Find the Missing Element! Haptic Identification of Incomplete Pictures ...
Find the Missing Element! Haptic Identification of Incomplete Pictures by Sighted and Visually Impaired Children Anaïs Mazella1,2, Jean-Michel Albaret1, and Delphine Picard2,3 Université Toulouse III Paul Sabatier, PRISSMH EA4561, 31058 Toulouse, France 2 Aix Marseille Université, PSYCLE EA3273, 13621 Aix en Provence, France, 3Institut Universitaire de France, Paris, France [email protected], [email protected], [email protected] 1
Abstract. This study investigates the haptic identification of incomplete raised-line drawings (i.e., pictures with a missing element) by sighted and early visually impaired children aged 9-10 years. Incomplete pictures have already been used in the visual modality to assess perceptual reasoning in children, but not yet under the haptic modality. We found that success at identifying incomplete raised-line pictures (correct naming of object plus missing feature) concerned 32.65% of children’s responses, suggesting that the task was hard although not entirely impossible. Overall, the visually impaired children outperformed the sighted controls at this task. However, there was a large variation in responses across items, and the superiority of the visually impaired children over their sighted peers was not systematic. We concluded that adapting materials from the Wechsler’ image completion subtest to the haptic modality may be relevant to investigate haptic perceptual reasoning in children with and without visual impairments.
Keywords: Haptic perception; Incomplete raised-line pictures; Visual impairment.
1 Introduction Haptics and vision differ greatly in how they process incoming information. Vision usually proceeds from global apprehension to more local understanding of a display. Unlike vision, haptics proceeds more analytically due to the inherent constraint of serial processing of information within a limited perceptual field [1], [2]. Local processing thus dominates in early stages of haptic perception; access to the global structure of a stimulus occurs later in the course of information processing as it requires a mental integration of sequentially and locally gathered information [3]. Incomplete pictures, that is to say pictures with a missing feature (e.g., the picture of a comb with a missing tooth), have already been used in the visual modality to assess perceptual reasoning in children. Indeed, a famous subtest of the Wechsler Intelligence Scale for Children ([4]; 4th French revised version) is that of “picture compleadfa, p. 1, 2011. © Springer-Verlag Berlin Heidelberg 2011
tion”. This subtest presents children with a series of incomplete pictures of common objects and requires that children identify the missing part of familiar objects’ drawings using their sense of vision. This nonverbal subtest assesses children’s ability to perceive and organize a visual array, as well as their concentration and sense of detail. In the present study, we used incomplete raised-line pictures as a material for haptic identification purpose, so as to investigate children’s perceptual reasoning under the haptic modality. We tested haptic perception of incomplete raised-line drawings in sighted and visually impaired children aged 9-10 years, so as to examine (1) whether (and possibly how) children can identify incomplete raised-line pictures through haptics, and (2) how visually impaired children and age-matched sighted controls compare in such a task. Regarding issue 1, it is not clear as to whether a disruption (missing feature) in the configural properties of a stimulus (raised-line drawing) actually hinders the haptic processing and recognition of that stimulus. A recent study by Puspitawati, Jebrane and Vinter [5] suggests that children are attentive to local and small size units when exploring a raised-line configuration, and hardly come to a global coherent percept of the stimulus; accordingly, we may hypothesise that the (initial and predominant) local processing in haptic perception would not constitute a major handicap to perceive and make sense of incomplete stimuli. Regarding issue 2, previous studies have shown an advantage of visually impaired children over sighted controls when pictures depict complete objects (e.g., [6], [7]). The present study explores whether this advantage still holds true in case where pictures have a missing feature.
