Haptic Exploration in Elementary School Age Children Carol A

Haptic Exploration in Elementary School Age Children Carol A. Coté, PhD, OTR/L key words: perception, cross-modal, tactile

ABSTRACT

Haptic exploration, or active touch, is a perceptual modality that has demonstrated therapeutic potential for elementary age children but is not commonly studied with this age group. The aim of this exploratory study was to discover the characteristics of haptic scanning that are associated with efficiency and accuracy in a shape matching task. The study tasks were designed to resemble common visual perception tests, but in a haptic form using wooden shapes. Children ages 6 years, 6 months to 9 years, 6 months (N = 25), and adults (N = 25) engaged in shape matching tasks that involved either cross-modal (haptic with vision) or unimodal (haptic only) exploration. Video recordings were analyzed and four types of haptic strategies were identified that were significantly related to both age and correctness of response: the simultaneous use of two hands was the highest level and the use of one hand was the lowest. The findings are dis- cussed in terms of attention capacity and ability to use points of reference. [OTJR: Occupation, Participation and Health. 2014; 34(1):4-11.]

he development of haptic (active touch) per- Before we can consider the use of haptic activities ception has long been an area of interest in as a means to a therapeutic goal, a better under- occupational therapy (Cermack, 2006; Hoop, standing of this type of perception is needed. This T1971). Haptic perception is commonly tested (e.g., study investigates haptic exploration in children and Manual Form Perception Test, Ayres, 1989) and adults to determine the characteristics of touch and haptic activities may be used to augment visual movement that are associated with accuracy and activities (Schneck, 2010). Studies have found that efficiency as they use their hands in cross-modal haptic activities can enhance recognition of geo- (vision and haptic) and unimodal (haptic only) metric shapes (Kalenine, Pinet, & Gentaz, 2013) and shape matching tasks. improve phonemic awareness (Bara, Gentaz, Colé, & Sprenger-Charolles, 2004) in kindergarteners. Characteristics of Haptic Scanning Among elementary school age children with learning disabilities, improving haptic exploration strat- In ways comparable to visual scanning, in which egies has been found to improve general percep- the point of focus is moved rapidly from feature to tual skill development (Locher, 1985); however, no feature to encode an image (Henderson, 2007), hands known recent studies have confirmed this finding. can be used to explore and identify an object through Yet research regarding the use of touch as an active haptic scanning by moving the point(s) of contact information gathering tool receives little attention, along the edges of a shape to perceive its image and particularly with children older than preschool age. encode it into short-term memory. Haptic percep-

Dr. Coté is Assistant Professor, Department of Occupational Therapy, University of Scranton, Scranton, Pennsylvania. Submitted: March 16, 2013; Accepted: August 28, 2013; Posted online: November 5, 2013 The author has no proprietary or financial interest in the materials presented herein. Address correspondence to Carol A. Coté, PhD, OTR/L, Department of Occupational Therapy, University of Scranton, Scranton, PA 18510; e-mail: [email protected]. doi: 10.3928/15394492-20131029-05

