Tactile Detection Research Articles

Vision automatically exerts online and offline influences on bimanual tactile spatial perception

Vision and touch interact in spatial perception. How vision exerts online influences on tactile spatial perception is well-appreciated, but far less is known regarding how recent visual experiences modulate tactile perception offline, particularly in a bimanual context. Here, we investigated how visual cues exert both online and offline biases in bimanual tactile spatial perception. In a series of experiments, participants performed a 4-alternative forced-choice tactile detection task in which they reported the perception of peri-threshold taps on the left hand, right hand, both hands, or no touch (LRBN). Participants initially performed the LRBN task in the absence of visual cues. Subsequently, participants performed the LRBN task in blocks comprising non-informative visual cues that were presented on the left and right hands. To explore the effect of distractor salience on the visuo-tactile spatial interactions, we varied the brightness of the visual cues such that visual stimuli associated with one hand were consistently brighter than visual stimuli associated with the other hand. We found that participants performed the tactile detection task in an unbiased manner prior to experiencing visual distractors. Concurrent visual cues biased tactile performance, despite an instruction to ignore vision, and these online effects tended to be larger with brighter distractors. Moreover, tactile performance was biased toward the side of the brighter visual cues even on trials when no visual cues were presented during the visuo-tactile block. Using a modeling framework based on signal detection theory, we compared a number of alternative models to recapitulate the behavioral results and to link the visual influences on touch to sensitivity and criterion reductions. Our collective results imply that recent visual experiences alter the sensitivity of tactile signal detection processes while concurrent visual cues induce more liberal perceptual decisions in the context of bimanual touch.

Layer 6 ensembles can selectively regulate the behavioral impact and layer-specific representation of sensory deviants.

Predictive models can enhance the salience of unanticipated input. Here, we tested a key potential node in neocortical model formation in this process, layer (L) 6, using behavioral, electrophysiological and imaging methods in mouse primary somatosensory neocortex. We found that deviant stimuli enhanced tactile detection and were encoded in L2/3 neural tuning. To test the contribution of L6, we applied weak optogenetic drive that changed which L6 neurons were sensory responsive, without affecting overall firing rates in L6 or L2/3. This stimulation selectively suppressed behavioral sensitivity to deviant stimuli, without impacting baseline performance. This stimulation also eliminated deviance encoding in L2/3 but did not impair basic stimulus responses across layers. In contrast, stronger L6 drive inhibited firing and suppressed overall sensory function. These findings indicate that, despite their sparse activity, specific ensembles of stimulus-driven L6 neurons are required to form neocortical predictions, and to realize their behavioral benefit.

Expansion of space for visuotactile interaction during visually induced self-motion.

Peripersonal space (PPS), which refers to space immediately around an individual's body, plays an important role in interacting with external objects and avoiding unsafe situations. Studies suggest that, during self-motion perception, PPS expands in the direction in which a person perceives himself/herself to be traveling. In the present study, we built on this by investigating, using visually induced self-motion (vection), how visual self-motion information modulates PPS representation. In our experiment, large-field visual motion was presented through a head-mounted display that caused observers to perceive themselves as moving forward in a tunnel (LF condition). To clarify the effects of self-motion information, we compared the findings for this condition with those of another condition, in which small-field visual motion was presented; here, only the central visual field represented motion, which caused the observers to perceive relatively little self-motion (SF condition). Two speeds were tested for both conditions: 1.5m/s and 6.0m/s. For measurement, we used a visuotactile-interaction task in which participants, while observing a visual probe object approaching from various distances, were instructed to press a response key as soon as they detected tactile stimuli delivered to their chest. We measured the distance at which the visual approaching probe object facilitated tactile detection (visual-facilitation effect); this was determined through comparisons with trials when no probe was presented. The results showed that the visual facilitation effects were observed for larger distance in the LF than SF conditions, irrespective of tested speeds. These results suggest that visual self-motion information can modulate PPS representation. This finding fits well with the view that PPS representation contributes to protecting the body from potential threats in the environment.

