimulation studies have produced heterogeneous results when employing transcranial magnetic stimulation. Here we designed a new complementary paradigm using fMRI-guided high-definition transcranial direct current stimulation (HD-tDCS) of the left medial intraparietal sulcus (mIPS) together with regression-based mediation analysis to re-examine the causal role of mIPS in online reach corrections to jumping targets. We obtained two independent measures of stimulation-induced changes in brain activity by modeling current flow in the brain and through EEG recordings before and after HD-tDCS stimulation. Third, to quantify behavioral effects of HD-tDCS we computed movement curvature as a measure of online correction. We demonstrate that both of our measurements of brain activity were consistent with a polarity-specific modulation of the online correction for targets jumping to the contralateral side of the stimulation. Importantly, using a mediation analysis of the relationship between stimulation current and movement curvature suggests that the induced current modifies brain activity, which then leads to the observed behavioral changes. This unique combination of methods and analysis thus provides complementary evidence for the crucial role of the posterior parietal cortex in online error correction, while at the same time setting a new methodological standard with respect to the causal influence of transcranial direct current stimulation. New & NoteworthyTranscranial direct current stimulation (tDCS) is an interesting and potentially useful tool for asking causal scientific questions and design clinical treatments. With our unique combination of highly accurate fMRI guided stimulation, current forward modeling, EEG recordings before and after the stimulation and behavioral changes we could unravel the causal structure of tDCS. Our approach naturally deals with the variability of tDCS results, increasing its potential usefulness as a tool for research and clinical applications.

neuroscience↗

bioRxiv2019

Reaching around obstacles accounts for uncertainty in coordinate transformations

When reaching to a visual target, humans need to transform the spatial target representation into the coordinate system of their moving arm. It has been shown that increased uncertainty in such coordinate transformations, for instance when the head is rolled toward one shoulder, leads to higher movement variability and influence movement decisions. However, it is unknown whether the brain incorporates such added variability in planning and executing movements. We designed an obstacle avoidance task in which participants had to reach with or without visual feedback of the hand to a visual target while avoiding collisions with an obstacle. We varied coordinate transformation uncertainty by varying head roll (straight, 30{degrees} clockwise and 30{degrees} counterclockwise). In agreement with previous studies, we observed that the reaching variability increased when the head was tilted. Indeed, head roll did not influence the number of collisions during reaching compared to the head straight condition, but it did systematically change the obstacle avoidance behavior. Participants changed the preferred direction of passing the obstacle and increased the safety margins indicated by stronger movement curvature. These results suggest that the brain takes the added movement variability during head roll into account and compensates for it by adjusting the reaching trajectories.

neuroscience↗