Sound to Meaning Mappings in the Bouba-Kiki Effect
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Sound to Meaning Mappings in the Bouba-Kiki Effect Kelly McCormick ([email protected]) Department of Psychology, 36 Eagle Row Emory University, Atlanta, GA 30322 USA Jee Young Kim ([email protected]) Department of Psychology, 36 Eagle Row Emory University, Atlanta, GA 30322 USA Sara List ([email protected]) Neuroscience Program Graduate Division of Biological and Biomedical Sciences, 1462 Clifton Road Emory University, Atlanta, GA 30322 USA Lynne C. Nygaard ([email protected]) Department of Psychology, 36 Eagle Row Emory University, Atlanta, GA 30322 USA Abstract systematically related to the meanings they represent? Research has found that certain classes of sounds are more Sound to meaning correspondences in spoken language are assumed to be largely arbitrary. However, research has likely than others to appear in words with particular identified a number of exceptions to the arbitrariness meanings and that language users are sensitive to these non- assumption. In particular, non-arbitrary mappings between arbitrary sound to meaning mappings. Cross-linguistic sound and shape, the bouba/kiki effect, have been research has identified systematic sound-to-meaning documented across diverse languages and both children and mappings in terms describing a range of perceptual adults are sensitive to this type of sound symbolic mapping. experiences such as brightness/lightness (Hirata & Kita, The cognitive basis for the associations between nonword labels and particular shapes remains poorly understood 2011; Kunihira, 1971), texture (Dingemanse, 2011; Kita, making it difficult to predict how findings generalize beyond 1997; Magnus, 2001), and size (Nuckolls, 1999; Ultan, the limited stimuli tested. To identify systematic bases for 1978). For example, across many languages vowels with sound-to-shape mappings, we collected ratings of higher frequency components (such as /i/) tend to be roundedness and pointedness for a large database of associated with small/diminutive concepts, whereas vowels pseudowords. We find that attributes of both consonants and with lower frequency components (such as /a/) tend to be vowels are systematically related to judged shape meanings used to represent large or augmentative concepts (Nuckolls, of pseudowords, and offer hypotheses as to the cognitive mechanisms underlying the observed patterns. 1999; Ultan, 1978). Further, listeners appear to be sensitive to these regularities in spoken language and reliably apply Keywords: Sound symbolism; Language; Bouba-Kiki Effect; these mappings when inferring meanings of unfamiliar Multisensory Representation words (Mondloch & Maurer, 2004; Sapir, 1929; Spector & Maurer, 2008; Thompson & Estes, 2011). A central question in the cognition of language is how Perhaps one of the most studied examples of non- sounds in language encode and convey meaning. Sound-to- arbitrariness, coined the ‘bouba-kiki effect’, involves the meaning mappings in language are believed to be largely reliable matching of nonsensical names to abstract shapes. arbitrary, with sounds in words bearing no inherent Although the specific labels and shapes employed in the relationship to the objects, actions, and events in the world task have varied from study to study, the basic finding is that they represent (Gasser, 2004; Monaghan, Christiansen, that in a forced-choice task people consistently match labels & Fitneva, 2011; Saussure, 1916). In such a system words such as kiki and takete to angular/pointed shapes and match come to represent meanings by learned associations, and in labels such as bouba and maluma to rounded/amoeboid principle, any meaning could be represented by any shapes (Köhler, 1929; Ramachandran & Hubbard, 2001). combination of the finite inventory of sounds in a given Robust mappings between certain nonsense words and language. Arbitrary reference is considered powerful object shapes have been demonstrated across a variety of because symbolic forms are unconstrained in relation to languages and cultures, with reported matching rates meaning, supporting referential flexibility (Gasser, 2004; ranging from approximately 80-95% of respondents Monaghan & Christiansen, 2005). (Bremner et al., 2013; Davis, 1961; Köhler, 1929). These But is the sound structure of language completely are unfamiliar nonsense words and novel shapes, with which independent of meaning or are certain speech sounds the individual does not have prior experience, yet stable in bouba-kiki tasks or for which there was a clear possible associations emerge across individuals. basis for mapping. For example, stimuli containing What makes some sounds more fit than others for unvoiced stop consonants are preferentially mapped to representing certain