Quantitative sensory phenotyping in chronic neuropathic pain patients treated with unilateral L4-dorsal root ganglion stimulation

BackgroundIn a previous study, we reported that selective dorsal root ganglion stimulation (DRGSTIM) at DRG level L4 promoted a favorable outcome for complex regional pain syndrome (CRPS) patients along with DRGSTIM-related changes of inflammatory biomarkers in blood and saliva. The impact on somatosensation is largely unknown. Herein, we assessed the quantitative sensory profile to quantify L4-DRGSTIM effects in CRPS patients.MethodsTwelve refractory CRPS patients (4 female; 8 male; mean age 69 ± 9 years) received standardized quantitative sensory testing (QST) protocol at baseline and after 3 months of unilateral L4-DRGSTIM assessing nociceptive and non-nociceptive thermal and mechanical sensitivity of the knee affected by CRPS and the contralateral non-painful knee area.ResultsAt baseline, CRPS subjects showed significantly increased thresholds for warmth, tactile and vibration detection (WDT, MDT and VDT) and exaggerated pain summation (WUR). After 3 months of unilateral L4-DRGSTIM all pain parameters exhibited trends towards normalization of sensitivity accumulating to a significant overall normalization for pain sensitivity (effect size: 0.91, p < 0.01), while with the one exception of WDT all non-nociceptive QST parameters remained unchanged. Overall change of non-nociceptive detection was negligible (effect size: 0.25, p > 0.40). Notably, reduction of pain summation (WUR) correlated significantly with pain reduction after 3 months of L4-DRGSTIM.ConclusionsSelective L4-DRGSTIM lowered ongoing pain in CRPS patients and evoked significant normalization in the pain domain of the somatosensory profile. Thermoreception and mechanoreception remained unchanged. However, larger randomized, sham-controlled trials are highly warranted to shed more light on effects and mechanisms of dorsal root ganglion stimulation on quantitative sensory characteristics.The study protocol was registered at the 15.11.2016 on German Register for Clinical Trials (DRKS ID 00011267).https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00011267

Intact tactile detection yet biased tactile localization in a hand-centered frame of reference: Evidence from a dissociation

We examined the performance of an individual with subcortical damage, but an intact somatosensory thalamocortical pathway, to examine the functional architecture of tactile detection and tactile localization processes. Consistent with the intact somatosensory thalamocortical pathway, tactile detection on the contralesional hand was well within the normal range. Despite intact detection, the individual demonstrated substantial localization biases. Across all localization experiments, he consistently localized tactile stimuli to the left side in space relative to the long axis of his hand. This was observed when the contralesional hand was palm up, palm down, rotated 90° relative to the trunk, and when making verbal responses. Furthermore, control experiments demonstrated that this response pattern was unlikely a motor response error. These findings indicate that tactile localization on the body is influenced by proprioceptive information specifically in a hand-centered frame of reference. Furthermore, this also provides evidence that aspects of tactile localization are mediated by pathways outside of the primary somatosensory thalamocortical pathway.

Configuration optimization of bionic piezoelectric hair sensor for acoustic/tactile detection

Specialized sensory hairs are important biological sensors for arthropods to detect and recognize environmental conditions including acoustic, pressure and airflow signals. However, the present design methodology of such biomimic micro devices are mainly depending on shape mimicking, which greatly restricts their performance. In this paper, a novel genetic algorithm based optimization model for design of piezoelectric functional hair is developed for improving its acoustic pressure or tactile sensitivity. Furthermore, the sensing mechanism of axially polarized piezoelectric hair is explored and the main influencing factors on sensitivity including hair configuration and axial strain distribution are determined. Then, a series of optimized hair configurations are obtained in a specific frequency band from 1 Hz to 500 Hz, whose average sensitivity of 2.21 × 10−3 V Pa−1 is 10 times greater than that of the straight hair of 2.15 × 10−4 V Pa−1 with the same size. For tactile load detection, the output voltage of the optimized hair is about 1.5 times as much as that of the straight hair. The obtained hairs are similar with the spider’s trichobothria and tactile hair, which presents an explanation of biological hairs sensitive to dynamic and static loads.

Patterns of prey selection by the crab Cancer productus among three similar gastropod species (Nucella spp.)

Crabs are important predators known to influence the distribution, density, behaviour, and physical traits of their prey in marine ecosystems. However, the extent to which crabs, particularly generalists, differentiate or select among closely related prey species is less understood. Here, we examine prey preference in the red rock crab, Cancer productus Randall, 1840, between three closely related species of gastropod prey – Nucella ostrina (Gould, 1852), N. canaliculata (Duclos, 1832), and N. lamellosa (Gmelin, 1791). Crabs were presented with three individuals of each species distributed evenly in a 3 × 3 grid, and gastropods were ranked in the order that they were consumed. C. productus demonstrated a “preference” for N. lamellosa over both N. canaliculata (p = 0.019) and N. ostrina (p = 0.003), but were most likely to attack the first and then next gastropod they recognized, regardless of species, as they worked through the grid (p < 0.001). Crabs also appeared to have difficulty locating the last two gastropods, which always included at least one of N. ostrina and/or N. canaliculata. Given that N. lamellosa is the largest of the three species, and that crabs appeared to contact smaller gastropods without always recognizing them as prey, we suggest that crabs are more likely to recognize and attack the larger species of Nucella tactilely. As crabs attacked adjacent gastropods, regardless of species, and never rejected the smaller species, tactile detection of larger prey is therefore a more conservative explanation for prey selection between the three similar prey in this system.