2 Method 2.1 Participants Participants were 13 visually impaired children (10 boys, 3 girls; Mean age = 121 months, SD = 7), and 13 sighted children (7 boys, 6 girls; Mean age = 122 months, SD = 6). The visually impaired children all had an early visual impairment (i.e., either congenital or acquired during childhood); two were totally blind (light perception at best), five were legally blind (best corrected visual acuity below 1/10), and seven had low vision (best corrected visual acuity below 4/10). They attended French specialized care centres for the sensory disables (Alfred Peyrelongue, and Cival-Lestrade centres). They had a moderate practice with tactile pictures at home or school. The sighted controls were recruited from normal schools and matched for chronological age with the visually impaired children. None of the sighted children had used raisedline pictures before the study. 2.2 Material The stimuli were 8 incomplete raised-line pictures depicting common objects, adapted from the image completion subtest of The Wechsler Intelligence Scale for Children (4th French revised version; [4]). The picture set appears in Fig. 1.
Fig. 1. Responses distribution by group for each item (* items for which response distribution varied significantly according to group).
None of the pictures contain any information about the third dimension. The raisedline pictures were produced on Swell paper with a heating machine (largest picture dimension: 19 x 25 cm). We used a wooden box with an opaque curtain to hide the test material from the participants’ view. This equipment permitted children to put their hands below the curtain, and to explore the tactile drawings haptically, without visual access to the pictures. 2.3 Procedure Children were tested individually in a quiet room inside their school or centre for blind children. They were asked to explore freely a series of 8 incomplete raised-line drawings in order to identify as quickly and accurately as possible what the drawing represented and which element was missing. In order to familiarize children with the task, two additional raised-line drawings were used for practice. Children were allowed up to 2 min of exploration per picture and one answer (i.e., including both object and missing element) per trial. Prior to the presentation of each picture, the category name of the depicted object was given to the participants (e.g., instrument for item 7) (see [8] for a similar procedure). We selected this option because pre-tests without semantic cues revealed floor performance in children. During the test, no feed-back was given, regardless of the nature of the response.
3 Results Children’s responses fall into 4 possible categories: I. Object and element (participants identified both the object and the missing element); II. Object only (participants could only identified the object); III. Element only (participants could only identify the missing element); IV. None (participants could neither identify the object nor its missing element). Table 1. Responses distribution in percent for each group (all items together).
The results (see Table 1) indicated that, when both groups were taken together, responses from category IV predominated (47.65%), followed by responses from category I (32.65%). However, the response distribution varied clearly according to group. The dominant response of the sighted children was failure to identify both the object and the missing element (category IV: 58.7%). By contrast, the visually impaired children succeeded frequently at the task (category I: 42.3%), at least far more than the sighted children did (category I: 23%). For both groups, responses from category II occurred quite often (16.85%), whereas responses from category III were very
rare (2.85%). This meant that part of the children were able to name the object without identifying the missing element. By contrast, children rarely identified the missing element only. When we calculated a recognition score (0-8 points, with 0.5 point per picture when children found the expected name of the object, plus 0.5 point for the missing element), we found significant between-group difference with the visually impaired children scoring higher (M = 4.23, SD = 1.98) than the sighted children (M = 2.50, SD = 1.54), Mann-Whitney U-test, p = 0.0333. When we look at the distribution of responses for each item separately (see Fig. 1), we observed a large variation in responses across items. Three different patterns emerged. In pattern 1, children’s responses were fairly distributed among the 4 categories: this pattern concerned Item 1 (Girl), and Item 6 (Sweater). The distribution of responses did not vary significantly according to group for these two items (Girl: Fisher exact test, p = 0.687; Sweater: Fisher exact test, p = 0.474). In pattern 2, children’s dominant response was failure to identify both the object and the missing element: this pattern concerned Item 2 (Hand), Item 3 (Comb), and Item 4 (Scissors). For these three items, the failure rate was high in participants (69.5% for Hand, 73% for Comb, and 61.5% for Scissors). The distribution of responses did not vary significantly according to group for Item 2 (Hand: Fisher exact test, p = 0.719), and Item 3 (Comb: Fisher exact test, p = 0.573). However, for Item 4 (Scissors), the distribution of responses varied significantly according to group (Fisher exact test, p = 0.010): failure to identify both the object and its missing element was the dominant response of the sighted children, but not that of the visually impaired children who could, for part of them, identify the object as scissors. Finally, in pattern 3, children’s dominant response was success to identify both the object and the missing element: this pattern concerned Item 5 (Ladder), Item 7 (Guitar), and Item 8 (Clock). For these three items, the identification rates were quite great in participants (50% for Ladder and Guitar, and 53.8% for Clock). The distribution of responses varied significantly according to group for Item 5 (Ladder: Fisher exact test, p = 0.048), and Item 7 (Guitar: Fisher exact test, p = 0.011), but not for Item 8 (Clock: Fisher exact test, p = 0.532). For Items 5 and 7, success to identify both the object and element was the dominant response of the visually impaired children, but not that of the sighted children who mainly failed to identify the object and its missing element.
