An Investigation of Sound-Symbolism in the Context of Tactile Feeling

Crossmodal associations between naturally occurring tactile and sound textures

This study investigates the crossmodal associations between naturally occurring sound textures and tactile textures. Previous research has demonstrated the association between low-level sensory features of sound and touch, as well as higher-level, cognitively mediated associations involving language, emotions, and metaphors. However, stimuli like textures, which are found in both modalities have received less attention. In this study, we conducted two experiments: a free association task and a two alternate forced choice task using everyday tactile textures and sound textures selected from natural sound categories. The results revealed consistent crossmodal associations reported by participants between the textures of the two modalities. They tended to associate more sound textures (e.g., wood shavings and sandpaper) with tactile surfaces that were rated as harder, rougher, and intermediate on the sticky-slippery scale. While some participants based the auditory-tactile association on sensory features, others made the associations based on semantic relationships, co-occurrence in nature, and emotional mediation. Interestingly, the statistical features of the sound textures (mean, variance, kurtosis, power, autocorrelation, and correlation) did not show significant correlations with the crossmodal associations, indicating a higher-level association. This study provides insights into auditory-tactile associations by highlighting the role of sensory and emotional (or cognitive) factors in prompting these associations.

Selectively manipulating softness perception of materials through sound symbolism

Cross-modal interactions between auditory and haptic perception manifest themselves in language, such as sound symbolic words: crunch, splash, and creak. Several studies have shown strong associations between sound symbolic words, shapes (e.g., Bouba/Kiki effect), and materials. Here, we identified these material associations in Turkish sound symbolic words and then tested for their effect on softness perception. First, we used a rating task in a semantic differentiation method to extract the perceived softness dimensions from words and materials. We then tested whether Turkish onomatopoeic words can be used to manipulate the perceived softness of everyday materials such as honey, silk, or sand across different dimensions of softness. In the first preliminary study, we used 40 material videos and 29 adjectives in a rating task with a semantic differentiation method to extract the main softness dimensions. A principal component analysis revealed seven softness components, including Deformability, Viscosity, Surface Softness, and Granularity, in line with the literature. The second preliminary study used 27 onomatopoeic words and 21 adjectives in the same rating task. Again, the findings aligned with the literature, revealing dimensions such as Viscosity, Granularity, and Surface Softness. However, no factors related to Deformability were found due to the absence of sound symbolic words in this category. Next, we paired the onomatopoeic words and material videos based on their associations with each softness dimension. We conducted a new rating task, synchronously presenting material videos and spoken onomatopoeic words. We hypothesized that congruent word-video pairs would produce significantly higher ratings for dimension-related adjectives, while incongruent word-video pairs would decrease these ratings, and the ratings of unrelated adjectives would remain the same. Our results revealed that onomatopoeic words selectively alter the perceived material qualities, providing evidence and insight into the cross-modality of perceived softness.

Visual-auditory interactions on explicit and implicit information processing

Interactions among sensory information are important for generating a coherent percept of the external world. Facilitation and inhibition effects in cross-modal perception have been widely studied for decades. The present study tried to confirm the interaction effects between sensory information in a bimodal context and explore these influences when part of the sensory information was presented without participants' subjective awareness. A total of 40 undergraduate participants were recruited in this mixed design study. Participants were required to count the flashing of the black circle (visual task) or the presentation frequency of the beep sound (auditory task) with the presence of either congruent or incongruent sensory signals in the background. Participants in the explicit group generally performed more accurately and also faster with the congruent stimuli than with the incongruent stimuli. Performance accuracy in the visual task in the implicit group was affected by the non-target sound signals which were presented beneath participants' subjective awareness. The better performance yielded in the auditory task than in the visual task was explained by the appropriateness of the auditory stimulation to the task nature. In addition, the supportive findings regarding processing without awareness should be interpreted with caution.