Haptic Conditions Research Articles

Virtual reality-based simulation improves rotator cuff repair skill: a randomized transfer validity study.

Although virtual reality (VR) simulators have demonstrated their efficiency for basic technical skill training of healthcare professionals, validation for more complex and sequential procedures, especially in arthroscopic surgery, is still warranted. We hypothesized that the VR-based training simulation improves arthroscopic cuff repair skills when transferred to realistic visual and haptic conditions. VR-based training simulation improves arthroscopic cuff repair skills when transferred to realistic visual and haptic conditions. This study is prospective, multicentric and randomized. Thirty orthopedic surgery residents were enrolled in the study and randomized in two groups: VR training (VR+) and no VR training (VR-). Only the VR + group underwent a monthly VR-based training program for rotator cuff repair. The 1 -h VR training sessions were standardized and supervised by the same instructor. After six months, all participants performed a double-row arthroscopic rotator cuff repair procedure on a benchtop shoulder model providing realistic visual and haptic conditions with implants. Two independent surgeons with expertise in shoulder repair and blinded to the randomization rated the participants' performance using the Arthroscopic Surgical Skill Evaluation Tool (ASSET). Demographic characteristics and surgical experience were comparable between the two groups. The ASSET global rating score was higher in the VR + group than in the VR- group (34.4 ± 3.1 and 30.5 ± 5.7, respectively; p = 0.046) and the VR+ group performed the procedure faster than the VR- group (27.3 ± 3.6 vs. 31.7 ± 0.4 minutes, respectively; p = 0,003). This study demonstrated that a monthly VR-based program for 6 months was better than standard peer training alone for mastering a complex and sequential rotator cuff repair when using the validated ASSET Score. Overall, nonspecific arthroscopic skills were also higher in the VR + group. II, therapeutic study.

Gaze and hand behaviors during haptic abilities testing-An update to multimedia learning theory.

The Cognitive Theory of Multimedia Learning (CTML) suggests humans learn through visual and auditory sensory channels. Haptics represent a third channel within CTML and a missing component for experiential learning. The objective was to measure visual and haptic behaviors during spatial tasks. The haptic abilities test (HAT) quantifies results in several realms, accuracy, time, and strategy. The HAT was completed under three sensory conditions using sight (S), haptics (H), and sight with haptics (SH). Subjects (n = 22, 13 females (F), 20-28 years) completed the MRT (10.6 ± 5.0, mean ± SD) and were classified as high or low spatial abilities scores with respect to mean MRT: high spatial abilities (HSA) (n = 12, 6F, MRT = 13.7 ± 3.0), and low spatial ability (LSA) groups (n = 10, 7F, MRT = 5.6 ± 2.0). Video recordings gaze and hand behaviors were compared between HSA and LSA groups across HAT conditions. The HSA group spent less time fixating on mirrored objects, an erroneous answer option, of HAT compared to the LSA group (11.0 ± 4.7 vs. 17.8 ± 7.3 s, p = 0.020) in S conditions. In haptic conditions, HSA utilized a hand-object interaction strategy characterized as palpation, significantly less than the LSA group (23.2 ± 16.0 vs. 43.1 ± 21.5 percent, p = 0.022). Before this study, it was unclear whether haptic sensory inputs appended to the mental schema models of the CTML. These data suggest that if spatial abilities are challenged, LSA persons both benefit and utilize strategies beyond the classic CTML framework by using their hands as a third input channel. This data suggest haptic behaviors offer a third type of sensory memory resulting in improved cognitive performance.