4 Conclusion Three main findings emerged from the study. First, success at identifying incomplete raised-line pictures through haptics (naming object plus missing feature) concerned 32.65% of children’s responses, suggesting that the task was hard although not entirely impossible (see [8]). Interestingly, part of the children was able to identify the object without the missing feature, but the reverse quite never occurred. In line with our hypothesis, these findings suggest that a disruption (missing feature) in the configural properties of a stimulus (raised-line drawing) did not hinder the haptic processing and recognition of that stimulus in terms of object representation. It is likely that children paid attention to local and small size units when exploring the raised-line configura-
tions; they may have guessed what a given picture could depict in terms of object representation, before they were able to identify the missing element through further analytical examination of the stimulus (see also [5]). To what extent children who succeeded at the task constructed an internal representation of raised-line pictures which integrated local parts into a coherent whole is however unknown, and may call for further investigations. Second, we found that overall the visually impaired children outperformed the sighted controls at the incomplete picture identification task. This finding confirms the overall superiority of visually impaired children over their sighted peers in haptic picture perception tasks (see [6], [7], [10]), and extents this observation to the haptic processing of incomplete pictures. Third, we found large variations in children’s responses to incomplete pictures across items, and observed that the superiority of the visually impaired children over their sighted peers was not systematic, as it depended on the item to be processed. In conclusion, findings from this study lead us to suggest that adapting materials from the Wechsler’ image completion subtest to the haptic modality may be relevant to investigate haptic perceptual reasoning in children with and without visual impairments. The development and/or adaptation of tests for visually impaired children is still a challenge, as only a limited number of psychometric tools are currently available (see e.g., [11] and [12] for a review). However, because the task was rather difficult, even for the visually impaired children, it would be worth completing these experimental results with scores obtained by older participants (sighted and visually impaired) in order to demonstrate that the task can be achieved with a rather good level of performance at the end of childhood. The next step of our research project therefore consists in collecting data with a larger sample of participants, including children, adolescents, and young adults, with and without visual impairment. Moreover, as suggested by several authors [13-14], it might be necessary to proceed to separate standardizations in order to take the diversity inherent to the visually impaired people into account (associated disorders, visual status, individual's visual experience…).
Acknowledgments This work was supported in part by a grant from the PRES of Toulouse and Région Midi-Pyrénées attributed to the first author for her PhD Thesis. We thank Mélanie Labardin, Cival-Lestrade Centre, Sandra Mesnières, Alfred Peyrelongue Centre, and the children who took part in the study.
