Child Neuropsychology, 2015 Vol. 21, No. 1, 90–105, http://dx.doi.org/10.1080/09297049.2013.876492

Environmental sound recognition by timbre in children with Williams syndrome Pastora Martínez-Castilla1, Mª Ángeles García-Nogales1, Ruth Campos2, and Manuel Rodríguez1 1

Department of Developmental and Educational Psychology, Faculty of Psychology, Universidad Nacional de Educación a Distancia, Madrid, Spain 2 Department of Basic Psychology, Universidad Autónoma de Madrid, Madrid, Spain Anecdotal reports have described children with Williams syndrome (WS) as presenting outstanding skills for recognizing environmental sounds by their timbre. This has led to suggest that the skills for environmental sound recognition by timbre are highly developed in WS. Furthermore, the term hypertimbria has been proposed to refer to this feature. However, no academic research has assessed these skills in WS. This study therefore aimed to contrast the reports on the highly developed skills for environmental sound recognition by timbre in children with WS. An environmental sound recognition task was administered to children with WS, children with Down syndrome of the same chronological age and cognitive level, and chronological age-matched typically developing children. Participants with WS performed significantly lower than their typically developing peers and no significant differences were found between the WS and Down syndrome groups. Unlike previous reports, this study points out that in WS environmental sound recognition by timbre does not constitute a phenotypic strength either in absolute or relative terms. Results suggest that children with WS do not present hypertimbria or preserved skills for timbre recognition. We discuss the implications of these results for theories of cognitive modularity. Keywords: Williams syndrome; Environmental sound recognition; Timbre; Phenotypic profile; Modularity.

Williams syndrome (WS) is a neurodevelopmental disorder occurring in 1:20,000 to 7500 live births (Morris, Demsey, Leonard, Dilts, & Blackburn, 1988; Strømme, Bjørnstad, & Ramstad, 2002). It is caused by a hemizygous deletion in 7q11.23 (Ewart et al., 1993). In addition to mild-to-severe intellectual disability, individuals with WS present an uneven cognitive profile (e.g., Bellugi, Wang, & Jernigan, 1994; Mervis, Morris, Bertrand, & Robinson, 1999). Whereas language, face-processing, and auditory rote memory function This research was partially funded by grant AP2003-5098 from the Ministry of Education and Science of the Spanish Government. The manuscript was proofread thanks to funds from the Department of Basic Psychology (Universidad Autónoma de Madrid). We would like to thank all the parents and participants who collaborated in this research. Address correspondence to Pastora Martínez-Castilla, Department of Developmental and Educational Psychology, Universidad Nacional de Educación a Distancia, C/Juan del Rosal, no 10, 28040 Madrid, Spain. E-mail: [email protected]

