Attitudes toward everyday odors for children with visual impairments: a pilot study.
Odors (Physiological aspects)
Vision disorders (Complications and side effects)
|Publication:||Name: Journal of Visual Impairment & Blindness Publisher: American Foundation for the Blind Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2010 American Foundation for the Blind ISSN: 0145-482X|
|Issue:||Date: Jan, 2010 Source Volume: 104 Source Issue: 1|
|Topic:||Event Code: 310 Science & research Canadian Subject Form: Odours; Odours|
|Geographic:||Geographic Scope: France Geographic Code: 4EUFR France|
The question of how the processing of stimuli from the external
world is organized or reorganized when a sensory modality is altered or
missing has been the subject of numerous studies, although the studies
have mostly been on tactile and auditory abilities (Hatwell, 2003). In
contrast, olfaction has been poorly investigated in people who are
visually impaired, despite the increasing evidence that humans have a
keen sense of smell (Schaal & Porter, 1991). Odors influence mood;
well-being (Ehrlichman & Bastone, 1992); and social interactions,
such as the choice of partners (Herz & Inzlicht, 2002). Emotional
and social implications of odors go back to the earliest periods of
development (Schaal, 1988). Olfaction should thus be considered a
significant source of environmental information and emotions in persons
with visual impairments.
Most, if not all, studies of the relationship between olfaction and blindness aimed to test the intuitive hypothesis of increased sensitivity of the unimpaired senses (for a review, see Ferdenzi, Holley, & Schaal, 2004). The comparison of olfactory detection thresholds in participants with and without visual impairments first led to inconsistent results (Boccuzzi, 1962; Griesbach, 1899). More recent studies that have used more reliable methods found no difference between the two groups in olfactory sensitivity, discrimination, or cued identification (that is, the choice of the name of an odor from among several alternatives) (Diekmann, Walger, & von-Wedel, 1994; Schwenn, Hundorf, Moll, Pitz, & Mann, 2002; Smith, Doty, Burlingame, & McKeown, 1993).
Conversely, more ecological perceptual tasks, such as noncued odor identification, revealed better performances by participants with visual impairments (Murphy & Cain, 1986; Rosenbluth, Grossman, & Kaitz, 2000; Wakefield, Homewood, & Taylor, 2004). This advantage was interpreted as reflecting higher attention to olfactory stimuli, resulting in deeper knowledge and the better ability to reactivate associated information. Thus, possible differences in favor of people with visual impairments may be a result more of advantages in attentional strategies than of enhanced sensitivity. This view was advocated by Tilney (1929), who examined Helen Keller: "[Her] olfactory sense shows nothing above the normal average.... Her sensory supremacy is entirely in the realm of intellect" (pp. 1242, 1254).
Outstanding olfactory abilities of individuals with visual impairments have repeatedly been reported in everyday life contexts. For instance, Julia Brace (James, 1890) and an anonymous young boy (Hinds, 1984) were able to sort the freshly washed linen of acquaintances by smell alone; Willetta Huggins was able to identify the color of fabrics according to the odor of the dyes (Gault, 1923). Describing children with visual impairments sniffing out objects, people, or themselves, Hinds (1984) interpreted these frequent behaviors as an unrestrained seeking of information. Odors seem to help build representations of the environment, as Rosenfeld (2001) also suggested. In Rosenfeld's survey, respondents with visual impairments declared more often than their sighted counterparts that odors provide useful information to characterize or identify places and people. These sparse observations stimulated us to investigate olfaction-blindness interactions in everyday settings.
The purpose of our study was to conduct a pilot investigation of the self-reported awareness and reactivity to odors of children with visual impairments and sighted children. A questionnaire related to relevant everyday contexts involving food and social cues, as well as the general environment, was used to determine whether, and in which conditions, odors would constitute salient cues for children with visual impairments.