Effects of aging on rapid grip force responses during bimanual manipulation of an active object.

Rapid grip force responses to unexpected pulling loads on the fingertips are deteriorated in older adults due to, in part, age-related declines in somatosensory function. Such reports are limited to one-hand conditions despite the higher frequency of using two hands together in daily living activities of older adults. Unexpected perturbations during bimanual movements elicit goal-oriented and cortically-meditated bilateral rapid motor responses. Since aging is associated with declined somatosensory and cognitive functions, we hypothesized that bilateral rapid motor responses differ between young and older adults, such that older adults exert stronger grip forces following perturbation and the unperturbed hand is more involved in stabilizing the object in older adults. We tested our hypothesis by comparing the rapid grip force responses of both hands in young and older adults. A total of 13 right-handed young individuals (24.2 ± 4.0years old, 5 men) and 13 right-handed older individuals (68.7 ± 7.1years old, 5 men) were recruited. Tactile detection threshold, fingertip friction, and the rapid grip force responses of both hands triggered by unpredicted pulling loads during grip-lift movements were assessed. Older adults had higher tactile detection thresholds and lower fingertip friction compared to young adults. Regardless of age, rapid motor responses were found in both the perturbed (right) hand and the indirectly perturbed (left) hand at 73ms and 135ms after the perturbation, respectively, while magnitudes of the responses depended on perturbation magnitudes. Higher values in maximum grip force and maximum grip force rate were found in older adults as compared to young adults. In older adults, the indirectly perturbed (left) hand was more involved in stabilizing the object as compared to young healthy adults. The current study suggests that age-related changes in the peripheral and central nervous systems contribute to the greater involvement of the indirectly perturbed hand in older adults.

High‐Resolution Monolithic Integrated Tribotronic InGaZnO Thin‐Film Transistor Array for Tactile Detection

AbstractTactile detection is a crucial technology in many fields, such as electronic skin, touch screen control, human prostheses, and screen fingerprint identification. Tribotronics has demonstrated active mechanosensation from external mechanical stimuli, which greatly enriches the sensing mechanisms of tactile detection. In this work, a monolithic integrated indium‐gallium‐zinc‐oxide (InGaZnO or IGZO) thin‐film transistor (TFT) array is developed for high‐resolution tactile detection. By using the conventional semiconductor fabrication processes, each IGZO TFT cell in the array shows uniform electrical performance. In addition, the drain–source current can be individually tuned by the electrostatic potential generated by the contact electrification between a movable gate and the gate dielectric. The monolithic integrated array displays a relatively high resolution of 12 pixels per inch and can realize a millimeter‐level tactile perception and motion tracking. This work presents a facile and viable strategy toward micro/nano‐scale tribotronics, which can realize high‐resolution and large‐scale tactile detection.

Design and Optimization of Fiber Optic Grating Pressure Sensing Array

Aiming at the haptic problem of robot hand pressure, this paper studies a fiber grating tactile sensor array. Using polydimethylsiloxane (PDMS) package, and the finite element simulation of the package body to obtain internal strain. Aiming at the strain field distribution when the robot hand is gripping, the design of preliminary sensor array and finite element analysis are carried out, and the improved particle swarm algorithm is used to further optimize the measurement points. It provides a theoretical basis for the subsequent construction of the measurement points of the FBG tactile sensor array detection system.