© 2014 Taylor & Francis

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relatively well, visuospatial construction, planning, and number skills are more severely impaired (e.g., Bellugi, Lichtenberger, Jones, Lai, & George, 2000; Mervis et al., 2000). The first descriptions of this uneven profile led to consider WS evidence of innate cognitive and brain modularity (e.g., Pinker, 1991). Since then, much interest and debate has given rise on this topic (e.g., Karmiloff-Smith, 1998; Karmiloff-Smith, Brown, Grice, & Paterson, 2003). Thus, other researchers have claimed that nativist perspectives should be replaced by a neuroconstructivist approach when studying neurodevelopmental disorders such as WS (e.g., Karmiloff-Smith, 2009). From this approach, the cognitive profile of individuals with WS is considered to stem from the interaction of genes, brain, cognition, and environment, instead of resulting from innate specification (Karmiloff-Smith, 2009). Yet, music skills in individuals with WS have often been described as innate and considered an independent functioning module (e.g., Lenhoff, Perales, & Hickok, 2001a, 2001b; Levitin & Bellugi, 1998). Thus, it has been reported that, despite their intellectual disability, individuals with WS present preserved, relatively preserved, or outstanding music skills, and this has been taken as support for views of cognitive modularity (Lenhoff et al., 2001a; Levitin & Bellugi, 1998, 2006). Remarkably, pitch and rhythm discrimination and the perception of expressive phrasing and melodic elaboration have been found in WS at the level of typically developing (TD) individuals of the same chronological age (CA) (Hopyan, Dennis, Weksberg, & Cytrynbaum, 2001; Levitin, 2005; Levitin & Bellugi, 2006). Moreover, in WS, the incidence of absolute pitch, a rare musical ability that consists of being able to identify musical pitch without a reference tone (e.g., Takeuchi & Hulse, 1993), has been considered to be ten times higher than that found in TD individuals (Lenhoff et al., 2001a, 2001b). However, other studies have found conflicting results regarding the musical skills of individuals with WS. Their pitch discrimination abilities have been reported to be significantly lower than those of TD peers matched for CA (Hopyan et al., 2001; Martens, Reutens, & Wilson, 2010). In rhythm discrimination tasks, individuals with WS have been found to perform significantly lower than TD individuals of the same CA (Hopyan et al., 2001; Martínez-Castilla, Sotillo, & Campos, 2011) or of the same mental age (Don, Schellenberg, & Rourke, 1999). Singing accuracy problems and a global integration deficit for melodic processing have also been reported in WS (Deruelle, Schön, Rondan, & Mancini, 2005; Elsabbagh, Cohen, & Karmiloff-Smith, 2010; Martínez-Castilla & Sotillo, 2008). Additionally, recent data suggest that the incidence of absolute pitch is not higher in WS than in the TD population (Martínez-Castilla, Sotillo, & Campos, 2013). These results have called into question the view that music skills in WS can be considered evidence of modularity (e.g., Hopyan et al., 2001; MartínezCastilla et al., 2011, 2013) and have underlined the possibility that music processing in WS may be atypical (e.g., Deruelle et al., 2005; Elsabbagh et al., 2010). Despite the controversy over musical skills in WS, regarding the auditory profile of this population, there seems to be consensus that individuals with WS present an unusual sensitivity for sounds (e.g., Gothelf, Farber, Raveh, Apter, & Attias, 2006; Klein, Armstrong, Greer, & Brown, 1990; Levitin, Cole, Lincoln, & Bellugi, 2005). Thus, hyperacusis, or hypersensitivity to sounds, occurs in 75–100% of the WS population (e.g., Don et al., 1999; Gothelf et al., 2006; Klein et al., 1990; Martin, Snodgrass, & Cohen, 1984). The prevalence of hyperacusis is not only higher than that reported for TD individuals but is also significantly higher than the prevalence of hyperacusis found in individuals with autism spectrum disorders or Down syndrome (DS) (Levitin et al., 2005).

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Although far from being clear, the origins of hyperacusis in WS have been linked to alterations of the cochlear efferent system (Attias, Raveh, Ben-Naftali, Zarchi, & Gothelf, 2008; Barozzi et al., 2012). Additionally, hyperacusis in WS has been related to nonauditory factors, such as fears and anxiety (Blomberg, Rosander, & Andersson, 2006) and seems to be independent of hearing thresholds (Elsabbagh, Cohen, Cohen, Rosen, & Karmiloff-Smith, 2011; Klein et al., 1990). It should be noted that hyperacusis is a complex phenomenon that may refer to four different auditory symptoms: the ability to detect sounds that are too soft for others, a lower pain threshold for loud sounds (i.e., odynacusis), fear or phobia regarding sounds that are not usually found to be aversive, and attraction or fascination with certain sounds (Levitin et al., 2005). Data collected from parental reports have shown that hyperacusis in WS mainly refers to being bothered or frightened by certain sounds (Don et al., 1999; Gothelf et al., 2006; Klein et al., 1990). Aversive sounds for individuals with WS may subsequently become auditory fascinations (e.g., vacuum cleaners) (Levitin et al., 2005). Related to both the musical skills and hyperacusis of individuals with WS, anecdotal reports have emphasized these individuals’ outstanding ability to recognize environmental sounds by their timbre (Klein et al., 1990; Levitin, 2005; Levitin & Bellugi, 1998). Compared with TD individuals and individuals with DS or autism spectrum disorders, these reports seem to be specific to WS (Levitin et al., 2004, 2005). An environmental sound can be defined as a sound that has meaning by virtue of a causal relationship with the event that produces the sound, that is, as a sound that has a real event as its source and that therefore specifies this event in the environment (e.g., Ballas & Howard, 1987; Lemaitre, Houix, Misdariis, & Susini, 2010). Environmental sounds carry out an important functional role by conveying meaningful information for the listener (Ballas, 1993; Coward & Stevens, 2004; Cumming, Čeponienė, Dick, Saygin, & Townsend, 2008). Thus, sound source and event recognition is a primary task of the auditory system that is enabled by the acoustic properties of an environmental sound, that is, by its timbre (Coward & Stevens, 2004; Gaver, 1993; Lemaitre et al., 2010; McAdams & Drake, 2002). Therefore, timbre is the attribute of an auditory signal that allows two sounds to be distinguished or that allows the sound source to be identified (e.g., Lemaitre et al., 2010). In WS, timbre perception in environmental sounds has been considered a phenotypic marker of auditory and musical function (Levitin & Bellugi, 2006). As aforementioned, individuals with WS have been reported to present highly developed skills in recognizing environmental sounds by their timbre (Levitin & Bellugi, 1998). For example, many individuals with WS seem to be able to accurately recognize different models of vacuum cleaners and cars by the sound of their motor (Levitin, 2005; Levitin & Bellugi, 1998; Levitin et al., 2005). These skills for environmental sound recognition by timbre have been linked to the musical phenotype of individuals with WS (Levitin & Bellugi, 1998, 2006). It has been suggested that these identification skills along the continuum of timbre may be similar to the skills involved in absolute pitch along the continuum of pitch (Levitin & Bellugi, 1998). Accordingly, the term “hypertimbria” has been proposed as a descriptor of timbre perception in WS (Levitin & Bellugi, 1998). As claimed for other auditory abilities in this population (e.g., absolute pitch), highly developed skills in recognizing environmental sounds by timbre along with general cognitive deficits may lead to suggestions of cognitive

