Morsella, E., & Krauss, R. M. (2005). Muscular activity in the arm during lexical retrieval: Implications for gesture-speech theories. Journal of Psycholinguistic Research. 34(4), 415-427. Retrieved from SpringerLink on 7 March 2008.
In this article, 6 electromyographic (EMG) electrodes were attached to the forearm muscles of 30 Columbia University students (14 males and 16 females), measuring muscular activity to see if lexical gestures+, were used when explaining certain types of words more than others. Morsella and Krauss used EMG so that more subtle arm movements could be detected. Participants were given the definitions of 17 abstract, and 19 concrete, low-frequency nouns, which had been previously rated by 42 other undergraduates*, and were asked to name the word which had been described. So that they would not attend to their arm movements, participants were told the purpose of the study was to measure memory and stress.
This study found that greater EMG amplitudes were found during retrieval of concrete words than abstract words, t (29) = 2.76, p<.01. Concrete and spatial scores of the nouns accounted for 0.27 of EMG amplitude variance. To explain overt gestural movement, the experimenters theorize that concrete nouns offer elements which can be expressed visually, which is much more difficult (if possible) for abstract nouns. To account for subtler movements, Morsella and Krauss cite the Gestural feedback model (GFM), which they expound upon in their own 2004 article. The GFM theorizes that lexical gestures help to hold feature information in a semantic-motor loop long enough for word retrieval, much the way vocal rehearsal keeps auditory information activated in the phonological loop. Put simply, these gestures help to communicate concepts that can be explained by visual features (concrete nouns) and aids in the retrieval of words in general.
+ As opposed to conventionalized or rhythmic gestures. The authors cite Krauss et al. (1996) for a review of gesture types:
Krauss, R. M., Chen Y., Chawla, P. (1996). Nonverbal behavior and nonverbal communication: What do conversational hand gestures tell us? Advances in Experimental SocialPsychology, 28, 389â??450.
* 20 males and 22 females were asked to rate how spatial, concrete, active, pantomimable, familiar, drawable, manipulable, and valuable each noun was, along a 6-point continuum.
In response to Professor Knupsky's comment, I wanted to add some excerpts from the study of how the authors defined "lexical gestures."
"Lexical gestures are spontaneous, complex, articulate hand-arm movements that seem related to the ideational content of the speech they accompany. They are ubiquitous. A person speaking about a corkscrew, for example, may make a rapid, twisting hand motion, or outline a circular space with both hands when referring to a birthday cake. It is important to distinguish these gestures from symbolic gestures or emblems, which are hand-arm signs with conventionalized meanings (e.g., the â??thumbs-upâ?? sign), and from motor
gestures or beats, which are brief, repetitive co-speech movements that are roughly coordinated with speech prosody (McClave, 1994), but seem unrelated to the semantic content"
(p. 415-416)
"Signals resulting from activity unrelated to the tasks â?? e.g., scratching, adjusting clothing, fiddling with the electrodes, tapping (motor gestures), or activity resulting from reading the definitions â?? were noted on the EMG chart and excluded from the data analysis" (p. 419)
And Professor Knupsky's point is a very good one...using a lexical gestures reminds me of playing charades, where your task is not only to act out concepts in a way that make the most sense to you, but to act them out in a way that is most likely to make sense to your audience. Also, as these gestures are part of speech, they are part of its rhythm.