Bidirectional pharmacological perturbations of the noradrenergic system differentially affect tactile detection

The brain neuromodulatory systems heavily influence behavioral and cognitive processes. Previous work has shown that norepinephrine (NE), a classic neuromodulator mainly derived from the locus coeruleus (LC), enhances neuronal responses to sensory stimuli. However, the role of the LC-NE system in modulating perceptual task performance is not well understood. In addition, systemic perturbation of NE signaling has often been proposed to specifically target the LC in functional studies, yet the assumption that localized (specific) and systemic (nonspecific) perturbations of LC-NE have the same behavioral impact remains largely untested. In this study, we trained mice to perform a head-fixed, quantitative tactile detection task, and administered an α2 adrenergic receptor agonist or antagonist to pharmacologically down- or up-regulate LC-NE activity, respectively. We addressed the outstanding question of how bidirectional perturbations of LC-NE activity affect tactile detection, and tested whether localized and systemic drug treatments exert the same behavioral effects. We found that both localized and systemic suppression of LC-NE impaired tactile detection by reducing motivation. Surprisingly, while locally activating LC-NE enabled mice to perform in a near-optimal regime, systemic activation impaired behavior by promoting impulsivity. Our results demonstrate that localized silencing and activation of LC-NE differentially affect tactile detection, and that localized and systemic NE activation induce distinct behavioral changes.

Feeling better: Tactile verbs speed up tactile detection

Embodiment of action-related language into the motor system has been extensively documented. Yet the case of sensory words, especially referring to touch, remains overlooked. We investigated the influence of verbs denoting tactile sensations on tactile perception. In Experiment 1, participants detected tactile stimulations on their forearm, preceded by tactile or non-tactile verbs by one of three delays (170, 350, 500 ms) reflecting different word processing stages. Results revealed shorter reaction times to tactile stimulations following tactile than non-tactile verbs, irrespective of delay. To ensure that priming pertained to tactile, and not motor, verb properties, Experiment 2 compared the impact of tactile verbs to both action and non-tactile verbs, while stimulations were delivered on the index finger. No priming emerged following action verbs, therefore not supporting the motor-grounded interpretation. Facilitation by tactile verbs was however not observed, possibly owing to methodological changes. Experiment 3, identical to Experiment 2 except that stimulation was delivered to participants’ forearm, replicated the priming effect. Importantly, tactile stimulations were detected faster after tactile than after both non-tactile and action verbs, indicating that verbs’ tactile properties engaged resources shared with sensory perception. Our findings suggest that language conveying tactile information can activate somatosensory representations and subsequently promote tactile detection.

Sensory function in headache: a comparative study among patients with cluster headache, migraine, tension-type headache, and asymptomatic subjects.

Studies evaluating sensory function of the entire trigeminocervical region in patients with cluster headache (CH), migraine (MH), and tension-type headache (TH) are required. The purpose of the present study was to evaluate and compare sensory function in the trigeminocervical region in patients with CH, MH, and TH and healthy controls (HC). Quantitative sensory testing (QST), including pressure pain threshold (PPT), tactile detection threshold (TDT), prick detection threshold (PDT), and two-point detection threshold (2PDT), was evaluated in 139 patients with headache (CH = 16, MH = 52, TH = 71) and 30 HC. Test sites included bilaterally the first, second, and third divisions of trigeminal nerve (V1, V2, and V3), cervical spine, and thenar eminence. TH presented significantly lower PPT values compared with CH (p < 0.015), MH (p < 0.048), and HC (p < 0.009), while MH demonstrated significantly lower values than HC (p = 0.001-0.023). When analyzing TDT, CH in the symptomatic side presented significantly higher values in V1 compared with MH (p = 0.001), TH (p < 0.001), and HC (p < 0.001) and in V2 compared with TH (p = 0.035). No statistically significant differences were found for PDT (p > 0.005). With regard to 2PDT, CH-s presented significantly higher values in V1 with respect to HC (p = 0.016) but lower values in V2 compared with MH (p < 0.001) and TH (p = 0.003). The results of the present study indicate specific and different altered mechanical sensory thresholds in CH, MH, and TH patients compared with HC subjects.

Tactile detection response task: Metrics for assessing drivers’ cognitive workload

The Tactile Detection Response Task (TDRT) has been used to assess the cognitive workload of driver distraction with response time and miss rate as metrics of cognitive workload. However, it is not clear which metric is more sensitive and whether sensitivity is maintained for visual tasks. The objective of this study was to assess the sensitivity of the TDRT to changes in cognitive workload and to examine whether the sensitivity depends on task modality. A driving simulator study was conducted with 24 participants. The study included restaurant selection tasks with three presentation modalities (auditory, visual, and hybrid) and two difficulty levels (low and high). The high difficulty level was designed to be more cognitively demanding than the low difficulty level. Mixed-effects models were applied to examine the TDRT metrics and task difficulty level. The model controlled for age group, gender, and included a random effect for participants. The high difficulty level of the auditory tasks significantly increased the likelihood of missing a TDRT stimulus. No statistically significant differences were observed for visual and hybrid tasks. TDRT response time was not significantly associated with the difficulty level, regardless of task modality. In this study, the binary outcome TDRT miss was thus considered a more sensitive metric of cognitive workload than TDRT response time. TDRT response time can still be used to measure cognitive workload when tasks are relatively easy and the TDRT miss rate is close to zero. In addition, the sensitivity of the TDRT miss diminished for tasks that involved a visual component. Researchers who use TDRT to measure the cognitive workload associated with visual tasks should be aware of this limitation.