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modularity. Thus, as part of musical ability, it has been suggested that timbre perception may be preserved in individuals with WS (Levitin & Bellugi, 1998). However, despite the body of anecdotal reports on the highly developed skills for environmental sound recognition by timbre in WS, thus far no academic study has evaluated these claims. There has been, instead, one study that has assessed timbre discrimination skills in this population. Levitin and Bellugi (2006) recorded the sound of 12 different vacuum cleaners and presented pairs of these sounds to individuals with WS and to musically trained TD individuals matched for CA. Participants were asked to discriminate whether the two sounds in each pair were the same or different. No significant differences were found between the performances of the groups. These results suggest that timbre or environmental sound perception in WS constitutes an area of strength in absolute terms; that is, an area in which individuals with WS perform on par with TD individuals of the same CA (Levitin & Bellugi, 2006). Considering the paucity of research on environmental sound perception in individuals with WS and, specifically, the lack of research on their environmental sound recognition skills by timbre, the current study sought to extend knowledge on this topic. We assessed the abilities of children with WS to use timbre to recognize the causal events or sources of different environmental sounds to evaluate the reports of their remarkable abilities for environmental sound recognition (Levitin, 2005; Levitin & Bellugi, 1998; Levitin et al., 2004, 2005). Therefore, the study aimed to contrast such reports by assessing whether the recognition of environmental sounds by timbre in WS is highly developed and can be considered a phenotypic strength either in absolute or relative terms. To test whether environmental sound recognition by timbre is an absolute strength in WS, a group of children with WS and a group of CA-matched TD peers were compared in their performance on an environmental sound recognition task. If, as suggested by previous reports (e.g., Levitin & Bellugi, 1998, 2006), children with WS presented hypertimbria or highly developed skills for environmental sound recognition being this area an absolute strength, the results of the WS group would not be significantly lower than those of the TD participants matched for CA. But, even if the results of the WS group were lower than those of the CA-matched TD group, the skills of children with WS for recognizing environmental sounds could still constitute a phenotypic strength in relative terms. As usual in the literature (e.g., Bellugi et al., 2000), to test this possibility, the performance of children with WS was also compared with the performance of children with DS of the same CA and cognitive level. Similar to individuals with WS, individuals with DS have intellectual disability (e.g., Connolly, 1978; Gigson, 1978). However, unlike the former group, individuals with DS do not present outstanding abilities for environmental sound recognition (Levitin et al., 2004, 2005). Thus, their skills in identifying environmental sounds by timbre are in line with their cognitive level (Marcell, Busby, Mansker, & Whelan, 1998). In addition, musical skills, such as those for melodic reproduction, are significantly lower in individuals with DS compared to those with WS (Levitin, 2005). Additionally, in contrast to WS, hyperacusis is a rare phenomenon in DS (Levitin et al., 2005). Therefore, if environmental sound recognition by timbre were in WS an area of strength in relative terms, children with WS would perform significantly higher than children with DS. On the contrary, lack of significant differences between the WS and DS groups would provide strong evidence that environmental sound recognition cannot be considered a phenotypic strength in WS.

