Training haptic stiffness discrimination: Kinneret Teodorescu, Sylvain Bouchigny, Maria Korman To cite this version: Kinneret Teodorescu, Sylvain Bouchigny, Maria Korman. Training haptic stiffness discrimination:: Time course of learning with or without visual information and knowledge of results. Human Factors, SAGE Publications, 2013, 55, pp.830 - 840. 10.1177/0018720812472503. cea-01778365 HAL Id: cea-01778365 https://hal-cea.archives-ouvertes.fr/cea-01778365 Submitted on 6 Jul 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Training Haptic Stiffness Discrimination: Time Course of Learning With or Without Visual Information and Knowledge of Results Kinneret Teodorescu, Technion–Israel Institute of Technology, Haifa, Israel, Sylvain Bouchigny, CEA LIST, Paris, France, and Maria Korman, University of Haifa, Haifa, Israel Objective: In this study, we explored the time INTRODUCTION course of haptic stiffness discrimination learning and how it was affected by two experimental factors, the Haptic perception and skills in general are addition of visual information and/or knowledge of commonly assumed to improve with practice. results (KR) during training. Certain populations, such as musicians, people Background: Stiffness perception may integrate with visual impairments, and surgeons, are both haptic and visual modalities. However, in many associated with superior haptic sensitivity, pre- tasks, the visual field is typically occluded, forcing stiffness perception to be dependent exclusively on sumably attributable to use-dependent or expe- haptic information. No studies to date addressed the rience-dependent neuroplastic mechanisms time course of haptic stiffness perceptual learning. (Dinse, Wilimzig, & Kalisch, 2008). Repeated Method: Using a virtual environment (VE) exposure to sensory experiences results in haptic interface and a two-alternative forced-choice enhanced performance in perceptual tasks and discrimination task, the haptic stiffness discrimination ability of 48 participants was tested across 2 days. Each plastic reorganization of the adult brain (e.g., day included two haptic test blocks separated by a training Karni & Sagi, 1991). However, perceptual block. Additional visual information and/or KR were learning is most extensively studied in the manipulated between participants during training blocks. visual and auditory domains (Goldstone, 1998). Results: Practice repetitions alone induced significant Researchers examining the time course of improvement in haptic stiffness discrimination. Between days, accuracy was slightly improved, but decision time perceptual learning in these domains indicate performance was deteriorated. The addition of visual that at least two different learning processes are information and/or KR had only temporary effects on involved in perceptual learning: fast, within-ses- decision time, without affecting the time course of haptic sion learning, which takes place online (when discrimination learning. stimuli are still present or immediately after); Conclusion: Learning in haptic stiffness discrimination appears to evolve through at least two distinctive phases: and slow, offline learning, or consolidation, A single training session resulted in both immediate and which occurs between sessions (Atienza, latent learning. This learning was not affected by the Cantero, & Dominguez-Marin, 2002; Karni & training manipulations inspected. Sagi, 1993; Sagi & Tanne, 1994). Consolidation Application: Training skills in VE in spaced sessions periods of at least 8 hr may be needed during can be beneficial for tasks in which haptic perception is critical, such as surgery procedures, when the visual wake and sleep time, depending on the task field is occluded. However, training protocols for such demands and design (Karni, Tanne, Rubinstein, tasks should account for low impact of multisensory Askenasy, & Sagi, 1992). Despite its importance, information and KR. only a few studies deal with the time course of Keywords: haptic interfaces, virtual environment, haptic perceptual learning (for example, see human performance, learning, stiffness perception, Adams, Kerrigan, & Graf, 2010, for visual reca- training libration from haptic feedback; Lacey, Pappas, Kreps, Lee, & Sathian, 2009; and Norman, Address correspondence to Kinneret Teodorescu, Clayton, Norman, & Crabtree, 2008, for haptic Technion–Israel Institute of Technology, Haifa, Haifa object recognition; and Wagman, Shockley, 32000, Israel; e-mail: [email protected]. Riley, & Turvey, 