4 Copyright © American Occupational Therapy Foundation tion of an object requires movement: the fingertips Preschool age children exploring objects hapti- moving across the object stimulate cutaneous sensory cally have been observed using contour following receptors giving information about surface features, patterns similar to those used by adults (Kalagher whereas the movement provides information about & Jones, 2011b; Schwarzer, Kufer, & Wilkening, its spatial characteristics (Klatzky & Lederman, 2003). 1999). Kalagher and Jones (2011a) noted that al- Multiple sources of sensory input (from skin, muscles, though the mature movement patterns may be seen, and joints) are integrated to create this perception they are not used in all circumstances and some (Schaaf & Lane, 2009). The possible combinations of “non-informative” (e.g., “static finger”) hand pat- sensations arising from one to ten fingers, one or two terns have been observed. These observations are hands, and the numerous muscles and joints in the consistent with those noted by Piaget and Inhelder hands and upper extremities, all moving over time, (1967), who described changes in haptic exploration are considerable (Gibson, 1962). Haptic scanning in terms of ability to coordinate exploratory move- strategies must be employed for optimizing input ments. Early in development, approximately 2 to 3 sources and organizing the search. Skill in this area years of age, children can recognize objects, but only would be expected to improve with age because strat- familiar ones, by using global single touches (or egies are learned through experience (Millar, 1999). centrations, in Piaget’s terminology) such as whole Although research on haptic scanning, particu- hand patting. Later, children begin to coordinate larly with children, is sparse, some characteristics of successive haptic perceptions and can recognize haptic behavior that have been reported may be im- abstract objects. By approximately 6 to 7 years of portant to consider in investigating scanning strate- age, children use a fixed point of reference to orga- gies. One characteristic is the use of one versus two nize perceptions and are considered at the highest hands. Klatzky, Lederman, and Balakrishnan (1991) level of haptic perceptual activity. Based on Piaget’s provided a detailed account of the patterns of move- work, Hoop (1971) recorded the haptic explorations ment used by adults as they explored novel shapes of preschoolers using a point system for the types with the purpose of making specific comparisons. of exploration and the levels of organization dem- Two-hand use was nearly universal, and the use of onstrated. The highest points were given for using two hands moving together was noted as having a constant point of reference (holding in a constant high persistence during the tasks. Two-hand explo- place with one hand while the other explores). The ration has been seen as a positive development as- oldest children, 5½ year olds, obtained the highest sociated with successful matching in children (Bush- scores reflecting the most systematic exploration. nell & Baxt, 1999; Kalagher & Jones, 2011a), and with No recent research was found on the Piaget- adults the use of two hands (on instruction of one or ian view of the development of points of reference two hand use) leads to increased salience of shape in haptic exploration, and little (recent or old) (Klatzky, Lederman, & Reed, 1989). Also, in a differ- addresses the haptic skills of children older than ent type of tactile activity, two-handed (or -fingered) preschool from any theoretical base. Yet general per- Braille readers tend to be faster than one-handed ception continues to develop through childhood, readers (Millar, 1987). Millar (1999) described the as noted by Piaget and Inhelder (1967) and as evi- use of two hands as providing a frame of reference, denced in many standardized visual perception tests each hand a reference for the other. (e.g., TVPS-R, Gardner, 1996). The early elementary The hand and finger movements used in haptic school years are also a time when concerns about scanning of an object have also been investigated. In visual perception and visual motor skills arise and adults, Lederman and Klatzky (1987) identified con- may be addressed by occupational therapists. There- tour following as the type of hand movement used fore, an investigation of the haptic perceptual abili- to identify the exact shape of an object, “a dynamic ties of early elementary school children could pro- (exploratory procedure) in which the hand maintains vide useful information for therapists. contact with the contour of the object” (p. 347). In Klatzky et al. (1991), the most common patterns ob- Cross-Modal Transfer served were those using multiple points of contact with the object and molding fingers around a shape Studies that investigate haptic perception often or part of the shape (enclosure). Single-handed simple use tasks of matching an object by feel to a visual contour following was only occasionally observed. choice, known as a cross-modal transfer. Therefore, Combinations of enclosure and movement, such as an important component of many haptic percep- the thumb and index following along a convex fea- tion tasks is the connection with visual processes. ture ending in a pinch, were also frequently seen. Cross-modal transfer is an ability that has a devel-

