ERP Neural Correlates of the Interpreter Advantage in Coordination (anonymized for review)
We hypothesized that there may be an interpreter advantage associated with the bottleneck switching component of the coordination skill, and intended to investigate the advantage and its ERP neural correlates. To achieve this goal, we conducted an ERP experiment with a Psychological Refractory Period dual-task, and analyzed the stimulus-locked and response-locked LRP onset latency, and also the behavioral data. If an advantage in coordination was to be found in the present study, the advantageous group of interpreting students would outperform in dual-task costs (the difference between dual-task and single-task conditions, with smaller costs suggesting better coordination), and the better performance would be restricted to Task 2 (suggesting better bottleneck switching component of coordination). Data obtained from the dual-task experiment included accuracy (ACC), response time (RT), stimulus-locked LRP onset latency, response-locked LRP onset latency for Task 1 and Task 2. The eight types of data were analyzed separately following the same procedure. Specifically, the dual-task costs were subjected to an ANOVA analysis with a between-group variable of Group (Interpreting, Control), a within-group variable of Condition (dual-task_100, dual-task_150, with 100, 150 referring to the three SOA conditions). The RT results exactly showed an interpreter advantage in coordination, especially in the bottleneck switching component. The same result was also found in stimulus-locked ERP onset latency, suggesting the advantage was probably due to efficient switching from the response selection of one task to that of the other at the bottleneck stage of dual-task processing. Smaller dual-task costs of stimulus-locked LRP onset latency thus constitute the neural correlates of the interpreter advantage in coordination.
Steps to reproduce
The experiments were conducted with E-prime 2.0, using a Psychological Refractory Period (PRP) dual-task. The dual-task consisted of an auditory task (Task 1:) requiring participants to determine the pitch of a tone (low/high: 350 Hz / 3250 Hz), and a visual task (Task 2), the size of a square (small/large). They needed to press the keys of “2”, “4”, “6”, and “8” on a keypad with left index, left middle, right middle and right index fingers respectively. The key-stimulus linkage was counterbalanced across participants. The experiment started with two single-task blocks of the auditory task (only tones were presented), and then blocks of the visual task (only squares), followed by eight dual-task blocks in which both types of stimuli were presented. In single-task blocks, each trial began with a white fixation for 500 ms. Then, a tone was presented for 50 ms, or a square was presented until a response was made or when it exceeded 1500 ms. In dual-task blocks, each trial began with a white fixation for 500 ms, followed by a tone of 50 ms, with a maximum response time of 1500 ms. Then, a square was presented after an SOA of 100 ms, 150 ms, or 450 ms (due to technical limitations, data of this condition failed to be recorded sometimes so it was not included in data analysis), until a response was made or when it exceeded 1500 ms. The inter-trial-interval was 400/500/600 ms. The experiment was conducted against a grey background. Participants needed to respond as accurately and quickly as possible, and respond to Task 1 first in dual-task blocks. In addition, some “catch” trials with only tones presented were added into the dual-task blocks, to discourage participants from performing the two tasks as a couplet after they have made decisions for both tasks). Each single-task block consisted of 80 trials, with 40 for each type of stimuli (i.e., low/high tones or small/large squares). Each of the eight dual-task blocks consisted of 70 trials, with five trials for each type of stimulus pair (low/high tone ~ small/large square) in each of the three SOA conditions, and 10 catch trials with five for each type of tone (low/high). In total, there were 80 trials for each stimulus type in each condition. As different tones/squares were associated with different hands, there were 80 trials for each hand in each condition for each task, and thus the LRP in each condition for each task was assumed to be averaged across 80 trials. In addition, there was a practice block of eight trials before the auditory single-task blocks and the visual single-task blocks respectively, and a practice block of 14 trials before the dual-task blocks. We recruited a group of graduates majoring in interpreting (the Interpreting group), and those in linguistics and literature (the Control group).