Development and Validation of a Tool for VBOI (Virtual Body Ownership Illusion) Level Assessment

Virtual Body Ownership Illusion (Virtual BOI) refers to the perceptual, cognitive, and behavioral changes that occur due to the illusion that a virtual body is one’s own actual body. Recent research has focused on inducing Virtual Body Ownership Illusion (Virtual BOI) using various physical conditions of VR environments such as haptic feedback and 360-degree immersion, among others. The level of Virtual BOI has been recognized as an important factor in VR-based clinical therapy programs where patient immersion is crucial. However, a common issue is the lack of standardized evaluation tools for Virtual BOI, with most experiments relying on ad hoc tools based on experimental conditions or lacking consideration for the physical design elements of VR. This measurement tool was designed to consider the characteristics of recent VR devices, such as haptics and hand tracking, in the design of experiments and questionnaires. The tool is composed of sub-attributes related to VR technology, including Embodiment, Presence, Visuo-tactile, Visuo-proprioceptive, and Visuo-Motor. Based on a review of the existing literature, we hypothesized that the Virtual BOI scores would vary depending on manipulation methods, viewpoints, and haptic conditions. An experiment was conducted with 39 participants, who performed the same task under four different conditions using a virtual hand. Virtual BOI scores were assessed using the evaluation tool developed for this study. The questionnaire underwent CFA, and three items with factor loadings below 0.5 were removed, resulting in a total of 14 items. Each subscale demonstrated high reliability, with Cronbach’s alpha values greater than 0.60. When developing experiments, clinical programs, or VR content related to Virtual BOI, the evaluation tool presented in this study can be used to assess the level of Virtual BOI. Additionally, by considering technological elements such as haptics and hand tracking, VR environments can be designed to enhance the level of Virtual BOI.

Scaling up = scaling down? Children’s spatial scaling in different perceptual modalities and scaling directions

The present study examined whether scaling direction and perceptual modality affect children’s spatial scaling. Children aged 6–8 years (N = 201) were assigned to a visual, visuo-haptic, and haptic condition in which they were presented with colourful, embossed graphics. In the haptic condition, they were asked to wear a blindfold during the test trials. Across several trials, children were asked to learn about the position of a target in a map and to localize a disc at the same location in a referent space. Scaling factor was manipulated systematically, so that children had to either scale up or scale down spatial information. Their absolute deviations from the correct target location, reversal and signed errors, and response times served as dependent variables. Results revealed higher absolute deviations and response times for the haptic modality as opposed to the visual modality. Children’s signed errors, however, showed similar response strategies across the perceptual conditions. Therefore, it seems that a functional equivalence between vision and touch seems to emerge slowly across development for spatial scaling. With respect to scaling directions, findings showed that absolute deviations were affected by scaling factors, with symmetric increases in scaling up and scaling down in the haptic condition. Conversely, children showed an unbalanced pattern in the visual conditions, with higher accuracy in scaling down as opposed to scaling up. Overall, our findings suggest that visibility seems to factor into children’s scaling process.

Shaping Human Movement via Bimanually-Dependent Haptic Force Feedback.

Haptic feedback can enhance training and performance of human operators; however, the design of haptic feedback for bimanual coordination in robot-assisted tasks (e.g., control of surgical robots) remains an open problem. In this study, we present four bimanually-dependent haptic force feedback conditions aimed at shaping bimanual movement according to geometric characteristics: the number of targets, direction, and symmetry. Haptic conditions include a virtual spring, damper, combination spring-damper, and dual springs placed between the hands. We evaluate the effects of these haptic conditions on trajectory shape, smoothness, and speed. We hypothesized that for subjects who perform worse with no haptic feedback (1) a spring will improve the shape of parallel trajectories, (2) a damper will improve the shape of point symmetric trajectories, (3) dual springs will improve the shape of trajectories with one target, and (4) a damper will improve smoothness for all trajectories. Hypotheses (1) and (2) were statistically supported at the p < 0.001 level, but hypotheses (3) and (4) were not supported. Moreover, bimanually-dependent haptic feedback tended to improve shape accuracy for movements that subjects performed worse on under no haptic condition. Thus, bimanual haptic feedback based on geometric trajectory characteristics shows promise to improve performance in robot-assisted motor tasks.