OTJR: Occupation, Participation and Health • Vol. 34, No. 1, 2014 5 opmental trajectory that begins very early in life (for Schwarzer et al., 1999); therefore, a more complex a review of early development, see Cermak, 2006). haptic task is needed to observe differences between Preschoolers have been noted to be able to recognize school age and full maturity. The assumed connec- both familiar and unfamiliar objects in haptic-to- tion between visual and haptic perception provides visual matching tasks, but are less proficient at this the inspiration for the study tasks: a typical visual than mature participants (Bushnell & Baxt, 1999; Ka- perception test, similar to those used in standard- lagher & Jones, 2011a). By age 6 years, children have ized visual-perception tests, has been transformed been found to be equal to adults on cross-modal into a haptic perception test by making either the categorization tasks (Garbin, 1990), although on a target or choices, or both, out of wood. Because difficult task (precise size discrimination task with the study tasks involve several shapes presented at conflicting visual and haptic information) optimal once, a strategy for exploration and maintaining in- integration may not occur until approximately age formation must be employed to satisfy the goal of 10 years (Gori, Del Viva, Sandini, & Burr, 2008). identifying an exact match. The study tasks proceed Even in the absence of an actual visual referent, from an all-visual matching task to a mix of haptic haptic recognition is believed to share some of the and visual and finally to an all-haptic matching task. same perceptual phenomena as visual images, gener- This order allows participants to become familiar ating a mental representation of the percepts arising with the demands of the haptic matching tasks and from touch and movement (Gibson, 1962; Piaget & In- provides an opportunity to observe strategy differ- helder, 1967). The nature of cross-modal perception, ences in haptic-visual compared to haptic only tasks. whether it is a single multisensory representation or The target group of this study was elementary an integration of two separate representations, is a school age children. A group of college undergrad- current topic of debate in cognitive psychology. (For uates was also included to provide a measure of a summary of current research in this area, see Lacey, mature skill development. This is an exploratory Campbell, & Sathian, 2007.) Additionally, neurologi- descriptive study conducted to discover the haptic cal evidence supports the integration of the two mo- scanning patterns and strategies for organizing ac- dalities. For example, functional magnetic resonance tions that may be related to efficiency and accuracy imaging studies of the brain show that parts of the in a shape matching task. visual system are activated during haptic exploration (James et al., 2002) and transcranial magnetic stimu- Methods lation used to interfere with the visual cortex results Participants in impaired tactile perception (Sathian & Zangaldze, Participants included a convenience sample of 2002). The current study was designed to observe 25 early elementary school age children 6 years, 6 patterns of exploration in both cross-modal and sin- months to 9 years, 6 months (mean age: 8-2 years); 10 gle modality conditions. were male. Children were from local families known Haptic shape perception is a highly cognitive, to university employees. They had no known learning multimodal ability requiring short-term memory or sensory disabilities according to parent report. of sensations over time, perceptual abilities, and a Each child received a stipend of $10 and the parent re- strategy for gathering information. The characteris- ceived $25. The adult group included 25 undergradu- tics of haptic perception that have been found to be ate university students; eight were male. The adults associated with skill development are the use of two participated either voluntarily or in fulfillment of a hands (rather than one), the coordination of multiple course requirement. The Institutional Review Board touches (rather than single or static touching), and of the University of Scranton approved this study. For the use of a constant reference point. Because nearly children, parental consent and participant assent was all previous research has investigated the haptic ex- obtained; adults provided informed, signed consent. ploration of children up to preschool age and adults, information about how elementary school age chil- Set-up dren explore by touch is needed to more fully under- Participants sat at a table in an appropriately sized stand perceptual development at this age. chair. Directly in front of the participant was a 12 3 24 inch platform raised 8 inches off the table. The hap- Current Study tic task items were presented under this platform by an investigator from the other side of the table. A It has been shown that by preschool age children cloth draped over the front of the platform prevented generally use adult-like exploration patterns for the participant from seeing the items. The matching single object exploration (Kalagher & Jones, 2011b; choices for the haptic-visual tasks were shown on

6 Copyright © American Occupational Therapy Foundation a 20-inch computer monitor positioned beyond the platform at eye level to the participant. A small web- cam with auditory recording was directed to the area under the platform, where it recorded participants’ hand movements and their vocalizations.

