Value and spatial preferences guide habitual reaching and manual object selection in primates

Habits are automatic actions shaped by prior experience, enabling efficient and fast responses in stable environments. While habitual gaze rapidly directs the eyes toward valuable objects, the mechanisms underlying habitual manual choice for reaching and grasping remain unclear. Here we show that macaque monkeys develop habitual manual choices toward previously rewarded objects through multi-day object–value learning, driven by learned value and spatial preferences.

This habitual reaching behavior persisted without object-contingent reward and showed shorter latencies than in value-deliberative tasks, consistent with automatic control. Regression analyses further revealed that manual choice was guided by learned object values, whereas visual salience had no effect, unlike gaze habits. Instead, intrinsic spatial preferences continued to bias reaching behavior even after long-term value learning.

These findings demonstrate that habitual manual choice is influenced by both long-term value memory and innate spatial preference, suggesting that the behavioral expression of habitual choice differs between manual selection and habitual gaze. This work was supported by the Basic Science Research Program (RS-2024-00339355), ASTRA Program (RS-2024-00436783), Bio&Medical Technology Development Program (RS-2025-02263832), Global-LAMP Program (RS-2023-00301976) through the National Research Foundation (NRF) of Korea, National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2024-00460364), and the Korea Research Institute of Bioscience and Biotechnology Research Initiative Program (KGM4562532). H.F.K., Y.H.K., and J.P. were supported by grants RS-2024-00339355, RS-2024-00436783, RS-2025-02263832, and RS-2023-00301976 from the National Research Foundation (NRF) of Korea.

Y.L. and Y.G.K. were supported by grant RS-2024-00460364 from the NRF of Korea, and grant KGM4562532 from the Korea Research Institute of Bioscience and Biotechnology (KRIBB). These authors contributed equally: Yun-Hyuk Kim, Jun Park and Yu Gyeong Kim. School of Biological Sciences, Seoul National University, 08826, Seoul, Republic of Korea National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Cheongju, Republic of Korea Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon, Republic of Korea Interdisciplinary Program in Neuroscience, Seoul National University, 08826, Seoul, Republic of Korea Institute for Data Innovation in Science, Seoul National University, 08826, Seoul, Republic of Korea Correspondence to Youngjeon Lee or Hyoung F.

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