Six boys and two girls with visual impairments, aged 8 to 11, were recruited from a specialized center in Dijon, France (see Table 1 for the characteristics of the participants). None of them had any detected associated disorder. The children were matched for age and gender with eight sighted children, who were selected from a larger group who were recruited in leisure centers. Both experimental groups were unaware that their answers would be compared. Three children from each group were from families whose parents smoked. The participants did not report any olfactory dysfunction. Before the experiment began, the directors of the centers gave authorization to conduct the study, the children's caregivers gave informed written consent, and the children provided oral assent. The study complied with the Declaration of Helsinki guidelines on human experimentation.
Variables and procedure
The participants reported various behaviors and attitudes toward odors on the basis of a 26-item questionnaire (Ferdenzi, 2007; available from the first author). This questionnaire was developed to compensate for the absence of a tool to evaluate nonpathological olfactory behaviors in children. The questions were aimed at gauging active seeking, awareness, and affective reactions triggered by food, social, or more general environmental contexts involving odors, such as the following: "When your mother is cooking, do you go to smell what she is preparing? .... Do you think that people without perfume have a natural odor?" and "Are there odors that you like smelling when you feel sad?" The answers were scored on a 3-point scale (0, 0.5, or 1) and summed to form a total score ranging from 0 to 26. The questionnaire was administered individually in 30-minute sessions by a female interviewer in a quiet room. The participants were ensured that their answers would be strictly confidential (for details of the procedure, see Ferdenzi, Coureaud, Camos, & Schaal, 2008).
The total scores for the questionnaire on olfactory behaviors were significantly higher for the children who were visually impaired than for the sighted children (mean [+ or -] SD = 11.1 [+ or -] 2.6 versus 8.9 [+ or -] 1.6, paired t-test: [t.sub.7] = 2.89, p < .05). The children with visual impairments also had higher scores on 18 out of 26 items, a proportion that is significantly higher than the one expected from an equal probability of either group to be more oriented toward odors (binomial test, p < .05).
The higher scores of the children with visual impairments were especially observed for items that were related to social odors, that is, odors that naturally emanate from or are associated with people's bodies (Schaal & Porter, 1991). The children reported more frequently that people, in general, emit a natural odor (average individual item score = .81 [+ or -] .26 versus .50 [+ or -] .38 for the children who were sighted) and that they would be disturbed if someone who smelled bad would sit near them (.75 [+ or -] .27 versus .50 [+ or -] .27). They also declared more often that they sought to smell their own odor on their clothes (.38 [+ or -] .35 versus .19 [+ or -] .26) or directly on their bodies (.25 [+ or -] .38 versus .06 [+ or -] .18) and that they would mind if they could not smell the odor of their parents and siblings any more (.50 [+ or -] .46 versus .31 [+ or -] .37). In addition, the participants with visual impairments more often treasured objects (such as flowers, perfumed objects or toys, and incense) because of their smell (.44 [+ or -] .18 versus .19 [+ or -] .26). They were better able to mention an event recalled by a smell (.38 [+ or -] .44 versus .13 [+ or -] .23), and they more often stated that they paid attention to odors in situations involving unknown foods (.63 [+ or -] .44 versus .44 [+ or -] .42) or disliked foods (.44 [+ or -] .32 versus .25 [+ or -] .27). Notably, they smelled food less often than did the sighted children during meals outside the home (.19 [+ or -] .37 versus .38 [+ or -] .44) but more often during meals at home (.44 [+ or -] .18 versus .25 [+ or -] .38).
Using a questionnaire on everyday olfactory behaviors, which is an alternative method to those that were previously used in psychophysical studies of the links between olfaction and blindness, this study found that the children with visual impairments reported that they paid more attention and reacted more often to odors than did the children who were sighted. They scored higher on a majority of items, especially those related to social and food odors. Although these results are preliminary, they provide a hint to encourage parents and teachers to pay more attention to the tendency of children with visual impairments to attend to odors in everyday life.