Study Tasks The following tasks were used in this study. The aim was to make the type of shapes used in both visual and haptic conditions similar, solid forms vary- ing in contour of the edges. The wood cut-out shapes used in the haptic tasks were affixed to a board to maintain the orientation and order of choices. Vision Only. Items were shown on the computer screen. Each task item had a target shape positioned top and center, and four match choices aligned horizontally below target. Six items were given. HV/1 (Haptic-Visual Matching/One Form). This Figure 1. Sample item from each study task. Top: task was intended to serve as an introduction to the Vision Only and Haptic-Visual Matching/One Form multi-form haptic tasks. A single wood shape mea- (HV/1). Bottom: Haptic-Visual Matching/Four Forms suring approximately 3 3 3 inches and ¼-inch thick (HV/4) and Haptic-Visual Matching/Five Forms (H/5). was affixed to a larger board that could be moved in and out of the space below the platform. Four choices for matching were presented on the monitor. One shapes. The board for each task item was placed in practice item, then two test items were given. the space behind the curtain. When the participant HV/4 (Haptic-Visual Matching/Four Forms). Four was instructed to “go ahead,” the visual matching wood shapes of similar design measuring approxi- choices appeared on the computer screen. Partici- mately 2 3 2 inches were affixed to a board. A vi- pants voiced their choice (e.g., “the third one”). sual target that matched one of the wood shapes was The two multi-shape tasks, HV/4 and H/5, were shown on the monitor. One practice item and then then presented, each with a sample board provided three test items were given. in full view to the participant prior to the test items. H/5 (Haptic-Only Matching/Five Forms). Five Instructions were given to find the match to the sin- 2 3 2 inch wood shapes were affixed to a board. gle visual shape on the screen for HV/4 and to find One shape was the target, placed top and center, and the match to the top shape on the board for H/5. four matching choices were aligned horizontally be- Participants were encouraged to tap on their choice low the target. One practice item and then three test rather than name it by number to avoid confusion as items were given. Samples of each task are shown in to the shape’s serial position. Figure 1. Data Procedure The main focus of this study was on the patterns Participants were shown the first Visual Only of exploration used by participants in the HV/4 and task item and were instructed, “See the shape on the H/5 tasks, the tasks that involved multiple shapes to top?” with the examiner pointing, “Find which shape feel. The Visual Only task served as an introduction down here matches that top shape exactly. You can and it was intended that errors would be used to as- say one, two, three, or four.” The test items were then sess efficacy of visual scanning; however, few errors presented. Next, the HV/1 activity was introduced were made and thus it is not analyzed further. HV/1 with a sample of a wood shape affixed to a board and task, although also used as an introduction, was ana- presented on top of the platform in full view. Partici- lyzed for strategies, particularly to compare to earlier pants were encouraged to feel the shape and were research findings on single form haptic exploration told that their job will be to feel a shape behind the (e.g., Klatzky, Lederman, & Balakrishnan 1991). Be- curtain and match it to one shown on the comput- cause only one haptic form was involved in this task, er screen. The examiner then lifted the curtain that it is not included in the analyses of multi-shape items. covered the space below the platform, showing the Determining the patterns of hand movements participant the area to be used for feeling the wood used by the participants during haptic exploration