Assessing the representational structure of softness activated by words

Softness is an important material property that can be judged directly, by interacting with an object, but also indirectly, by simply looking at an image of a material. The latter is likely possible by filling in relevant multisensory information from prior experiences with soft materials. Such experiences are thought to lead to associations that make up our representations about perceptual softness. Here, we investigate the structure of this representational space when activated by words, and compare it to haptic and visual perceptual spaces that we obtained in earlier work. To this end, we performed an online study where people rated different sensory aspects of soft materials, presented as written names. We compared the results with the previous studies where identical ratings were made on the basis of visual and haptic information. Correlation and Procrustes analyses show that, overall, the representational spaces of verbally presented materials were similar to those obtained from haptic and visual experiments. However, a classifier analysis showed that verbal representations could better be predicted from those obtained from visual than from haptic experiments. In a second study we rule out that these larger discrepancies in representations between verbal and haptic conditions could be due to difficulties in material identification in haptic experiments. We discuss the results with respect to the recent idea that at perceived softness is a multidimensional construct.

Learning Statics through Physical Manipulative Tools and Visuohaptic Simulations: The Effect of Visual and Haptic Feedback

In this study, we: (a) compared the differences in the learning of friction concepts between a physical manipulative tool (PMT) and a visuohaptic simulation (VHS) in four different configurations (visually enhanced feedback on/off, force feedback on/off), and (b) analyzed the influence of the visual and haptic feedback for learning the concept of friction. Specifically, this study explored the role of an object’s size in friction. In a three-stage experiment (i.e., pre-test, experimentation, and post-test), 206 undergraduate students compared the friction force, speed, acceleration, and traveled distance between two cubes with the same weight but different sizes pushed on a smooth surface. Our results suggest that (a) VHS was an effective tool for promoting the learning of friction concepts actively, (b) learners in the VHS condition outperformed the learners in the PMT condition (PMT &lt; VHS), (c) the easy identification of the forces by enhanced visual cues promoted the acquisition of scientific knowledge, (d) the haptic feedback promoted a grounded experience for learning about friction, and (e) learners in the Sequenced (H→H + V) condition had more learning benefits than the Simultaneous (H + V), Visual, and Haptic conditions. Students in the Sequenced (H→H + V) condition took advantage of the affordances of the virtual and physical manipulatives. The implication for teaching and learning is that the virtual and physical affordances of the learning tools and the students’ prior knowledge must be considered in the design of the VHS to enhance learning. For the education research, the study implied that body actions positively impacted the learning experience.

Surgical Simulation of Posterior Sagittal Anorectoplasty for Rectovestibular Fistula: Low-Cost High-Fidelity Animal-Tissue Model

PurposeTo provide a high-fidelity, animal tissue-based model for the advanced surgical simulation of a Posterior Sagittal Anorectoplasty (PSARP) for rectovestibular fistula in anorectal malformation (ARM). Materials and methodsA chicken cadaver was used to assess the feasibility of simulating a PSARP for rectovestibular fistula in ARM. No modification was required to implement the surgical simulation. ResultsA detailed description of the high-fidelity surgical simulation model is provided. The PSARP can be simulated while providing realistic anatomy (e.g. common wall between rectovestibular fistula and vagina), adequate rectal size, location and placement of the rectovestibular fistula, and proximity to the vagina. Haptic conditions of the tissue resemble human tissue and operative conditions as well. DiscussionConcerning the decreased exposure of index cases of pediatric surgical trainees and pediatric surgeons in practice, simulation-based training can provide means to acquire or maintain the necessary skills to perform complex surgical procedures [1–5]Surgical simulation models for ARM are limited. Few low-cost trainers are available with predominant artificial and mostly unrealistic tissue [6–8] Animal models have the advantage of realistic multilayer tissue haptic feedback [6]. ConclusionWe provide a low-cost, high-fidelity model for correcting a rectovestibular fistula in a child with ARM, a complex operative procedure with low incidence but high-stake outcomes. The described tissue model utilizing the chicken cloaca anatomy provides a high-fidelity model for operative correction of rectovestibular ARM. For simulation purposes in the treatment of ARM, this model appears to be promising in terms of providing realistic pathology and haptic feedback in pediatric dimensions. Level of evidenceV.