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METHODS Participants The sample was composed of three groups of 15 children with WS (aged 8.42–16.83 years), 15 children with DS (aged 7.42–15.75 years), and 30 TD children (aged 8–16.92 years). The number of participants with WS was as large as or larger than that of other published studies on their auditory and music skills or on other areas of their phenotype (e.g., Hopyan et al., 2001; Lacroix, Guidetti, Rogé, & Reilly, 2009; Lenhoff et al., 2001a; Levitin & Bellugi, 1998). Yet, the number of participants in the TD group was enlarged in order to increase the power of the study (Tabachnick & Fidell, 2007). To allow for conclusions as to whether environmental sound recognition by timbre in WS can be described as an area of strength in absolute terms (one of the aims of the study), as established in the literature (e.g., Karmiloff-Smith et al., 2003), the children with WS and the TD participants were matched for CA (p = .99). To test whether the skills of children with WS for recognizing environmental sounds by timbre can be considered a phenotypic strength in relative terms, a group of children with DS was also included in the study. Participants with DS were matched on CA (p = .99) to the WS group. Children with DS and TD participants did not differ significantly in CA either (p = .48). The Wechsler Intelligence Scale for Children (WISC) was used to assess participants’ cognitive level. Children with WS and the TD group were assessed with the WISC-IV (Wechsler, 2005). Data from children with DS were collected earlier and thus assessments were carried out with the WISC (Wechsler, 1985). The range and mean of intelligence measurements in the WS and DS groups were consistent with the data from the literature in this respect (e.g., Chapman & y Hesketh, 2000; Martens, Wilson, & Reutens, 2008). No significant differences were found between participants with WS and participants with DS for fullscale IQ (p = .97), verbal IQ (p = .70), and performance IQ (p = .39) and thus their cognitive level was equivalent. However, the three intelligence quotients were significantly lower in children with WS and children with DS compared to their TD peers (p < .001 for all comparisons). Table 1 shows the descriptive characteristics of the WS, DS, and TD groups. Participants with WS were recruited through a National Williams Syndrome Association, participants with DS were recruited through special education schools, and the TD children were recruited through mainstream schools. All participants with WS presented the clinical features of the WS phenotype (e.g., Bellugi et al., 2000) and had a positive fluorescent in situ hybridization (FISH) test to confirm gene deletion and the WS diagnosis. All participants with DS had confirmed trisomy 21 without mosaicism. As

Table 1 Descriptive Characteristics of the WS, DS, and TD Groups.

n Gender (M/F) Mean CA Full-Scale IQ Verbal IQ Performance IQ

WS group

DS group

TD group

15 7/8 13.31 (2.76) 49 (5.79) 61.47 (9.09) 51.33 (7.05)

15 8/7 12.38 (2.97) 45.67 (7.89) 56.73 (10.37) 48.27 (5.39)

30 17/13 13.66 (2.83) 116.93 (10.91) 116.80 (11.61) 109.03 (11.06)

Note. Values in parentheses represent standard deviations.

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reported by parents or teachers, no participants had any other clinical diagnoses or suffered from hearing or visual impairment. No participant had received prior musical training. Because the incidence of hyperacusis is low or very low in TD individuals and in individuals with DS (Blomberg et al., 2006; Levitin et al., 2005) but is reported to be high in WS (e.g., Gothelf et al., 2006; Klein et al., 1990; Martin et al., 1984), as in previous research (Elsabbagh et al., 2011), hyperacusis was only assessed in participants with WS. For this purpose, the parents of children with WS were administered a version of the hyperacusis questionnaire (Don et al., 1999; Klein et al., 1990). Fourteen of the 15 participants with WS were reported by their parents to be very sensitive, bothered by or afraid of certain sounds (those previously described in the literature in this respect, Levitin et al., 2005: e.g., fireworks, engines, thunders, and balloon popping) and therefore were considered to have hyperacusis.