References 1. Berger, C., Hatwell, Y.: Dimensional and Overall Similarity Classification in Haptics: A Developmental Study. Cog. Dev. 8, 495-516 (1993) 2. Lederman, S.J., Klatzky, R.L.: Haptic Perception: A Tutorial. Atten. Percept. Psychophys. 71, 1439-1459 (2009) 3. Hatwell, Y., Streri, A., Gentaz, E.: Touching for Knowing. Philadelphia PA. John Benjamins Publishing Compagny (2003)
4. Wechsler, D.: WISC-IV, Echelle d’Intelligence de Wechsler pour Enfants et Adolescents. Paris. ECPA (2005) 5. Puspitawati, I., Jebrane, A., Vinter, A.: Local and Global Processing in Blind and Sighted Children in a Naming and Drawing Task. Child Dev. (in press) 6. D’Angiulli, A., Kennedy, J.M., Heller, M.A.: Blind Children Recognizing Tactile Pictures Respond like Sighted Children given Guidance in Exploration. Scand. J. Psychol. 39, 187190 (1998) 7. Pathak, K., Pring, L.: Tactual Picture Recognition in Congenitally Blind and Sighted Children. Appl. Cog. Psychol. 3, 337-350 (1989) 8. Heller, M. A., Calcaterra, J. A., Burson, L. L., Tyler, L. A.: Tactual Picture Identification by Blind and Sighted People: Effects of Providing Categorical Information. Perception & Psychophysics 58, 310-323 (1996) 9. Picard, D., Lebaz, S.: Identifying Raised-Line Pictures by Touch: A Hard-but not Impossible-Task. J. Vis. Impair. Blind. 106, 427-431 (2012) 10. Vinter, A., Fernandez, V., Orlandi, O., Morgan, P.: Exploratory Procedures of Tactile Images in Visually Impaired and Blindfolded Sighted Children: How they Relate to their Consequent Performance in Drawing. Res. Dev. Disabil. 33, 1819-1831 (2012) 11. Ballesteros, S., Bardisa, D., Millar, S., Reales, J. M.: The Haptic Test Battery: A New Instrument to Test Tactual Abilities in Blind and Visually Impaired and Sighted Children. Brit. J. Vis. Impair. 23, 11-24 (2005) 12. Mazella, A., Albaret, J-M., Picard, D.: Haptic Tests for Use with Children and Adults with Visual Impairment: A Literature Review. J. Vis. Impair. Blind. (in press) 13. Bonnardel, R., Baton, C., Thiebaut, E.: Test d’Intelligence Pratique pour Déficients Visuels: B101DV. Talant. Les Doigts Qui Revent (2010) 14. Dekker, R.: Visually Impaired Children and Haptic Intelligence Test Scores: Intelligence Test for Visually Impaired Children (ITVIC). Dev. Med. & Child Neurol. 35, 478-489 (1993)
Abstract. This study investigates the haptic identification of incomplete raised-line drawings (i.e., pictures with a missing element) by sighted and early visually impaired children aged 9-10 years. Incomplete pictures have already been used in the visual modality to assess perceptual reasoning in children, but not yet under the haptic modality. We found that success at identifying incomplete raised-line pictures (correct naming of object plus missing feature) concerned 32.65% of children’s responses, suggesting that the task was hard although not entirely impossible. Overall, the visually impaired children outperformed the sighted controls at this task. However, there was a large variation in responses across items, and the superiority of the visually impaired children over their sighted peers was not systematic. We concluded that adapting materials from the Wechsler’ image completion subtest to the haptic modality may be relevant to investigate haptic perceptual reasoning in children with and without visual impairments.
Keywords: Haptic perception; Incomplete raised-line pictures; Visual impairment.