Youth with Cerebral Palsy Display Abnormal Somatosensory Cortical Activity During a Haptic Exploration Task

There are numerous clinical reports that youth with cerebral palsy (CP) have proprioceptive, stereognosis and tactile discrimination deficits. The growing consensus is that the altered perceptions in this population are attributable to aberrant somatosensory cortical activity seen during stimulus processing. It has been inferred from these results that youth with CP likely do not adequately process ongoing sensory feedback during motor performance. However, this conjecture has not been tested. Herein, we address this knowledge gap using magnetoencephalographic (MEG) brain imaging by applying electrical stimulation to the median nerve of youth with CP (N = 15, Age = 15.8 ± 0.83 yrs, Males = 12, MACS levels I-III) and neurotypical (NT) controls (N = 18, Age = 14.1 ± 2.4 yrs, Males = 9) while at rest (i.e., passive) and during a haptic exploration task. The results illustrated that the somatosensory cortical activity was reduced in the group with CP compared to controls during the passive and haptic conditions. Furthermore, the strength of the somatosensory cortical responses during the passive condition were positively associated with the strength of somatosensory cortical responses during the haptic condition (r = 0.75, P = 0.004). This indicates that the aberrant somatosensory cortical responses seen in youth with CP during rest are a good predictor of the extent of somatosensory cortical dysfunction during the performance of motor actions. These data provide novel evidence that aberrations in somatosensory cortical function in youth with CP likely contribute to the difficulties in sensorimotor integration and the ability to effectively plan and execute motor actions.

Improving Teleoperation Through Human-Aware Haptic Feedback: A Distinguishable and Interpretable Physical Interaction Based on the Contact State

Teleoperation with haptic feedback is especially useful for contact-rich manipulation. Humans can easily perceive physical interaction events and effects of hands-on manipulation. However, current measurement-based haptic rendering methods with distorting and confusing transmission limit teleoperation performance. The major problem is a mismatch between low-level modulated sensor signals and human-aware haptic stimuli. We explore a human-aware haptic feedback pipeline that renders a distinguishable and interpretable physical interaction based on the contact states. Manipulation tasks are modeled as time-series sequences of four contact states: 1) <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">noncontact</i> , 2) <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">contact</i> , 3) <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">stick</i> , and 4) <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">slip</i> . The temporal convolutional network model fuses force/torque sensor and velocity signals in real time to identify the four contact states with a 91.3% accuracy. Meanwhile, state-dependent haptic feedback, which combines transient and continuous feedback, brings more cues for physical interaction events and effects, corresponding to human fast- and slow-adapting receptors. We formulate a two-peak waveform for transient feedback based on a second-order superimposed exponentially decaying sinusoid model and adopt the orthogonal decomposition filter method for “inequable” continuous feedback. We demonstrate the effectiveness of our method through contact state and teleoperation experiments under different haptic conditions. The results indicate that the proposed method helps the operator to perceive and understand physical interaction and significantly improves teleoperation performance.

Learning Clinical Skills Using Haptic vs. Phantom Head Dental Chair Simulators in Removal of Artificial Caries: Cluster-Randomized Trials with Two Cohorts' Cavity Preparation.