OTJR: Occupation, Participation and Health • Vol. 34, No. 1, 2014 7 involved several steps. First, the author repeatedly Because time was not controlled (i.e., no instruc- reviewed the HV/4 and H/5 videos and identified tions to “answer as fast as you can”), and because three potential general categories of strategies (one of great variability, time to respond was not further hand, two hands used symmetrically on one shape analyzed. SPSS package 17.0 (SPSS, Inc., Chicago, at a time, and two hands on separate shapes). Next, IL) was used for data analysis. three student research assistants were given the de- scriptions of those strategies and together they re- Results viewed the videos and assigned one strategy to each task item. They were encouraged to critique the cat- Inspection of the video recordings of participants’ egories. They were blind to the age of the participant hand movements revealed the following strategies (it was generally not possible to determine age by for haptic exploration of the single- and multi-shape video of hands alone). During this process we de- tasks. cided that the final category should be divided into two: two hands alternating and two hands simulta- HV/1 Strategies neous (fully described below). In some cases more The common strategy used by participants to de- than one strategy was employed during a single termine the match of a single shape to visual choic- task item; then the strategy used for determining the es was to feel the contours that differentiated the match was counted. Thus, a participant may have choices; in the example in Figure 1, that would be used one strategy to explore the shapes but a differ- top bump and bottom contours of the shape. Nearly ent strategy to recheck the final answer; this would all participants used a combination of enclosure and be coded as using the first strategy. movement, or dynamic enclosure. Enclosure was in- After the group assigned one of the four strategies dicated by multiple contact points, either with two to each task item for each participant, a different stu- hands and/or with two or more fingers on one hand dent assistant, naïve to the purpose of the study, was (usually thumb and another finger). Two children, given a description of the four strategies and was in- both 7-year-old boys, used a simple contour follow- structed to code each observation according to which ing procedure (one finger) in which the edges of the was used predominantly to arrive at the choice (and shape were felt in the absence of a reference finger, not initial orientation or re-checking choice). This similar to tracing the shape, and each made one of reviewer agreed with the original coding on 82% of the only eight errors seen in this activity. The ma- items. The disparity came mostly from whether two jor strategy difference found between the two age hands were used alternately or simultaneously. groups was the use of one hand versus two hands; To provide an objective measure of the question- 44% of the children used one hand for feeling the able videos, the group of student research assistants shape, compared to 16% of adults. reviewed them again slowly, by 1-second intervals, and tallied whether one or two hands were moving HV/4 Strategies during each second. A few item recordings remained In this task that included four shape choices to difficult to determine which strategy was used be- feel, four strategies were observed. Two strategies cause more than one was observed. Because these observed were similar to those seen in HV/1: one items were mostly from children, and because it was hand feeling the shapes (1H) and two hands simul- apparent from our observations that there was a pro- taneously feeling the contours of one shape at a time, gression in skill level associated with these strategies often using symmetrical movements (2H-sym). Two (later confirmed in data analysis), a liberal standard new strategies unique to multi-shape exploration was adopted to ensure the participant received cred- were observed: two hands used with one feeling a it for the highest level strategy. A threshold of one- shape and the other keeping place elsewhere on the third (not the majority) of seconds showing highest array, hands may switch roles mid-task but were level strategy resulted in categorizing the item at used alternately (2H-alt), and two hands simultane- that level because it showed that the participant was ously feeling two different shapes (2H-sim). Using a able to employ that strategy. 2 3 4 (age group 3 strategy) Pearson chi-square test, Each participant was coded for one strategy (the adults differed significantly from children in strat- highest level observed) for each task item. This re- egy use (chi-square [3] = 11.56, p = .009). Adults were sulted in 100 observations for HV/1 (50 participants more likely to use two hands on different shapes 3 2 items) and 300 observations for HV/4 and H/5 (2H-alt and 2H-sim) and children were more likely (50 participants 3 6 items). Correctness of choice and to use 1H. Figure 2 shows the proportion of each time to respond for each item were also recorded. strategy by age group.

H/5 Strategies With both the target and choices explored haptically, nearly all participants explored the target shape first. Then four strategies for finding choices were observed that were similar to those seen in the HV/4 tasks: one hand feeling all shapes occasionally returning to the target for recheck (1H); two hands simultaneously feeling the contours of each shape and target one at a time (2H-sym); two hands used with one hand remaining on target while the other explores the choices, hands working alternately (2H- alt); and two hands with one hand remaining on target while the other explores, both hands simultane- Figure 3. Errors as a proportion of total of each type ously active (2H-sim). Occasionally participants felt of strategy. two choices, rather than the target and a choice, during part of the exploration. Adults again differed sig- Age-Related Differences in Children nificantly from children in strategy use (chi-square Spearman correlation showed no significant rela- [3] = 28.92, p < .001). Adults were more likely to use tionship between the age of the child and the strat- two hands on different shapes; however, 2H-sim egy (ordered 1 to 4 by level) used on any of the six was now their most common strategy. Children multi-shape tasks, although a positive trend toward again were more likely to use 1H or 2H-sym. Figure the higher level with age was noted. Correlations 2 shows the frequency of each strategy by group. ranged from r = .098 to .390.

Assignment of Strategy Levels Discussion The four strategies were ranked in order of apparent effectiveness and maturity, with 1H the lowest Using touch to find an exact match of a shape from level and 2H-sim the highest. Effectiveness of a strat- an array of choices requires a strategy for coordinat- egy was judged by the proportion of errors associated ing multiple sources of input (tactile and propriocep- with each strategy (Figure 3). Children made the large tive) to create a percept of the shape and maintaining majority of errors (85%) and errors were more likely that percept over time as options are explored. This found in the lower level strategies (chi-square [3] = study sought to discover the strategies used by two 15.05, p = .002). Maturity was judged by each strat- different age groups, elementary school age children egy’s association with the two age groups and this and adults, during haptic exploration. Four catego- ordering was consistent with the ordering by errors. ries of strategies emerged: one hand exploring, two

