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Poster D41, Thursday, November 9, 6:15 – 7:30 pm, Harborview and Loch Raven Ballrooms

Neural measures of sensitivity to the acquisition of space-time mappings in an artificial semiotic system

Tania Delgado1, Tessa Verhoef1, Esther Walker1, Seana Coulson1;1UC San Diego

In languages across the world, a common strategy for expressing the meaning of temporal concepts is to recycle the language of space. The present study tested whether some time-space mappings are easier to learn by recording EEG as participants learned an artificial language derived from a social communication game. In this prior study, we equipped people with a novel communication device (a vertical bar with a knob on it) and asked them to use the bar to convey temporal concepts to each other, such as ‘past,’ ‘future,’ ‘today,’ and ‘tomorrow’. In the behavioral study, dyads consistently adopted a duration-mapping strategy early in the interaction, using larger portions of the bar to refer to temporal intervals that were longer. For example, ‘day’ took up half the bar, while ‘year’ took up the whole bar. Duration mappings were hypothesized to result from a cognitive bias. By contrast, an order-mapping strategy, using either the top or the bottom of the bar to refer to concepts in the future were more variable across dyads and were hypothesized to rely more on social interaction for their establishment. Here we asked whether the way signals emerge in these social communication games has implications for the difficulty that new individuals experience when they learn them. Accordingly, EEG was recorded as 16 healthy adults learned ‘words’ in a miniature artificial language derived from the output of one of our most successful dyads in the behavioral study. The mini-language included 16 discrete 1.5-second movements of a round knob along a vertical bar, each corresponding to a particular temporal concept (e.g., day, second, year). Participants viewed each 1.5-second signal followed by a potential English translation of the signal (e.g. yesterday), and then pushed a button to indicate whether or not the translation was correct. Participants’ response triggered a feedback tone that enabled learning. In one ‘round’, a participant saw each of the signals in the language, once paired with the matching translation, and once with a mismatching one. Each ‘block’ was comprised of three rounds, and each participant underwent two blocks of training. ERPs were time-locked to the onset of English translations. The mean amplitude of ERPs was measured 300-500ms post-stimulus onset to index N400, and 500-800ms post-stimulus to index P600. Analysis of duration mappings contrasted ERPs to matching versus mismatching translations recorded in the first and second blocks, respectively. Repeated measures ANOVA with factors Validity (match/mismatch), Block (first/second), and ROI (six regions of four electrodes each) revealed an interaction of Validity, Block, and ROI. Consistent with our hypothesis that participants have a cognitive bias that supports duration mappings, the duration violations elicited enhanced N400 in the first block, and an N400/P600 complex in the second block. Similar analysis of order mappings revealed no reliable ERP effects in the first block, and significantly larger amplitude N400 for order violations in the second block. Results support the hypothesis that participants in our subject pool have a cognitive bias that supports more rapid learning of duration than order mappings.

Topic Area: Meaning: Discourse and Pragmatics

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