Dental task trainer simulators using haptics (virtual touch) offers a cost-effective method of teaching certain clinical skills. The purpose of this study is to evaluate students' performance in removing artificial caries after training with either a haptic dental chair simulator with virtual reality or a traditional dental chair simulator with a mannequin head. Cluster Randomized Controlled Trials in two cohorts, both Year 1 dental students. Students taught using traditional dental chair simulators were compared with students taught using haptic-based simulators on their ability to cut a cavity in a plastic tooth following training. Across both cohorts, there was no difference in the quality of cavity cut, though students' technique differed across the two simulator groups in some respects. No difference was seen across both cohorts in the quality of cavity cut for a simple preparation, though students in the haptic condition performed less well in the more demanding task. Moreover, students in the haptic group were also less likely to be perceived to be 'holding the instrument appropriately'. These findings suggest further investigation is needed into the differences in handling of instruments and level of clinical task difficulty between the simulators.

Adults' spatial scaling from memory: Comparing the visual and haptic domain.

The current study compared adults' spatial scaling from memory in the visual and haptic domain. Adults (N = 32, ages 19-27 years) were presented with a spatial-scaling task in a visual condition as well as a haptic condition (in which participants were blindfolded throughout the experimental session). In both conditions, they were presented with an embossed graphic including a target (i.e., a map). Then, they were asked to encode this map and to place a disc at the same spot on an empty referent space from memory. Maps had three different sizes whereas the referent space had a constant size, resulting in three different scaling factors (1:1, 1:2, 1:4). Participants' response times and absolute errors were measured. Order of perceptual condition was counterbalanced across participants. Analyses indicated that response times and absolute errors increased linearly with higher scaling factors in the visual as well as the haptic perceptual condition. In analogy to mental imagery research, these results suggest the usage of mental transformation strategies for spatial scaling.

Evaluation of Spatial Directional Guidance Using Cheek Haptic Stimulation in a Virtual Environment

Spatial cues play an important role in navigating people in both physical and virtual spaces. In spatial navigation, visual information with additional cues, such as haptic cues, enables effective guidance. Most haptic devices are applied to various body parts to make mechanical stimuli, while few devices stimulate a head despite the excellent sensitivity. This article presents Virtual Whiskers, a spatial directional guidance technique by cheek haptic stimulation using tiny robot arms attached to a Head-Mounted Display (HMD). The tip of the robotic arm has photo reflective sensors to detect the distance between the tip and the cheek surface. Using the robot arms, we stimulate a point on the cheek obtained by calculating an intersection between the cheek surface and the target direction. In the directional guidance experiment, we investigated how accurately participants identify the target direction provided by our guidance method. We evaluated an error between the actual target direction and the participant's pointed direction. The experimental result shows that our method achieves the average absolute directional error of 2.54° in the azimuthal plane and 6.54° in the elevation plane. We also conducted a spatial guidance experiment to evaluate task performance in a target search task. We compared the condition of visual information, visual and audio information, and visual information and cheek haptics for task completion time, System Usability Scale (SUS) score, NASA-TLX score. The averages of task completion time were M = 6.39 s, SD = 3.34 s, and M = 5.62 s, SD = 3.12 s, and M = 4.35 s, SD = 2.26 s, in visual-only condition, visual+audio condition, and visual+haptic condition, respectively. In terms of the SUS score, visual condition, visual+audio condition, and visual+haptic condition achieved M = 55.83, SD = 20.40, and M = 47.78, SD = 20.09, and M = 80.42, SD = 10.99, respectively. As for NASA-TLX score, visual condition, visual+audio condition, and visual+haptic condition resulted in M = 75.81, SD = 16.89, and M = 67.57, SD = 14.96, and M = 38.83, SD = 18.52, respectively. Statistical tests revealed significant differences in task completion time, SUS score, and NASA-TLX score between the visual and the visual+haptic condition and the visual+audio and the visual+haptic condition.

Understanding the Role of Perceptual Haptic Conditions on Design Decision

AbstractThe haptic propositions derived from the textile prototypes often allow for more than one interpretation. It impacts the decision on design alternatives during the phase of design evaluation and validation. The present study aims to conquer this challenge with a haptic design case study of automotive upholstery fabric. It links experimental psychophysics with design decision-making. The study results show that visual cues influence haptic detection accuracy and constancy to choose a final design option.