1 Introduction Haptics and vision differ greatly in how they process incoming information. Vision usually proceeds from global apprehension to more local understanding of a display. Unlike vision, haptics proceeds more analytically due to the inherent constraint of serial processing of information within a limited perceptual field [1], [2]. Local processing thus dominates in early stages of haptic perception; access to the global structure of a stimulus occurs later in the course of information processing as it requires a mental integration of sequentially and locally gathered information [3]. Incomplete pictures, that is to say pictures with a missing feature (e.g., the picture of a comb with a missing tooth), have already been used in the visual modality to assess perceptual reasoning in children. Indeed, a famous subtest of the Wechsler Intelligence Scale for Children ([4]; 4th French revised version) is that of “picture compleadfa, p. 1, 2011. © Springer-Verlag Berlin Heidelberg 2011
tion”. This subtest presents children with a series of incomplete pictures of common objects and requires that children identify the missing part of familiar objects’ drawings using their sense of vision. This nonverbal subtest assesses children’s ability to perceive and organize a visual array, as well as their concentration and sense of detail. In the present study, we used incomplete raised-line pictures as a material for haptic identification purpose, so as to investigate children’s perceptual reasoning under the haptic modality. We tested haptic perception of incomplete raised-line drawings in sighted and visually impaired children aged 9-10 years, so as to examine (1) whether (and possibly how) children can identify incomplete raised-line pictures through haptics, and (2) how visually impaired children and age-matched sighted controls compare in such a task. Regarding issue 1, it is not clear as to whether a disruption (missing feature) in the configural properties of a stimulus (raised-line drawing) actually hinders the haptic processing and recognition of that stimulus. A recent study by Puspitawati, Jebrane and Vinter [5] suggests that children are attentive to local and small size units when exploring a raised-line configuration, and hardly come to a global coherent percept of the stimulus; accordingly, we may hypothesise that the (initial and predominant) local processing in haptic perception would not constitute a major handicap to perceive and make sense of incomplete stimuli. Regarding issue 2, previous studies have shown an advantage of visually impaired children over sighted controls when pictures depict complete objects (e.g., [6], [7]). The present study explores whether this advantage still holds true in case where pictures have a missing feature.
2 Method 2.1 Participants Participants were 13 visually impaired children (10 boys, 3 girls; Mean age = 121 months, SD = 7), and 13 sighted children (7 boys, 6 girls; Mean age = 122 months, SD = 6). The visually impaired children all had an early visual impairment (i.e., either congenital or acquired during childhood); two were totally blind (light perception at best), five were legally blind (best corrected visual acuity below 1/10), and seven had low vision (best corrected visual acuity below 4/10). They attended French specialized care centres for the sensory disables (Alfred Peyrelongue, and Cival-Lestrade centres). They had a moderate practice with tactile pictures at home or school. The sighted controls were recruited from normal schools and matched for chronological age with the visually impaired children. None of the sighted children had used raisedline pictures before the study. 2.2 Material The stimuli were 8 incomplete raised-line pictures depicting common objects, adapted from the image completion subtest of The Wechsler Intelligence Scale for Children (4th French revised version; [4]). The picture set appears in Fig. 1.
Fig. 1. Responses distribution by group for each item (* items for which response distribution varied significantly according to group).
None of the pictures contain any information about the third dimension. The raisedline pictures were produced on Swell paper with a heating machine (largest picture dimension: 19 x 25 cm). We used a wooden box with an opaque curtain to hide the test material from the participants’ view. This equipment permitted children to put their hands below the curtain, and to explore the tactile drawings haptically, without visual access to the pictures. 2.3 Procedure Children were tested individually in a quiet room inside their school or centre for blind children. They were asked to explore freely a series of 8 incomplete raised-line drawings in order to identify as quickly and accurately as possible what the drawing represented and which element was missing. In order to familiarize children with the task, two additional raised-line drawings were used for practice. Children were allowed up to 2 min of exploration per picture and one answer (i.e., including both object and missing element) per trial. Prior to the presentation of each picture, the category name of the depicted object was given to the participants (e.g., instrument for item 7) (see [8] for a similar procedure). We selected this option because pre-tests without semantic cues revealed floor performance in children. During the test, no feed-back was given, regardless of the nature of the response.
3 Results Children’s responses fall into 4 possible categories: I. Object and element (participants identified both the object and the missing element); II. Object only (participants could only identified the object); III. Element only (participants could only identify the missing element); IV. None (participants could neither identify the object nor its missing element). Table 1. Responses distribution in percent for each group (all items together).
