Elizabeth Jiwon Im

All Publications

• Effector independence in writing. Journal of experimental psychology. Human perception and performance McCloskey, M., Jiwon Im, E., Wong, K. W., Luo, E., Upadya, N., Srijomkwan, K., Chen, C. 2025; 51 (5): 643-663

  Abstract

  This study concerns motor representations acquired in learning to write. Most theorists assume that at the highest levels of the motor programming hierarchy, learned motor programs for writing characters (e.g., "A") are effector-independent, specifying the order and trajectories of writing strokes in a form not tied to specific effectors (e.g., right hand). On this view, once a high-level motor program has been learned with one effector, that same program will be used for writing with other effectors. However, in experiments conducted during 2018-2024, we found a clear qualitative difference between dominant and nondominant hands for participants writing in uppercase print: the direction of horizontal writing strokes (rightward or leftward) varied systematically with the hand used for writing. We interpret this phenomenon as evidence against the standard effector independence hypothesis and offer two alternatives. The first proposes that even the highest level motor programs are effector-specific. The second assumes that high-level motor programs learned with one effector can drive writing with other effectors, yet may be nonoptimal for a novel effector, in which case a new motor program may be generated. Both hypotheses imply a dual-route conception in which a high-level motor program may be activated either by retrieving a previously learned program from memory, or by generating a new program on the fly. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

  View details for DOI 10.1037/xhp0001308

  View details for PubMedID 40126582

• Early Neural Development of Social Interaction Perception: Evidence from Voxel-Wise Encoding in Young Children and Adults JOURNAL OF NEUROSCIENCE Im, E., Shirahatti, A., Isik, L. 2025; 45 (1)

  Abstract

  From a young age, children have advanced social perceptual and reasoning abilities. However, the neural development of these abilities is still poorly understood. To address this gap, we used fMRI data collected while 122 3-12-year-old children (64 females) and 33 adults (20 females) watched an engaging and socially rich movie to investigate how the cortical basis of social processing changes throughout development. We labeled the movie with visual and social features, including motion energy, presence of a face and a social interaction, theory of mind (ToM) events, valence, and arousal. Using a voxel-wise encoding model trained on these features, we found that models based on visual (motion energy) and social (faces, social interaction, ToM, valence, and arousal) features can both predict brain activity in children as young as 3 years old across the cortex, with particularly high predictivity in motion-selective middle temporal region and the superior temporal sulcus (STS). Furthermore, models based on individual social features showed that while there may be some development throughout childhood, social interaction information in the STS is present in children as young as 3 years old and appears adult-like by age 7. The current study, for the first time, links neural activity in children to predefined social features in a narrative movie and suggests social interaction perception is supported by early developing neural responses in the STS.

  View details for DOI 10.1523/JNEUROSCI.2284-23.2024

  View details for Web of Science ID 001403299800002

  View details for PubMedID 39467639

  View details for PubMedCentralID PMC11694395