Task and Procedure To our knowledge, there exists no standardized test for evaluating environmental sound recognition by timbre suitable for children with intellectual and developmental disabilities. Therefore, a task was created for this study. To design the task, we first reviewed the literature on environmental sound perception in individuals with neurodevelopmental disorders. Although there is paucity of research on the topic, previous studies have assessed the skills for recognizing environmental sounds by their timbre in individuals with intellectual and developmental disabilities of different etiologies, including those with DS (Boucher, Lewis, & Collis, 2000; Hobson, Ouston, & Lee, 1988; Lamberts, 1980; Van Lancker et al., 1988). In such studies, a set of photos (four or more) and an environmental sound were simultaneously or nonsimultaneously presented to participants, who then were required to select the photo matching the sound. This methodological approach has proved useful and suitable to evaluate environmental sound recognition in children with intellectual and developmental disabilities and therefore we followed the same approach to design the task of this study. Even so, to minimize the demands and general cognitive load of the task, in the current research, the photos and the environmental sound were simultaneously presented, and only three photos (instead of four or more) were administered.1 Three photos were preferred over two photos to reduce the probability of chance scoring. To choose the experimental stimuli, we considered the following criteria. First, the stimuli should be chosen from sounds frequently used in the literature on timbre perception (e.g., Ballas, 1993; Lemaitre et al., 2010; Marcell, Malatanos, Leahy, & Comeaux, 2007). Second, the environmental sounds should not cause sensitivity, fascination, aversion, or pain to individuals with WS (Levitin et al., 2005). Finally, the sounds should have previously proved suitable for evaluating environmental sound recognition in 1

It should also be noted that the same task structure (i.e., requiring participants to choose from three or more visual items the one that matches an auditory stimulus) has been broadly used in the literature to evaluate different areas of the phenotype of individuals with WS or DS. This can be exemplified when considering the large number of studies in which the tests Peabody Picture Vocabulary Test-Revised (Dunn & Dunn, 1981) and Test for Reception of Grammar (TROG: Bishop, 1989, or TROG-2; Bishop, 2003) have been used in these populations (e.g., Bellugi et al., 1994; Mervis & John, 2010). This ensures that the structure of the task designed for the current research was not too complex and demanding for the children with WS and DS who participated in this study.

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neurodevelopmental disorders (e.g., Hobson et al., 1988; Lamberts, 1980). Fulfilling the three criteria was deemed important to increase the validity of the study and to avoid possible biases related to the characteristics of the WS and DS groups. The water and “walking” sounds included in Hobson et al.’s (1988) study fulfilled these criteria and thus were chosen as experimental stimuli. Specifically, the stimuli consisted of five kinds of water (the sea, a shower, a fountain, a waterfall, a river) and five kinds of walking (running downstairs, walking on shingle, walking on pavement, walking on rubble, running on pavement). Auditory stimuli were recorded ad hoc for this study. The auditory stimuli lasted between 9 and 13 s. Color photos of each experimental stimulus were taken and used as visual stimuli for the study. The environmental sound recognition task was composed of 10 items (one for each experimental stimulus). For each item, participants were first shown three photos. Then, while the photos were still present, the environmental sound was played. Participants were asked to select the photo that matched the presented sound. The three photos administered to participants were the target (photo matching the sound, i.e., source of the sound) and two foils. The foils and the target belonged to the same category (water or walking). The photos were presented in random order. Before running the study, the task was pretested in 20 TD adults to ensure that the stimuli were easily identifiable. An accuracy of 100% was found. After the pretest, the three groups of the study were administered the environmental sound recognition task. Participants were assessed individually. To ensure that participants were familiar with all experimental items, they were shown the photos and asked to provide a label or description for them. No participant had difficulty identifying any of the photos representing the events that were to be evaluated and no participant reported being bothered by, afraid of or fascinated by the sounds presented in the experimental task. Participants with WS were assessed in a quiet room at their home. Participants with DS and the TD participants were assessed in a quiet room at their schools. The environmental sounds were presented via loudspeakers at a comfortable listening level. To check that the volume levels were appropriate, prior to the administration of the environmental sound recognition task, participants were presented with other auditory items (e.g., music). While performing the experimental task, no participant complained or covered their ears as a sign of uncomfortable volume and no participant reported being bothered by, afraid of or fascinated by the sounds presented in the experimental task. For participants with WS, this was further confirmed with their parents’ answers on the hyperacusis questionnaire. Statistical analyses were performed with SPSS 15.0.

RESULTS The total number of correct responses was calculated for each group. The results are shown in Table 2. As can be seen in Table 2, on a descriptive level, the TD children achieved the highest performance, followed by the WS group and the DS group. Table 2 Mean Scores (SD) on the Environmental Sound Recognition Task.

Number of correct responses

WS group

DS group

TD group

7.4 (2.2)

6.53 (2.03)

9.03 (0.93)

Note. Values in parentheses represent standard deviations.