The results (see Table 1) indicated that, when both groups were taken together, responses from category IV predominated (47.65%), followed by responses from category I (32.65%). However, the response distribution varied clearly according to group. The dominant response of the sighted children was failure to identify both the object and the missing element (category IV: 58.7%). By contrast, the visually impaired children succeeded frequently at the task (category I: 42.3%), at least far more than the sighted children did (category I: 23%). For both groups, responses from category II occurred quite often (16.85%), whereas responses from category III were very
rare (2.85%). This meant that part of the children were able to name the object without identifying the missing element. By contrast, children rarely identified the missing element only. When we calculated a recognition score (0-8 points, with 0.5 point per picture when children found the expected name of the object, plus 0.5 point for the missing element), we found significant between-group difference with the visually impaired children scoring higher (M = 4.23, SD = 1.98) than the sighted children (M = 2.50, SD = 1.54), Mann-Whitney U-test, p = 0.0333. When we look at the distribution of responses for each item separately (see Fig. 1), we observed a large variation in responses across items. Three different patterns emerged. In pattern 1, children’s responses were fairly distributed among the 4 categories: this pattern concerned Item 1 (Girl), and Item 6 (Sweater). The distribution of responses did not vary significantly according to group for these two items (Girl: Fisher exact test, p = 0.687; Sweater: Fisher exact test, p = 0.474). In pattern 2, children’s dominant response was failure to identify both the object and the missing element: this pattern concerned Item 2 (Hand), Item 3 (Comb), and Item 4 (Scissors). For these three items, the failure rate was high in participants (69.5% for Hand, 73% for Comb, and 61.5% for Scissors). The distribution of responses did not vary significantly according to group for Item 2 (Hand: Fisher exact test, p = 0.719), and Item 3 (Comb: Fisher exact test, p = 0.573). However, for Item 4 (Scissors), the distribution of responses varied significantly according to group (Fisher exact test, p = 0.010): failure to identify both the object and its missing element was the dominant response of the sighted children, but not that of the visually impaired children who could, for part of them, identify the object as scissors. Finally, in pattern 3, children’s dominant response was success to identify both the object and the missing element: this pattern concerned Item 5 (Ladder), Item 7 (Guitar), and Item 8 (Clock). For these three items, the identification rates were quite great in participants (50% for Ladder and Guitar, and 53.8% for Clock). The distribution of responses varied significantly according to group for Item 5 (Ladder: Fisher exact test, p = 0.048), and Item 7 (Guitar: Fisher exact test, p = 0.011), but not for Item 8 (Clock: Fisher exact test, p = 0.532). For Items 5 and 7, success to identify both the object and element was the dominant response of the visually impaired children, but not that of the sighted children who mainly failed to identify the object and its missing element.
4 Conclusion Three main findings emerged from the study. First, success at identifying incomplete raised-line pictures through haptics (naming object plus missing feature) concerned 32.65% of children’s responses, suggesting that the task was hard although not entirely impossible (see [8]). Interestingly, part of the children was able to identify the object without the missing feature, but the reverse quite never occurred. In line with our hypothesis, these findings suggest that a disruption (missing feature) in the configural properties of a stimulus (raised-line drawing) did not hinder the haptic processing and recognition of that stimulus in terms of object representation. It is likely that children paid attention to local and small size units when exploring the raised-line configura-
tions; they may have guessed what a given picture could depict in terms of object representation, before they were able to identify the missing element through further analytical examination of the stimulus (see also [5]). To what extent children who succeeded at the task constructed an internal representation of raised-line pictures which integrated local parts into a coherent whole is however unknown, and may call for further investigations. Second, we found that overall the visually impaired children outperformed the sighted controls at the incomplete picture identification task. This finding confirms the overall superiority of visually impaired children over their sighted peers in haptic picture perception tasks (see [6], [7], [10]), and extents this observation to the haptic processing of incomplete pictures. Third, we found large variations in children’s responses to incomplete pictures across items, and observed that the superiority of the visually impaired children over their sighted peers was not systematic, as it depended on the item to be processed. In conclusion, findings from this study lead us to suggest that adapting materials from the Wechsler’ image completion subtest to the haptic modality may be relevant to investigate haptic perceptual reasoning in children with and without visual impairments. The development and/or adaptation of tests for visually impaired children is still a challenge, as only a limited number of psychometric tools are currently available (see e.g., [11] and [12] for a review). However, because the task was rather difficult, even for the visually impaired children, it would be worth completing these experimental results with scores obtained by older participants (sighted and visually impaired) in order to demonstrate that the task can be achieved with a rather good level of performance at the end of childhood. The next step of our research project therefore consists in collecting data with a larger sample of participants, including children, adolescents, and young adults, with and without visual impairment. Moreover, as suggested by several authors [13-14], it might be necessary to proceed to separate standardizations in order to take the diversity inherent to the visually impaired people into account (associated disorders, visual status, individual's visual experience…).