Unique Relationships Between Autistic Traits and Visual, Auditory, and Tactile Sensory Thresholds in Typically Developing Adults.

Autism spectrum disorder (ASD) refers to neurodevelopmental disorders characterized by symptoms such as social deficits and restricted interests and behavior. Several studies have investigated specific sensory processing in relation to ASD traits. However, findings appear to be inconsistent and inconclusive because of variation in ASD traits among participants and differences in the tasks adopted. In this study, we investigated relationships between sensory thresholds in visual, auditory, and tactile modalities and various ASD traits to account for individual variability of traits in typically developing adults using the same experimental tasks. We estimated detection and discrimination thresholds for brightness, sound pressure, and vibrotactile stimulus strength. We also estimated the degree of ASD traits in each participant with a questionnaire. We found that higher tactile detection and visual discrimination thresholds were related to ASD traits in difficulty of communication. A lower tactile discrimination threshold and higher visual detection threshold was also related to the ASD trait of strong focus of attention. These findings suggest the existence of unique relationships between particular low-level sensory processing and specific ASD traits, indicating that irregularities in sensory processing may underlie variation in ASD traits.

A thermally flexible and multi-site tactile sensor for remote 3D dynamic sensing imaging

A flexible, multi-site tactile and thermal sensor (MTTS) based on polyvinylidene fluoride (resolution 50 50) is reported. It can be used to implement spatial mapping caused by tactile and thermal events and record the two-dimensional motion trajectory of a tracked target object. The output voltage and current signal are recorded as a mapping by sensing the external pressure and thermal radiation stimulus, and the response distribution is dynamically observed on the three-dimensional interface. Through the mapping relationship between the established piezoelectric and pyroelectric signals, the piezoelectric component and the pyroelectric component are effectively extracted from the composite signals. The MTTS has a good sensitivity for tactile and thermal detection, and the electrodes have good synchronism. In addition, the signal interference is less than 9.5% and decreases as the pressure decreases after the distance between adjacent sites exceeds 200 mm. The integration of MTTS and signal processing units has potential applications in human-machine interaction systems, health status detection and smart assistive devices.

The sense of body-ownership gates cross-modal improvement of tactile extinction in brain-damaged patients

When body ownership is impaired after brain-damage, the capacity to discriminate between one's own and others' body-parts is lost. Delusional body-ownership has been recently described in patients who misidentify someone else's limb as their own (pathological embodiment) whenever it is positioned in a body congruent position. This delusion can be frequently associated with somatosensory and attentional deficits. Here, we leveraged the phenomenon of tactile extinction, as this clinical sign can be substantially ameliorated when contralesional touches are combined with proximal visual stimulation. Is body ownership a necessary prerequisite to modulate cross-modal processing and thus reducing tactile extinction? Fourteen patients with tactile extinction (TE+) took part in the study: eight of them with pathological embodiment (E+, experimental group) and six of them without pathological embodiment (E-, control group). In two different paradigms, differing for the nature of visuo-tactile stimuli, bilateral tactile stimulation of the patients' hands was combined with visual stimuli occurring on A) their own contralesional (affected) hand, B) the examiner's hand (embodied in E+), or C) a neutral object. In both groups, visual stimuli proximal to the own hand significantly improved contralesional tactile detection, while visual stimuli occurring on the neutral object did not. Crucially, only in E+TE+ patients did visual stimuli on the examiner's (embodied) hand improve contralesional tactile detection. This finding shows that cross-modal visuo-tactile integration is conditional to body-ownership, so that it ameliorates tactile extinction when visual stimuli occur on what is believed to be one's own body. From a clinical point of view, this study suggests that the effectiveness of cross-modal rehabilitative intervention can benefit from a careful evaluation of the patients' sense of body-ownership, so often impaired after brain-damage.