meanings? Although there is pointed shapes (Bremner et al., 2013; Fort et al., 2014; widespread documentation of the bouba-kiki effect across Köhler, 1929; Nielsen & Rendall, 2011; Ramachandran & languages, cultures, and development, the phenomenon is Hubbard, 2003; Westbury, 2005). In contrast, sonorants not well understood (see Nielsen and Rendall, 2011). In the emerge as a class of sounds that are preferentially mapped present study, we seek to identify acoustic and phonetic to bloblike or amoeboid shapes (Fort et al., 2014; Köhler, patterns in this particular sound to meaning mapping and 1929; Ramachandran & Hubbard, 2003; Westbury, 2005). work to explain how certain attributes of the linguistic As an intermediate category between stops (which are signal might serve to bring online mental representations of completely obstructed when produced) and sonorants meaning. (which are completely unobstructed), we included fricative and affricate phonemes. Parise and Spence (Parise & Experiment Spence, 2009, 2012) found that tones composed of square The aim of this study is to identify acoustic and phonemic waves (and which have a noisy quality) were associated correlates to meaning, and posit cognitive mechanisms with a more pointed visual object as compared to tones underlying these sensory-conceptual mappings. We composed of sinusoidal waves (which have a smoother tonal examined the specific relationship between the sound quality), which were associated with the more bloblike structure of language and meanings related to visuo-haptic shape. With respect to roundedness or pointedness of properties of objects. To assess language users’ mappings various vowels, research comparing speakers of English and between pseudowords and rounded and pointed meaning, Czech showed that both groups reliably matched /i/ (as in we conducted three behavioral rating experiments including neat) to a triangular shape and /u/ (as in mood) to an one forced-choice task and two likert rating tasks, collecting elliptical shape (Tarte & Barritt, 1971; Tarte, 1974). In an ratings on 570 nonsense words on dimensions of implicit association experiment, Parise and Spence (2012) roundedness or pointedness. Numerous studies examining found that perceivers associate relatively high pitch tones the bouba-kiki effect have found associations between with more acutely pointed shapes and relatively lower pitch specific speech sounds and visuo-haptic object properties. tones with more obtusely pointed shapes. However, previous research on sound to shape mappings In addition to systematically sampling the acoustic and has generally employed a very limited number of phonemic space, we also varied the way in which we pseudowords (but see Fort, Martin, & Peperkamp, 2014), assessed sound to meaning mappings. Previous research on most famously takete and kiki (which are mapped to pointed the bouba-kiki phenomenon has relied heavily on two- shapes) and maluma, and bouba (mapped to bloblike alternative forced choice tasks. Although these studies shapes). Although these studies report high rates of provide robust evidence that certain sounds are reliability in matching tasks, they offer little in the way of preferentially matched to particular meanings, they do not an explanation of the phenomenon. To evaluate the necessarily capture richer, more nuanced information about contribution of various properties of spoken language, we these mappings. By using likert-type rating tasks in addition build on previous research by systematically sampling the to typical forced-choice tasks, we included a measure that phonetic and acoustic space of reliable sound to shape was able to capture graded phenomena. mappings. To this end, we constructed a database of English-like pseudowords from several classes of speech Method sounds. The resulting permutations of phonemic combinations allowed us to examine how particular sound Participants properties are mapped to meaning. Participants were 65 members of the Emory University We examined speech sounds that varied in manner of community. All participants were native speakers of articulation, including stops, sonorants, and fricatives, and English, with normal hearing and no reported history of voicing. Each consonant class included voiced and voiceless speech/language impairments. 34 participants participated in sounds with the exception of sonorants, which only exist in the two-alternative forced-choice task, and 31 participants voiced form. The sonorants in our set consist of both nasals participated in the likert-type rating task. and liquids, the obstruents consist of affricates, fricatives and stop consonants. We combined these classes of Materials consonants with different vowel types, rounded and Stimuli consisted of audio recordings of 570 pseudowords. unrounded, in order to study