Title: Bimodal language switching and single-task/dual-task switching: a bimodal advantage?
(ENGLISH/ASL as necessary)
Abstract: There is increasing interest in multimodality, including bimodal (signed-spoken)
bilingualism. Language-switching experiments have been used to study bilinguals, and these
studies, testing sequential unimodal (spoken-spoken) language switching, have found longer
reaction times (RTs) and higher error rates in switch trials than repeat trials. These ‘switch costs’
have been replicated often (Kiesel et al. 2010). Bimodal bilinguals often produce ‘code-blends’, in
which elements of the signed and spoken languages appear simultaneously, which is possible
because the languages do not share a primary articulator (e.g. Emmorey et al. 2008).
Experiment 1 examined modality effects in language switching. Participants (N=16) were hearing
native speakers of German who had completed 7-9 semesters of German Sign Language (DGS)
classes and had learned English in school. There were two conditions: unimodal (German-English
switching) and bimodal (German-DGS switching). For vocal RTs (comparing only the German
vocal responses across conditions due to differences in timing across modalities), we conducted a
Modality×Shift ANOVA. There was a significant main effect of Modality, p<.001, and Shift,
p<.01; the interaction between Modality and Shift was also significant, p<.05. The results indicate
that vocal responses are generally faster in bimodal switching blocks than in unimodal blocks,
indicating a bimodal switching advantage.
Experiment 2 examined simultaneous bimodal language production with a dual-task design (e.g.
Navon & Miller 1987), comparing dual-task trials with single-task trials in order to determine
whether there is a dual-task advantage for bimodal production. Studies comparing dual-task and
single-task responses across two non-language modalities often find dual-tasks costs (e.g.
Huestegge & Koch 2009). However, bimodal bilinguals often produce words and signs
simultaneously rather than switching, so we may expect a different pattern for these tasks.
Participants (N=12) were hearing native speakers of German who completed 7-9 semesters of DGS.
We compared RTs across Task-Type (single-task or dual-task) with a Task-Type×Shift ANOVA.
For German responses, we found a significant main effect of Task-Type, p<.001, and Shift, p<.01,
but the interaction between Task-Type and Shift did not reach significance, p>.05. For DGS manual
responses, there was no significant main effect of Task-Type, p>.05, but there was a main effect of
Shift, p<.01. The interaction between Task-Type and Shift was significant, p<.05, indicating a dualtask benefit for manual responses. For error rates, we compared the three Trial-types (German
single-task, DGS single-task, and German/DGS dual-task) with a Trial-Type×Shift ANOVA. There
was a significant main effect of Trial-type, p<.01, and Shift, p < .001, and the interaction between
Trial-type and Shift was also significant, p<.05, indicating that costs for a dual-task response are
lower than those for a DGS response, which are again lower than those for a German response.
References:
Emmorey, K., Borinstein, H. B., Thompson, R., & Gollan, T. H. (2008). Bimodal bilingualism.
Bilingualism: Language and Cognition, 11, 43-61.
Huestegge, L. & Koch, I. (2009). Dual-task crosstalk between saccades and manual responses.
Journal of Experimental Psychology: Human Perception and Performance, 35, 352-362.
Kiesel, A., Steinhauser, M., Wendt, M., Falkenstein, M., Jost, K., Philipp, A. M., & Koch, I. (2010).
Control and interference in task switching – A review. Psychol Bull, 136, 849-874.
Navon, D., & Miller, J. (1987). Role of outcome conflict in dual-task interference. Journal of
Experimental Psychology: Human Perception & Performance, 13, 435-448.