Hand Preference in Adults’ Referential Gestures during Storytelling: Testing for Effects of Bilingualism, Language Ability, Sex and Age
Round 1
Reviewer 1 Report
The idea of your study is interesting, my recommendations are the following:
Lines 90-102 and 102-106; 332-340 mentioned a bibliographic index in the press, these articles are not accepted, I recommend rewriting the sentences and deleting the index 42 from the paragraphs.
At the end of sections 1.1., 1.2, 1.3 and 1.4 mention what you predict, and then in section 1.5 the same hypotheses are repeated. Also mention as the first hypothesis and then continue with the second purpose. I recommend clarification and do not duplicate the information.
Lines 143-146 is not clear, I recommend clarification.
Author Response
Reference number 42 is now published so we have updated the reference so that readers can now see it is publicly available and have left the citations in the text.
We are not entirely sure we understand this comment: "At the end of sections 1.1., 1.2, 1.3 and 1.4 mention what you predict, and then in section 1.5 the same hypotheses are repeated. Also mention as the first hypothesis and then continue with the second purpose. I recommend clarification and do not duplicate the information.". We have highlighted in blue now at the end of sections 1.1, 1.2, 1.3, 1.4 so that readers can see that we explicitly articulate our predictions. We have left the repetition of these predictions in section 1.5 because, while the wording is repetitive, the function of section 1.5 is to contextualize those predictions in light of the objectives of this study.
We have reworded lines 143-146. Hopefully that point is clearer now.
Reviewer 2 Report
This study used an existing data set (in which participants told back the stories in two “Pink Panther” clips to an apparently naïve listener) to examine the hypothesis that the production of hand gestures accompanying speech is left-(brain)-lateralized and, hence, predominantly right handed, and also to consider whether it is closely linked to language lateralizatin. Partly to address this latter question, it also looked at four potential determinants of hand gesture lateralization that are known to affect language lateralization – bilingualism, language proficiency, sex, and age.
Overall, there were significantly more right-handed gestures than left-handed gestures (about 60:40). There were no significant effects of bilingualism or language proficiency. The participants included English monolinguals, French monolinguals, and English-French bilinguals (some with English L1 and some with French). The bilinguals were tested in both languages. In English, male speakers produced more right-handed gestures than female speakers, and there was a tendency for older speakers to produce fewer right-handed gestures (and hence to be closer to a 50:50 ratio – though detailed information about ratios is not given). In French, there were no effects of age or sex (though numerically males produced more right-handed gestures, and the sample size was smaller than for English). The result are not, therefore, suggestive of the idea that gesture lateralization is closely linked to language lateralization. The authors suggest three other potential determinants of gesture lateralization, but they do not have data relating to them – lateralization of handedness in tool use (or manipulation objects more generally), (specific to the current task) the tendency to focus of the right side of the screen when watching video material, and aiding lexical access.
This paper is clearly written. It’s conclusions are somewhat inconclusive (!) and a least one of the participant groups is rather small (French monolinguals). It presents data on hand gestures than could be of interest, so if it fits the remit of Symmetry, it could be published in that journal.
Minor Points
It might be rather a complex issue, but a comment on the difference between the 60:40 ratio reported here, and the standard figures of language lateralization, which are more extreme, might be interesting.
I find the term “bilateral lateralization” misleading, because it isn’t lateralization
Author Response
We have added in the discussion a comparison to the degree of right-handedness in the population (80%). We inserted this at the point we thought it made the most sense in our argument.
We have replaced "lateralization" with "processing" wherever we previously used "bilateral lateralization".
Reviewer 3 Report
This is a nice idea that refers to a large body of previous studies exploring the links between co-speech gestures and lateralization
The differences between the groups were too big, particularly the small group of French speakers (age difference - need to be analyzed as covaraites). The lack of handedness measure is problematic. On the other hand, the lack of differences between mono and bilinguals perhaps suggests that the other language should have been a reversed orientation language (such as Arabic for example). The second clip was always described after the first clip, therefore could rely more heavily of long term memory retrieval. Perhaps a separate analysis of the gestures per clip might reveal different lateralization patterns? Language requires editing - missing verbs for example as in this sentence "The two language sessions for the bilinguals on two different days, usually about a week apart."Author Response
We agree with the reviewer that we did not have enough French monolinguals to reach any firm conclusions about RHP in that population. We have stated that this is a limitation of our study in the discussion.
Our main analytic approach in this study was a regression, precisely to control for possible colinearities of the predictor variables.
We were intrigued by the reviewer's suggestion that hand-preference might have changed over the course of the retelling. Unfortunately, many participants produced so few gestures over the course of the entire retelling that we do not have reliable data to compare the two cartoons. We will keep this idea in mind for our future research.
We have added the missing verb in the sentence identified by the reviewer and reread the manuscript for grammar, correcting any errors we identified. We may still have missed some and welcome the chance to correct any we may have missed.