2001, for fast perception of HUMAN FACTORS shape characteristics), and none of them focuses Vol. 55, No. 4, August 2013, pp. 830-840 on the perception of stiffness. DOI:10.1177/0018720812472503 Haptics include all aspects of information Copyright © 2013, Human Factors and Ergonomics Society. acquisition and object manipulation through TRAINING HAPTIC STIFFNESS DISCRIMINATION 831 touch by humans, machines, or their combina- visually. In addition, von Kriegstein and Giraud tion; and the environments can be real, virtual, or (2006) found that voice recognition was teleoperated (Srinivasan, Beauregard, & Brock, improved by audiovisual training, proposing that 1996). Mechanical, different sensory, motor, and this effect is not unique for unisensory visual cognitive subsystems work together to create enhancement. Shams and Seitz (2008) concluded haptic percepts and memory (Lederman & that multisensory exposure assists unisensory Klatzky, 2009). While one is touching an object, learning through an activation mechanism in the the haptic system obtains tactile and kinesthesis brain; multisensory learning involves alteration information (information about the displacement of connections between modalities, so that later of the arm together with signals of applied force; presentation of unisensory stimuli activates a Clark & Horch, 1986). In addition, information wider, multisensory network of brain regions. regarding the displacement or deformation of an This proposed mechanism of multisensory facili- object, for example, the finger positions over tation of unisensory learning, if generalized, sug- time, may also be attained from the visual system gests that visual-haptic (VH) training may (Lederman & Klatzky, 2009). These inputs give enhance later haptic performance. rise to a percept of the object’s stiffness. When An additional training manipulation that is there is redundant information from visual and often argued for enhancing performance is haptic modalities, as both arise from the same “knowledge of results” (KR; also known as per- physical event, multisensory integration presum- formance feedback). The origins of this assertion ably occurs (Stein & Meredith, 1993). comes from Thorndike’s law of effect (Thorndike, Stiffness sensitivity is essential for many com- 1927), which implies that responses that produce plex tasks, including medical procedures, such as a satisfying effect become more likely to occur surgery and teleoperation (Howell, Conatser, again, and responses that produce a discomfort- Williams, Burns, & Eland, 2008; Sherman, ing effect become less probable. According to Cavusoglu, & Tendick, 2000). However, in many the law of effect, KR is required to facilitate surgical procedures, the visual field is typically learning, since satisfying or discomforting effects occluded (for example, as in maxillofacial surgery cannot be a result of practice repetition alone. [MFS]); thus the surgeon has to rely solely on the However, in many visual perceptual tasks, per- information obtained from the haptic system. formance was found to improve even when train- Theorists have frequently regarded the haptic ing did not include external KR (e.g., Fahle, modality as inferior to vision in terms of percep- Edelman, & Poggio, 1995; Karni & Sagi, 1991; tual accuracy (Hecht & Reiner, 2009; Kritikos & for a review of visual perceptual learning, see Brasch, 2008; Srinivasan et al., 1996; for the Sagi & Tanne, 1994), suggesting that explicit concept of visual dominance, see Posner, Nissen, feedback is not necessary for perceptual learn- & Klein, 1976). Moreover, recent research on ing. The involvement of internal feedback sig- acquisition of perceptual-motor skills showed nals in perceptual learning is further supported that reliance on visual information occurs even if by studies (Ball & Sekuler, 1987; Shiu & Pashler, a nonvisual strategy is advantageous (Yechiam & 1992) that showed that practice without KR Gopher, 2008). In that case, training with reduced improved performance in easy tasks but not in visual information enhanced performance in difficult ones (in which internal feedback signals tasks in which reliance on haptic information might be ambiguous). was more efficient. Nevertheless, training with external KR is Conversely, recent studies suggest that multi- very common, and there are many experimental sensory experiences may enhance unisensory findings showing an enhancing effect of KR on processing and memory (Lehmann & Murray, performance (e.g., Herzog & Fahle, 1997;