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Furthermore, unlike the WS and DS groups, the TD children performed nearly at ceiling. Consequently, the standard deviation in the TD group was lower than that of the WS and DS groups. As previously explained, in the task, within each of the 10 items, there were three possible responses and only one was right. Therefore, the task was composed of 10 dichotomous items (i.e., 0 or 1 as possible scores) and, in each of them, the probability of succeeding by chance was 0.33. In order to check whether task scoring was at chance level, we calculated the minimum number of correct responses that participants had to produce for ensuring task performance at a level higher than chance. Following the Binomial distribution with parameters n (number of dichotomous items) and Π (probability of success) and a confidence level of 95%, performance was significantly above chance when scoring 5 or more. As shown in Table 2, the three groups of the study performed above chance. Figure 1 shows the boxplots with the distribution of scores in each group. As can be seen in this figure, no floor or ceiling effects were found in the WS and DS groups. As aforementioned, the TD group scored near ceiling. To assess whether differences in results between groups were significant, a one-way analysis of variance (ANOVA) was conducted with group (WS group, DS group, TD group) as a between-subjects factor. There was a significant effect of group on performance on the environmental sound recognition task, F(2, 57) = 13.22, p < .001, η2 = .32. Games-Howell post hoc tests were conducted to compare groups of participants with each

10 9 8 7

Score

6 5 4 3 2 1 0 WS

DS

TD

Group Figure 1 Boxplots with the distribution of scores in each group.

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other. Children with WS scored significantly lower than their TD peers, p = .035, 95% CI [–3.16, –.11]. However, no significant differences were found between the WS group and the DS group, p > .05, 95% CI [–1.05, 2.78]. Participants with DS performed significantly lower than the TD group, p = .001, 95% CI [–3.91, –1.09]. To evaluate whether participants’ CA was related to their skills for environmental sound recognition and thus whether these skills change with CA, correlations between these two variables were calculated separately for each group. No significant correlations were found for any of the groups (p > .05). DISCUSSION This study aimed to assess whether, as suggested by previous reports (Klein et al., 1990; Levitin, 2005; Levitin & Bellugi, 1998; Levitin et al., 2004, 2005), individuals with WS present outstanding skills for environmental sound recognition and whether such skills can be considered a phenotypic strength in absolute or relative terms. Participants with WS performed on the environmental sound recognition task significantly lower than their TD peers matched for CA. Therefore, these results suggest that environmental sound recognition in WS is not an absolute strength. Furthermore, when the children with WS were compared with children with DS of the same CA and IQ in their performance on the experimental task, no significant differences were found. This finding suggests that the skills for environmental sound recognition in children with WS cannot be considered a relative strength either. Both the WS and DS groups performed on the task above chance level and no floor or ceiling effects were found in any of these groups. This rules out that the task were too demanding or not sensitive enough for the assessment of children with WS. Therefore, the lower performance of this group in comparison with the TD group and the lack of significant differences between the WS and DS groups were not due to such problems. It should also be noted that, as previously mentioned, the procedure used in the task designed for this study (i.e., choosing between different visual alternatives the one corresponding to an auditory presented item) is a well-attested assessment procedure broadly used in the literature on WS or DS (e.g., Bellugi et al., 1994; Mervis & John, 2010). This ensures that the requirements of the task at the level of decision and probe recognition processes were not too high for the WS and DS groups. Furthermore, the attentional and working memory load of the task was minimal and thus lower than that used in previous studies carried out with individuals with intellectual and developmental disabilities (Boucher et al., 2000; Hobson et al., 1988; Lamberts, 1980; Van Lancker et al., 1988) since the environmental sound was simultaneously administered with the photos and only three (instead of four or more) visual items were presented. All these arguments show that the results found in the study cannot be accounted for by methodological artifacts related to the task (i.e., lack of sensitivity and high demands of the task). As explained above, the task was suitable for the assessment of environmental sound recognition in children with WS or DS. In contrast to previous claims (Levitin & Bellugi, 1998), the results of this study therefore suggest that children with WS do not have highly developed skills for environmental sound recognition by timbre. The term hypertimbria was proposed by Levitin and Bellugi (1998) to refer to the timbre recognition ability in WS. As explained in the “Introduction,” by using this term, Levitin and Bellugi suggested that individuals with WS present skills for recognizing timbre that would be equivalent to the skills involved in

