How does cognitive load affect social interactions? Dataset and Analysis

Project abstract:

Many situations involve processing social and non-social information simultaneously. However, is not known how performance is affected in such situations. Here, we examined how our ability to process social information is affected by the need to keep track of non-social information. Participants were instructed to carry out two tasks within each trial. The social task involved referential communication – requiring participants to use social cues to guide their decisions. At the same time, cognitive load was manipulated by requiring participants to remember non-social information in the form of either one or three two-digit numbers visually presented before each social task stimulus. Results indicate that the cognitive demands of simultaneously processing social and non-social information impair social information processing. Specifically, keeping in mind three numbers slowed participants' ability to use another person's perspective to guide decisions. These results suggest that social information processing requires domain-general resources that are depleted under cognitive load.

Data:

These files include our dataset, as well as the scripts used to analyze the data and create graphs of the results. You will need to download R (http://www.r-project.org/) to use these files. Data are from 29 adult participants. Participants completed an adapted version of the “Director Task” (Dumontheil, Hillebrandt, Apperly, & Blakemore, 2012) with an embedded working memory (WM) Task component. Afterwards, participants completed a verbal reverse digit-span task as a measure of WM capacity and the Interpersonal Reactivity Index questionnaire to assess individual differences in trait perspective taking (Davis, 1980).

Data Analysis:

We used the lme4 package in R (Bates, Maechler, & Bolker, 2013) to perform a linear mixed effects analysis on the relationship between our factors of interest and accuracy and RT for both tasks. RT data from correct trials only were analyzed. To create approximately normally distributed residuals, we used a log or reciprocal function to transform RT data. We performed a two-step procedure: first, we created a global model including main and interactive effects of cognitive load (low vs. high), condition (Director Present vs. Director Absent), trial type (1-object vs. 3-object), and perspective (same vs. different) as fixed effects, and each model included a random intercept for each participant. We then compared all possible combinations[1] of the variables within our global model using an automated model selection procedure (MuMIn1.9.0; Barton, 2013). Models were ranked using Second-order Akaike Information Criterion (AICc; Burnham & Anderson, 2002). Second, after determining the best fitting model for each outcome of interest, we tested whether WM capacity or trait perspective taking explained any additional variance through likelihood ratio tests. All p-values were obtained by likelihood ratio tests comparing the best fitting model against a baseline model.
[1] Interactions were always accompanied by their respective main effects and all lower order terms

 

Update (August 8, 2013): There was a minor error in the original SocialDualTaskData.R file, which has now been corrected.