Systematic Influence of Perceived Grasp Shape on Speech Production

Abstract

Previous research has shown that precision and power grip performance is consistently influenced by simultaneous articulation. For example, power grip responses are performed relatively fast with the open-back vowel [a], whereas precision grip responses are performed relatively fast with the close-front vowel [i]. In the present study, the participants were presented with a picture of a hand shaped to the precision or power grip. They were required to pronounce speech sounds according to the front/above perspective of the hand. The results showed that not only the grip performance is affected by simultaneously pronouncing the speech sound but also the production of speech sound can be affected by viewing an image of a grip. The precision grip stimulus triggered relatively rapid production of the front-close vowel [i]. In contrast, the effect related to the power grip stimulus was mostly linked to the vertical dimension of the pronounced vowel since this stimulus triggered relatively rapid production of the back-open vowel [a] and back-mid-open vowel [o] while production of the back-close vowel [u] was not influenced by it. The fact that production of the dorsal consonant [k] or coronal consonant [t] were not influenced by these stimuli suggests that the effect was not associated with a relative front-back tongue shape of the articulation in the absence of changes in any vertical articulatory components. These findings provide evidence for an intimate interaction between certain articulatory gestures and grip types, suggesting that an overlapping visuomotor network operates for planning articulatory gestures and grasp actions.

The Sound of Grasp Affordances: Influence of Grasp‐Related Size of Categorized Objects on Vocalization

“…The general view is that voiced consonants might be linked to larger objects than unvoiced consonants (Newman, ; Thompson & Estes, ). Moreover, the current findings are in line with the study reported by Vainio, Rantala, et al (), which similarly did not find any influence of the viewed grip type on the pronunciation of [t] and [k], while the pronunciation of [i] and [ɑ] was significantly influenced by these stimuli. Hence, it appears that articulation processes responsible for the increasing/decreasing of the vocal cavity and lip opening for vowel production are more sensitive to influences of size‐grasp affordances than those articulation processes related to tongue shaping for consonants production.…”

“…Furthermore, this effect is in line with previous observations showing that production of the precision and power grips is planned in the motor networks that overlap with the processes related to articulation of the vowel [i] and [ɑ], respectively (Tiainen, Tiippana, et al, ; Vainio et al, ). In addition, this finding is also in line with our previous observations showing that viewing a picture of a hand shaped to the precision or power grip does not only facilitate corresponding grasp responses (Vainio, Tucker, & Ellis, ), but it can also facilitate vocal responses of the vowel [i] and [ɑ], respectively (Vainio, Rantala, et al, ). Hence, it appears that observing the precision grip or an object whose size‐grasp affordance is congruent with the precision grip can potentiate articulation of the vowel [i].…”

“…Errors (i.e., the participant uttered the wrong speech unit or did not produce any response) and RTs more than two standard deviations from each participant's condition means were excluded from the reaction time analysis . It is noteworthy that a 2 SD cutoff procedure is a valid and frequently used statistical tool (Singh, ) that we have previously used in all our studies that have measured reaction times of manual and vocal responses (e.g., Tiainen, Lukavský, et al, ; Vainio, Rantala, et al, ; Vainio et al, ; Vainio, Tiainen, et al, ). Of the trials, 2% were removed as errors and 4.4% were removed as outliers.…”

“…We obtained a written informed consent from all participants. The selection of number of participants (20/21) was based on the previous similar investigation of the influence of perceived grip type on vocalizing the vowels [i] and [ɑ], which showed significant effects using less than 20 participants (Vainio, Rantala, et al, ). Our sample size calculations, carried out by using G*power software, were based on the results of that study [i.e., a significant interaction between Grip and Response ( = 0.564) in Experiment 1].…”

“…In the final block, they were required to pronounce the syllable [te] if the object was natural and the vowel [ke] if it was manufactured (Mapping 2 for the consonant block). Although regarding the consonant blocks, we were interested in exploring potential interaction between consonant production and the size of the categorized object, the participants were asked to pronounce CV syllables because this has been the task also in all out previous studies (e.g., Vainio, Rantala, et al, ; Vainio et al, ). Participants typically find it particularly difficult to pronounce these consonants in absence of any vowels.…”