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absolute pitch. Possessors of absolute pitch are able to identify discrete stimuli along the continuum of pitch. Individuals with hypertimbria would be able to perform similarly in the continuum of timbre. Recent research has shown that, in contrast to initial reports (Lenhoff et al., 2001a, 2001b), individuals with WS do not possess absolute pitch (Martínez-Castilla et al., 2013). The current study suggests that children with WS do not have what has been referred to as hypertimbria either. The reports on the outstanding abilities for environmental sound recognition by timbre of individuals with WS in the face of their intellectual disability have led to suggest that timbre perception is preserved in this population (Levitin & Bellugi, 1998). In WS, the same claims referred to other auditory abilities (e.g., absolute pitch) have been used to argue that these abilities function independently of other cognitive systems (Lenhoff et al., 2001a; Levitin & Bellugi, 1998). Our results would not support such views of cognitive modularity. Thus, this study suggests that timbre perception is not preserved in WS. The ability of individuals with WS to recognize environmental sounds has been related to their sensitivity to sounds or hyperacusis (Klein et al., 1990; Levitin et al., 2005). Thus, it may be that sensitivity to sound leads to enhanced timbre perception. In this study, all participants with WS except for 1 were described by their parents as having hyperacusis. However, their performance on the environmental sound recognition task was significantly lower than that of the TD participants and was at the same level as performance of children with DS. Therefore, this study suggests that hyperacusis in WS does not necessarily involve high timbre recognition skills. The results of this study are not consistent with those found by Levitin and Bellugi (2006), who reported that individuals with WS present environmental sound discrimination skills that are at the same level as those of TD individuals matched for CA. The differences in the results may be explained by the different nature of the tasks used in the two studies. Whereas Levitin and Bellugi employed a discrimination task, we used a recognition task. Claims about the highly developed skills of children with WS for timbre perception have been based on anecdotal reports regarding their proficiency to recognize environmental sounds (Levitin & Bellugi, 1998). The aim of the article was to evaluate these claims. Therefore, a recognition task was employed in this study. Additionally, a recognition task was preferred over a discrimination task because the former focuses on the experience of everyday listening, which involves not only focusing on an acoustic signal but also identifying events and sources of sounds through this signal (Gaver, 1993). Hence, a discrimination task would have only required participants to focus on the qualities of the auditory input. Instead, the environmental sound recognition task employed in this study allowed us to assess the skills of children with WS to use timbre to identify the causal events or sources of different environmental sounds and, therefore, to evaluate their everyday listening skills to extract relevant information about the environment from sound. Thus, through sound recognition processes, listening contributes to the appropriate behaviors that we need to adopt with respect to the environment (McAdams & Drake, 2002). Yet, it may be the case that the timbre discrimination skills of individuals with WS were higher than their recognition skills by timbre. Nevertheless, it should be considered that if individuals with WS presented what has been referred to as hypertimbria, they would show not only high performance on timbre discrimination but also high skills for timbre recognition. Thus, the different results of this research and Levitin and Bellugi’s (2006) study could rather be explained by considering the differences in the experimental stimuli of the