Sympatric sister species with divergent morphological features of psammophilic catfishes of the south-eastern Brazilian genus Microcambeva (Siluriformes: Trichomycteridae)

An undescribed species of Microcambeva, a genus of small psammophilic catfishes from the Atlantic Forest of south-eastern Brazil, was found together the congener Microcambeva ribeirae inhabiting the same sand stretch of a stream, in the Rio Ribeira do Iguape basin. The new species and its sympatric congener exhibit highly divergent morphological features, but a multigene phylogeny support them as sister taxa. The new species, M. filamentosa sp. nov., is readily distinguished from all other congeners by the presence of long barbels, long filamentous first pectoral-fin ray and a hypertrophied predorsal adipose fold. Microcambeva filamentosa and M. ribeirae share two unique apomorphic features: a single supraorbital pore s6 situated on the centre of the dorsal surface of the head and a deep concavity between the dorsal process of the opercle and the opercular odontode patch, conditions that are independently acquired in other psammophilic trichomycterids. A comparative context, involving other trichomycterid lineages exhibiting similar morphological adaptations, highly suggests that morphological differences between M. filamentosa and M. ribeirae are related to different strategies to exploit their habitat. In M. ribeirae, the short and thickened first pectoral-fin ray is interpreted as an adaptation to the fish posing propped on the substratum while visually detecting potential preys, what is reinforced by the unique possession in this taxon of a relatively large eye positioned on the top of the head. On the other hand, the relatively small eye and long barbels of M. filamentosa highly suggest the use of a predominantly chemosensory and tactile detection of food, indicating possible nocturnal habits.

Sharpened self-other distinction in attention deficit hyperactivity disorder

IntroductionDifferentiation between self-produced tactile stimuli and touch by others is necessary for social interactions and for a coherent concept of “self”. In attention-deficit-hyperactivity-disorder (ADHD), tactile hypersensitivity and social cognition problems are part of the symptomatology, but pathophysiological mechanisms are largely unknown. Differentiation of self- and non-self- generated sensations might be key to understand and develop novel strategies for managing hypersensitivity. Here, we compared the neural signatures of affective self- and other-touch between adults with ADHD and neurotypical controls (NC). MethodsTwenty-eight adult ADHD participants and 30 age- and gender-matched NC performed a self-other-touch-task during functional magnetic resonance imaging: they stroked their own arm, an object, or were stroked by the experimenter. In addition, tactile detection thresholds and rubber hand illusion (RHI) were measured. ResultsADHD participants had more autistic traits than NC and reported to engage less in interpersonal touch. They also reported to be more sensitive to tactile stimuli. Compared to NC, ADHD participants showed enhanced responses to both the self- and other-touch conditions: stronger deactivation during self-touch in the anterior and posterior insula, and increased activation during other-touch in primary somatosensory cortex. ADHD participants had intact tactile detection thresholds, but were less susceptible to the RHI. ConclusionsUnaltered detection thresholds suggest that peripheral processing is intact, and that hypersensitivity might be driven by central mechanisms. This has clinical implications for managing somatosensory hypersensitivity in ADHD. The more pronounced differentiation between self- and other-touch might indicate a clearer self-other-distinction. This is of interest regarding body ownership perception in both NC and ADHD, and possibly other psychiatric conditions with altered self-experiences, like schizophrenia. A sharper boundary of the own body might relate to deficits in social cognition and tactile hypersensitivity.

Allocation of Driver Attention for Varying In-Vehicle System Modalities.

This paper examines drivers' allocation of attention using response time to a tactile detection response task (TDRT) while interacting with an in-vehicle information system (IVIS) over time. Longer TDRT response time is associated with higher cognitive workload. However, it is not clear what role is assumed by the human and system in response to varying in-vehicle environments over time. A driving simulator study with 24 participants was conducted with a restaurant selection task of two difficulty levels (easy and hard) presented in three modalities (audio only, visual only, hybrid). A linear mixed-effects model was applied to identify factors that affect TDRT response time. A nonparametric time-series model was also used to explore the visual attention allocation under the hybrid mode over time. The visual-only mode significantly increased participants' response time compared with the audio-only mode. Females took longer to respond to the TDRT when engaged with an IVIS. The study showed that participants tend to use the visual component more toward the end of the easy tasks, whereas the visual mode was used more at the beginning of the harder tasks. The visual-only mode of the IVIS increased drivers' cognitive workload when compared with the auditory-only mode. Drivers showed different visual attention allocation during the easy and hard restaurant selection tasks in the hybrid mode. The findings can help guide the design of automotive user interfaces and help manage cognitive workload.