The Role of Spatial and Modality Cues on Visual and Haptic Memory.

This study investigates the ability to remember a sequence of stimuli in two basic conditions: haptic and visual. Participants rely on a combination of modal and/or spatial information to perform a memory task. For this purpose, an experimental setup was developed based on the "Simon Says" memory game. Individuals receive a series of sensory stimuli and need to remember the sequence and repeat it. The stimuli in visual conditions are colored or white lights, and the stimuli in haptic conditions are vibration, hot, cold, and skin stretch. Results demonstrate that participants retained longer sequences in spatial conditions compared to the modal conditions. It is also demonstrated that participants performed better in visual conditions compared to haptic conditions. Participants were able to retain more complex spatial patterns and remember them faster in visual conditions compared to haptic conditions. A spatial difficulty ranking system was developed, indicating how easily each spatial pattern can be retained visually and haptically.

Differences in adults' spatial scaling based on visual or haptic information.

The present study examined differences in adults’ spatial-scaling abilities across three perceptual conditions: (1) visual, (2) haptic, and (3) visual and haptic. Participants were instructed to encode the position of a convex target presented in a simple map without a time limit. Immediately after encoding the map, participants were presented with a referent space and asked to place a disc at the same location from memory. All spaces were designed as tactile graphics. Positions of targets varied along the horizontal dimension. The referent space was constant in size while sizes of maps were systematically varied, resulting in three scaling factor conditions: 1:4, 1:2, 1:1. Sixty adults participated in the study (M = 21.18; SD = 1.05). One-third of them was blindfolded throughout the entire experiment (haptic condition). The second group of participants was allowed to see the graphics (visual condition); the third group were instructed to see and touch the graphics (bimodal condition). An analysis of participants’ absolute errors showed that participants produced larger errors in the haptic condition as opposed to the visual and bimodal conditions. There was also a significant interaction effect between scaling factor and perceptual condition. In the visual and bimodal conditions, results showed a linear increase in errors with higher scaling factors (which may suggest that adults adopted mental transformation strategies during the spatial scaling process), whereas, in the haptic condition, this relation was quadratic. Findings imply that adults’ spatial-scaling performance decreases when visual information is not available.

Visual-haptic integration, action and embodiment in virtual reality.

The current generation of virtual reality (VR) technologies has improved substantially from legacy systems, particularly in the resolution and latency of their visual display. The presentation of haptic cues remains challenging, however, because haptic systems do not generalise well over the range of stimuli (both tactile and proprioceptive) normally present when interacting with objects in the world. This study investigated whether veridical tactile and proprioceptive cues lead to more efficient interaction with a virtual environment. Interaction in the world results in spatial and temporal correlation of tactile, proprioceptive and visual cues. When cues in VR are similarly correlated, observers experience a sense of embodiment and agency of their avatars. We investigated whether sensorimotor performance was mediated by embodiment of the avatar hands. Participants performed a Fitts' tapping task in different conditions (VR with no haptics, active haptics, passive haptics, and on a real touchscreen). The active-haptic condition provided abstract tactile cues and the passive haptic condition provided veridical tactile and proprioceptive cues. An additional (hybrid haptics) condition simulated an ideal passive haptic system. Movement efficiency (throughput) and embodiment were higher for the passive than for the active and no-haptics conditions. However, components of embodiment (perceived agency and ownership) did not predict unique variance in throughput. Improved sensorimotor performance and ratings of presence and realism support the use of passive haptics in VR environments where objects are in known and stable locations, regardless of whether performance was mediated by the sense of embodiment.

The look and feel of soft are similar across different softness dimensions.