Acknowledgments This work was supported in part by a grant from the PRES of Toulouse and Région Midi-Pyrénées attributed to the first author for her PhD Thesis. We thank Mélanie Labardin, Cival-Lestrade Centre, Sandra Mesnières, Alfred Peyrelongue Centre, and the children who took part in the study.
References 1. Berger, C., Hatwell, Y.: Dimensional and Overall Similarity Classification in Haptics: A Developmental Study. Cog. Dev. 8, 495-516 (1993) 2. Lederman, S.J., Klatzky, R.L.: Haptic Perception: A Tutorial. Atten. Percept. Psychophys. 71, 1439-1459 (2009) 3. Hatwell, Y., Streri, A., Gentaz, E.: Touching for Knowing. Philadelphia PA. John Benjamins Publishing Compagny (2003)
4. Wechsler, D.: WISC-IV, Echelle d’Intelligence de Wechsler pour Enfants et Adolescents. Paris. ECPA (2005) 5. Puspitawati, I., Jebrane, A., Vinter, A.: Local and Global Processing in Blind and Sighted Children in a Naming and Drawing Task. Child Dev. (in press) 6. D’Angiulli, A., Kennedy, J.M., Heller, M.A.: Blind Children Recognizing Tactile Pictures Respond like Sighted Children given Guidance in Exploration. Scand. J. Psychol. 39, 187190 (1998) 7. Pathak, K., Pring, L.: Tactual Picture Recognition in Congenitally Blind and Sighted Children. Appl. Cog. Psychol. 3, 337-350 (1989) 8. Heller, M. A., Calcaterra, J. A., Burson, L. L., Tyler, L. A.: Tactual Picture Identification by Blind and Sighted People: Effects of Providing Categorical Information. Perception & Psychophysics 58, 310-323 (1996) 9. Picard, D., Lebaz, S.: Identifying Raised-Line Pictures by Touch: A Hard-but not Impossible-Task. J. Vis. Impair. Blind. 106, 427-431 (2012) 10. Vinter, A., Fernandez, V., Orlandi, O., Morgan, P.: Exploratory Procedures of Tactile Images in Visually Impaired and Blindfolded Sighted Children: How they Relate to their Consequent Performance in Drawing. Res. Dev. Disabil. 33, 1819-1831 (2012) 11. Ballesteros, S., Bardisa, D., Millar, S., Reales, J. M.: The Haptic Test Battery: A New Instrument to Test Tactual Abilities in Blind and Visually Impaired and Sighted Children. Brit. J. Vis. Impair. 23, 11-24 (2005) 12. Mazella, A., Albaret, J-M., Picard, D.: Haptic Tests for Use with Children and Adults with Visual Impairment: A Literature Review. J. Vis. Impair. Blind. (in press) 13. Bonnardel, R., Baton, C., Thiebaut, E.: Test d’Intelligence Pratique pour Déficients Visuels: B101DV. Talant. Les Doigts Qui Revent (2010) 14. Dekker, R.: Visually Impaired Children and Haptic Intelligence Test Scores: Intelligence Test for Visually Impaired Children (ITVIC). Dev. Med. & Child Neurol. 35, 478-489 (1993)