OTJR: Occupation, Participation and Health • Vol. 34, No. 1, 2014 9 hands symmetrically exploring one shape at a time, The findings are consistent with Piaget and Inhel- two hands alternating between one shape and anoth- der (1967), Hoop (1971), and Millar (1999): when two er, and two hands simultaneously exploring differ- hands are used they can act as a spatial anchor or ent shapes. With only one shape to explore, patterns reference point for each other. The ability to make similar to those noted by Klatzky et al. (1991) and use of frames of reference is a central tenet in Piag- Kalagher and Jones (2011a; 2011b) were observed. etian theory of general perceptual development and Nearly all participants used multiple points of con- not limited to haptic perception. Here, the use of tact moving around the edges, or dynamic enclo- one hand as a reference was associated with more sure. The main difference between the groups was effective strategies, in terms of accuracy, for explo- that children were less likely than adults to use two ration. Evidence was found for a developmental hands, a finding that is consistent with Bushnell and trend in strategy use. Although the trend was not Baxt (1999) and Kalagher and Jones (2011a). significant within this small sample of children, the The unique aspect of this study was the use of differences between the children as a group com- multi-shape haptic tasks. In these tasks, new char- pared to adults were significant. It should be noted acteristics of exploration were identified. The use of that there was considerable individual variation two hands in two different places on an array was as- in both age groups; some of the youngest children sociated with adult performance and with relatively used the highest level, whereas some adults used the few errors. Participants were not given specific in- lowest level strategy, indicating that development of structions to use two hands, and it is possible that strategy use is not absolutely related to age. children simply did not think to use a second hand. There were several limitations with this study. The However, it was observed that several children had coding of strategies was created for this study; there- the second hand inside the feeling area; one was fore, further studies are needed to confirm they rep- even coached to use the second hand (erroneously, resent developmental levels. Also, haptic matching by a parent) but still did not use it. When given mul- was a new experience for the participants for which tiple shapes to explore, most adults and only some they may not have had a ready strategy. Perhaps with children used two hands separately to gather infor- more exposure some participants might have discov- mation from two shapes at the same time. This pro- ered a more effective strategy for the task. gression may reflect an ability to process more information at one time, perhaps a haptic instance of a Implications for Occupational Therapy Practice theory of limited attentional capacity (e.g., Cowan et and Future Research al., 2005) or M-capacity (e.g., Morra, 1994). The use Evidence supports the incorporation of a hap- of only one hand or two hands on one shape may tic component into some areas of early elementary have a low demand on attentional capacity, whereas learning (Bara et al., 2004; Kalenine et al., 2013). Be- two hands on different places on the array may re- cause occupational therapy practitioners often en- quire greater capacity, particularly if the two hands gage children in multi-sensory experiences as part were simultaneously gathering information. of treatment, practice would benefit from a greater In the HV/4 tasks, it was rare for even adult par- understanding of the development of haptic explora- ticipants to use the 2H-sim strategy. This task had a tion. In this study, it was found that the use of two visual target and thus the vision modality was used hands rather than one was related to mature and ac- to actively explore the target while the haptic modal- curate performance, and the coordinated use of the ity was used to explore the choices at the same time. two hands, with one maintaining contact with the It has been reported that cross-modal perception ex- target as a reference, was optimal. Therapists using acts a cost to attention for each modality; attention is haptic activities as part of a multi-sensory learning not additive with two sources of information, rath- experience (e.g., learning letters and shapes) might er it appears to be at least partly shared (Hatwell, encourage the child’s use of two hands, one as a refer- 2003). In the H/5 task, both the target and the choic- ence and the other exploring, during these activities. es were presented haptically and more participants, An important area of research for occupational almost exclusively adults, used one hand for active therapy would be to determine whether haptic ex- exploration of the target while the other explored ploration can improve with practice and to confirm the choices, thus two separate sources of simultane- the Locher (1985) findings that improvement in hap- ous information within one modality. This suggests tic exploration could lead to general improvement in that greater attentional resources were available for perceptual skills such as the spatial relations and part- haptic perception in the haptic-only tasks than for whole perception that underlie pencil-and-paper and cross-modal tasks, particularly for adults. construction activities. An unexpected finding was

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