The softness of objects can be perceived through several senses. For instance, to judge the softness of a cat's fur, we do not only look at it, we often also run our fingers through its coat. Recently, we have shown that haptically perceived softness covaries with the compliance, viscosity, granularity, and furriness of materials (Dovencioglu, Üstün, Doerschner, & Drewing, 2020). However, it is unknown whether vision can provide similar information about the various aspects of perceived softness. Here, we investigated this question in an experiment with three conditions: in the haptic condition, blindfolded participants explored materials with their hands, in the static visual condition participants were presented with close-up photographs of the same materials, and in the dynamic visual condition participants watched videos of the hand-material interactions that were recorded in the haptic condition. After haptically or visually exploring the materials, participants rated them on various attributes. Our results show a high overall perceptual correspondence among the three experimental conditions. With a few exceptions, this correspondence tended to be strongest between haptic and dynamic visual conditions. These results are discussed with respect to information potentially available through the senses, or through prior experience, when judging the softness of materials.

Shape congruence modulates visuo-haptic interactions during binocular rivalry

When two dissimilar images are presented to the corresponding retinal positions of the two eyes, perception alternates between the two images (Blake & Logothetis, 2002). Dubbed binocular rivalry (BR), this paradigm provides a window into inferential visual processing. Recent experiments using multisensory stimuli found that tactile information boosts the dominance of the congruent visual stimulus (Lunghi et al., 2010; Suzuki et al., 2019). The present study examines whether dynamic haptic exploration of 3D shape objects boosts the perception of congruent visual shape stimuli during BR. 3D spiky and round shapes were created with a parametric shape model (Gielis, 2003). The coordinates for the neutral shape were acquired through linear interpolation of round and spiky shape coordinates (Kwak et al., VSS 2018). Visual and haptic stimuli were each created by 3D rendering and 3D printing the shape models. Participants viewed a pair of rotating round and spiky shapes as rival targets while exploring haptic objects with their left hand. They used their right hand to track perceptual dominance via computer key press. There were four haptic conditions - three exploring round, spiky, and neutral shape objects and one with no haptic stimulation (visual-only). Visual dominance durations for each condition were normalized with the mean duration of visual-only trials to account for individual differences. Analyses showed significant differences in the normalized dominance durations of both round and spiky visual targets when exploring haptic stimuli of different shapes. Specifically, haptic exploration of an object was associated with increased dominance of the corresponding visual target for both round and spiky shape during BR. With these results based on stimuli parametrically modulated in a single shape dimension of curvature, we suggest that shape congruence between visual and haptic modalities boosts the dominance of the corresponding visual target.

Visual and Haptic Perception of Affordances of Feelies

Most human-made objects are designed with a particular function and a particular user in mind. This means that most objects have well-defined affordances. An important question that remains unanswered concerns the perception of affordances of objects that were not created for a specific purpose. Investigating perception of affordances of such objects would provide insight into how affordances are perceived via exploratory activity. In addition, the comparison of perception of affordances of ambiguous objects across vision and haptics would offer a strong test of the lawfulness of information about affordances (i.e., the invariance of such information over transformation). The use of - objects created by Gibson (1962) with no obvious function and unlike any common object - could shed light on these processes. The present study showed that when observers reported potential uses for feelies, modality significantly influenced what kind of affordances were perceived. Specifically, visual exploration reulted in more noun labels (e.g. toy) and haptic exploration resulted in more verb labels (i.e. throw). These results suggested that overlapping, but distinct classes of action possibilities are readily perceivable using vision and haptics. Semantic network analyses revealed that visual exploration resulted in object-oriented responses focused on object identification, whereas haptic exploration resulted in action-oriented responses. Cluster analyses confirmed these results. Affordance labels produced in the visual condition were more consistent, used fewer descriptors, were less diverse, but were more novel than those in the haptic condition. How the unique shape of feelies influences affordance judgments is currently being investigated, but the multiple convex and concave surface regions could be critical in providing information about affordances, with different patterns of surface curvature specifying different affordances.