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two studies. Levitin and Bellugi used stimuli that cause fascination in some individuals with WS, that is, the sound of different vacuum cleaners (Levitin et al., 2005). However, as explained in the “Method” section, we used everyday sounds that were not considered fascinating by participants with WS (Levitin et al., 2005). In TD individuals, research comparing expert and nonexpert listeners (e.g., musicians vs. nonmusicians) has shown that environmental sound or timbre perception is enhanced if listeners are presented with stimuli from their field of expertise (e.g., Lemaitre et al., 2010). Following an approach of progressive specialization of cognitive functions (Mareschal et al., 2007), fascination with certain sounds may lead to becoming an expert at such sounds. Consequently, the fascination that some individuals with WS feel for the stimuli presented by Levitin and Bellugi could have led participants with WS to achieve high results on the discrimination task. Similar phenomena have been reported for other fields of the cognitive profile in WS. Thus, although initial studies reported rich and unusual vocabularies in WS (e.g., Bellugi, Bihrle, Neville, Jernigan, & Doherty, 1992), further research has shown that this is only the case when individuals with WS talk about their topics of interest (Stojanovik & van Ewijk, 2008). Importantly, this account highlights how experimental data that may be taken as support for views of innate cognitive modularity —as it has often been the case for WS—may instead be explained from a neuroconstructivist approach (KarmiloffSmith, 2009; Mareschal et al., 2007). As aforementioned, individuals with DS have been reported to show neither outstanding musical ability nor hyperacusis (Levitin, 2005; Levitin et al., 2004, 2005). More importantly for this study, they have not been found to present remarkable environmental sound recognition skills (Marcell et al., 1998). Therefore, following reports on the accuracy of individuals with WS in recognizing environmental sounds (e.g., Klein et al., 1990; Levitin & Bellugi, 1998), higher results would have been expected in the WS group compared to the DS group. However, participants with WS and those with DS did not differ significantly in their performance on the environmental sound recognition task. This result would provide stronger evidence that environmental sound perception by timbre should not be considered a phenotypic strength in WS. Comparisons based on anecdotal reports among TD individuals, individuals with DS, and those with WS have led to suggest that accurate skills for timbre recognition are specific to the latter (Levitin et al., 2004, 2005). In contrast, this study shows not only that the skills for environmental sound recognition by timbre in children with WS are at the same level as the skills of children with DS but also that such skills in both groups are significantly lower than those presented by TD children of the same CA. Nevertheless, it should be noted that a lack of significant differences between the results of the WS and DS groups does not mean that the processes underlying task performance are the same in both groups. Furthermore, as shown for other cognitive fields (Karmiloff-Smith, 1998), the results of individuals with WS or DS on the environmental sound recognition task may be achieved by auditory processes different than those employed by TD individuals. Thus, global versus local auditory processing has been found to be atypical in WS (Deruelle et al., 2005; Elsabbagh et al., 2010). In addition, individuals with WS show different patterns of neural activation for auditory stimuli. Unlike TD individuals, a wider network, including the amygdala, cerebellum, brainstem, and visual cortex, is activated in individuals with WS (Levitin et al., 2003; Thornton-Wells et al., 2010). With regard to DS, research has shown accelerated auditory processing at the level of the brainstem but delayed cortical responses to auditory stimuli (Díaz & Zurron, 1995; Pekkonen, Osipova, Sauna-Ahoa, & Arvio, 2007; Seidl et al., 1997). Atypical patterns of lateralization in auditory processing have also been

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found in individuals with DS (Groen, Alku, & Bishop, 2008). Given that auditory processing seems to be atypical in both individuals with WS and individuals with DS, further research should study the processes underlying environmental sound perception in these individuals. In this study, no significant correlations were found in any of the groups between performance on the environmental sound recognition task and CA. For the TD group, near-toceiling effects hinder the interpretation of this result. For the WS and DS groups, the lack of significant correlations suggests that, during the age range included in the study, no changes related to CA occur to the skills for environmental sound recognition. Thus, based on this research, no solid conclusions can be drawn about the development of such skills in WS. Future studies should evaluate the developmental trajectories (Thomas et al., 2009) of environmental sound recognition by timbre in children with WS earlier in their ontogenesis. Due to strict criteria for auditory stimuli selection, a small set of environmental sounds was used in this research. Consequently, the environmental sound recognition assessment was not comprehensive and this limits the study. In addition, the sample size of the WS group was relatively small. Although frequent in the literature on WS because of the low incidence of the syndrome, this problem is also a limitation of the study. Further research should therefore assess the recognition of a larger number of sound categories in larger samples of individuals with WS. Thus, results of the current study should be viewed with a degree of caution and may therefore be considered preliminary. Yet, considering the lack of studies on the skills of children with WS for recognizing environmental sounds by timbre despite the large number of anecdotal reports on the topic, our research paves the way for future work and means an important step forward in the field. The results of this study not only contribute to a better definition of the WS phenotype but also to the theoretical debate of cognitive modularity in WS, as previously discussed. In summary, to date, there have been only anecdotal reports on the skills for environmental sound recognition by timbre in individuals with WS. To our knowledge, this is the first study designed to evaluate the claims stated in these reports. Unlike previously suggested (Levitin & Bellugi, 1998), this study points out that, either in absolute or relative terms, environmental sound recognition does not constitute a phenotypic strength in the WS cognitive profile. Individuals with WS do not seem to present hypertimbria or preserved skills for timbre recognition. The results of this study suggest that children with WS do not have environmental sound recognition skills on par with TD children matched for CA; rather, they have skills at the level of children with DS of the same CA and cognitive level. Original manuscript received July 16, 2013 Revised manuscript accepted December 12, 2013 First published online January 16, 2014

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