Items related to social odors of self and others elicited the largest differences between the sighted children and those who were visually impaired. First, there is an informative advantage to this increased attention to social odors. The smells of people present detectable differences that are related to identity, age, gender, hygiene, physical activity, emotional state, and illness (Chen & Haviland-Jones, 2000; Schaal & Porter, 1991). Being aware of such cues gives the children privileged access to information that is usually provided by vision. Such information may contribute to the evaluation of the physical and behavioral features of an interactant (see also Rosenfeld, 2001). It also has utility in the development of self-regulatory behavior for the control of hygiene (see Shih & Chang, 2005, for the olfactory control of dental hygiene). The second advantage of increased attention to social odors is the positive emotional impact of the odors. The odors of parents and the children themselves are known to provide comfort to children (Ferdenzi et al., 2008). Therefore, although further research is needed to gain a better understanding of why children with visual impairments spontaneously allocate greater attention to social odors, educational support of this tendency could be beneficial.
Items related to food contexts also differentiated the children with visual impairments from the sighted children, whether unknown and disliked or familiar foods were involved. Difficulties with feeding behavior are indeed prevalent in children with visual impairments, leading to delays in feeding skills (Brody & Webber, 1994) and to maladjusted intake (Thommessen, Trygg, Riis, & Kase, 1989). Appropriate sensory training for food odors and aromas could thus help increase the children's expertise in a range of food stimuli and, hence, reduce their unpredictability, which is one cause of the difficulty. Such an odor-based education could promote the pleasure of eating or, at least, direct attention to the pleasurable aspects of food when other aspects (texture and convenience) are potentially repelling. It is interesting that the present data indicated that the children with visual impairments tended to repress their sniffing behaviors in public, attesting to social pressure that depreciates such behaviors (Brown, Hobson, Lee, & Stevenson, 1997; Hinds, 1984; Le Gutrer, 2002). Such behaviors reflect the strong need for pertinent information to enhance knowledge of subtle aspects of oneself, others, and the environment (Hinds, 1984). Therefore, parents and teachers need to show more consideration of these behaviors and to guide them rather than prohibit them.
In this study, only odors from the proximal (social, food) environment differentiated the children with visual impairments from the sighted children. At the studied age range, the children with visual impairments did not seem to have developed a specific attention to odors related to places in the wider environment. Since odors, such as those emanating from shops (like pharmacies, bakeries, and flower shops) contribute to spatial awareness of one's location (Kitchin, Blades, & Golledge, 1997), it is likely that these types of odors become meaningful as children grow older and acquire autonomous movement. In any case, a smell-based pedagogy at home and at school could improve the development of these essential orientation skills in integrating smells, along with other information, as qualifying or confirmatory indications.
The authors gratefully acknowledge the parents and children for welcoming our research, as well as the directors of the Clos Chauveau and of the Maisons des Jeunes et de la Culture (Gresilles, Maladiere, and Montchapet) in Dijon, France.
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Camille Ferdenzi, Ph.D., postdoctoral research assistant, Swiss Center for Affective Sciences, University of Geneva, 7 rue des Battoirs, CH 1205, Geneva, Switzerland; e-mail:
Table 1 Characteristics of the participants with visual impairments. Age (in years) Gender Snellen visual acuity 8 Male 20/200 8 Female No vision 9 Male 20/200 10 Male 20/200 (right) 20/100 (left) 10 Male 20/80 10 Female 20/100 (right) 20/80 (left) 11 Male <20/1200 (right) no vision (left) 11 Male 20/400 Age (in years) Etiology 8 Albinism (congenital) 8 Congenital blindness 9 Myopia, nystagmus (congenital) 10 Albinism (congenital) 10 Eye albinism (congenital) 10 Cataract, nystagmus (congenital) 11 Optic atrophy (congenital) 11 Stargardt's disease (diagnosed at 8 years old)
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