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Manipulability in Disguise: Uncovering Behavioral and Neural Differences in Processing Words Representing Small and Big Objects
Poster C69 in Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 4
Ruifeng Yu1, Hongli Liu1, Feng Gu1; 1Sichuan University
Size is a fundamental visual-spatial characteristic of the physical world. Previous studies have shown distinctive neural responses along the ventral temporal cortex when processing pictures representing small and big objects, suggesting that object size was a key dimension that organized concrete concepts. However, it remains unclear whether this size-based categorization is limited to perceptual information or extends to symbolic input, such as words. Furthermore, some behavioral studies have indicated that words denoting big objects (big words) were recognized faster than those denoting small objects (small words), but this effect remains controversial and might be task-dependent. Therefore, the present study investigates both the behavioral and neural differences in processing small and big words, and whether these differences are task-dependent. In the behavioral study, two experiments were conducted. Experiment 1 sought to replicate the effect that big words were recognized faster, using the same lexical decision task (LDT) as the original study but with a larger sample size of 60 participants. Experiment 2 used a semantic decision task (SDT) in which another sixty participants were asked to judge whether the presented word was a concrete word. The real words in Experiment 1 and concrete words in Experiment 2 were the same 40 small and 40 big words that were matched in other variables. In the EEG study, two groups of twenty-six participants separately performed the same LDT (Experiment 3) and SDT (Experiment 4), and all participants rated the object size and five size-related properties denoted by the words after the experiments. Behavioral results revealed a significant processing advantage for big words in the LDT, evidenced by shorter reaction times and lower error rates. However, this advantage was not observed in the SDT. The multivariate pattern and time generalization analyses of EEG data showed distinguishable and stable neural patterns for processing small and big words between 190 ms and 250 ms in both tasks. Additionally, in the SDT, these neural patterns persisted from 390 ms to 520 ms, reflecting a reactivation of earlier neural representations. Further analysis using multiple RSA regression explored what object properties (size and five size-related properties) could explain the representational geometry of the neural responses, which revealed that manipulability, rather than size, was the primary factor explaining the neural responses, with the significant time windows consistent with the above-chance decoding time windows in both tasks. Therefore, we suggest that manipulability is a key semantic factor underlying the neural representations of concrete concepts. In the LDT, processing small words with higher manipulability than big words may cause early simulated motor experiences, interfering with key-pressing control and leading to the observed processing advantage for big words. In the SDT, this interference effect may be counteracted by the later strong activation of the manipulability-related features of small words, which facilitates semantic decisions. These findings also highlight a flexible and two-stage processing of semantic concepts. The first stage likely involves automatic activation of language-derived representations accompanied by sensory simulations, while the second stage likely involves activation of sensory-derived representations controlled by top-down mechanisms.
Topic Areas: Meaning: Lexical Semantics,