Preprint · Jan 2026
Age-related differences in reference frames revealed through executed and imagined reaching movements
By Britt N, Lyons J, Kraeutner SN et al.
Previous studies have shown that during manual reaching tasks, participants show the largest distractor-related interference from distractors that are within their movement path (e.g., Tipper et al., 1992). This distractor related interference shows up as slowed response times, both in movement time (MT) and reaction time (RT, e.g., Bloesch et al., 2013). When a young adult performs a reach toward a target, if another object is between the hand and the target, the reaching movement would be affected more than in scenarios where the other object is positioned beyond the target. This slowing is believed to be due to individuals using a ‘hand-centred reference frame’ for reaching, with attention being focused predominantly on their hand before, and during, the action (Bloesch et al., 2013; Elliott et al., 2020; Lyons et al., 2006). This pattern of distractor effects on the duration of actions has been reliably shown in younger and older adults. However, a different pattern of results has been shown in older adults when they perform reaching movements when their hands are not close to their body (e.g., their hand starts a reaching movement at the far end of a table, Bloesch et al., 2013). One hypothesis for this lack of hand-centred effects is that older adults show a shift over time to prioritize their body, instead of their hands, due to decline in sensory abilities. With older age, we shift our attention more proximally, than distally, so we can better monitor trunk control and better control balance at the expense of fine motor dexterity which may have been more highly prioritized when younger. This model is known as the distal-to-proximal model for sensory aging (Kuehn et al., 2018). Unfortunately, this pattern of behaviour can be problematic as older adults may then be prone to knocking over objects when they appear within their reach or miss dangerous objects that would cause injury to their hands and other limbs. This research regarding different frames of reference for elderly versus young adults has not been replicated, and outstanding questions remain regarding the mechanisms that underlie this behavioural difference across age groups. We therefore plan to investigate these differences in reference frame behaviour across ages, as well as introduce a novel manipulation where participants only imagine moving. Because it is still possible to measure imagined movement times during imagery, yet no actual movement takes place, such a condition will help to test whether older adults prioritize attention toward their action-specific effector (their hand) during manual actions when any motor-related decline for action is removed from the task. Therefore, in the current study, we test how individuals perform reaching movements in the presence of distractors, when they have to physically execute a reaching movement with their hand compared to when they have to simply imagine acting. The first half of the experiment will involve manual reaching movements (i.e., using your hand, reach toward targets and ignore any distractors) on a digitized visual environment. In this first part of the experiment, we hope to replicate previous patterns of data with respect to differences in the action-centred representation for reaching movements. Younger adults should reveal a hand-centred reference frame, while older adults are expected to reveal a body-centred reference frame. These differences will manifest under conditions when the hand is not close to the body, with older adults always being most affected in their response times by distractors that are closer to their body as opposed to closer to their hand. For the second half of the experiment, participants will perform motor imagery (i.e., imagine seeing and feeling their hand reach toward the targets, without actually moving). If older adults show a difference in reference frame, by removing the need to move (via imagery), the imagined reference frame for older adults is still expected to show patterns congruent with a hand-centred reference frame—more similar to the patterns of data shown by younger adults. Overall, this research can highlight how the planning and online control of movement (i.e., RT and MT respectively) are differentially impacted by age and potential changes in reference-frames thought to occur with aging. By comparing across actual and imagined movements, we hope to answer whether for older adults, movement execution suppresses internal models for ‘hand-centred’ movements that are otherwise evidenced in simulated (imagined) movements? This change in behaviour would suggest that movement amplifies body-centred representations in older adults and that they may default to body-centred planning for real actions but still possess intact hand-centred internal models that emerge when execution constraints are removed. References: Bloesch, E. K., Davoli, C. C., & Abrams, R. A. (2013). Age-Related Changes in Attentional Reference Frames for Peripersonal Space. Psychological Science, 24(4), 557–561. https://doi.org/10.1177/0956797612457385 Elliott, D., Lyons, J., Hayes, S. J., Burkitt, J. J., Hansen, S., Grierson, L. E. M., Foster, N. C., Roberts, J. W., & Bennett, S. J. (2020). The multiple process model of goal-directed aiming/reaching: Insights on limb control from various special populations. Experimental Brain Research, 238(12), 2685–2699. https://doi.org/10.1007/s00221-020-05952-2 Kuehn, E., Perez-Lopez, M. B., Diersch, N., Döhler, J., Wolbers, T., & Riemer, M. (2018). Embodiment in the aging mind. Neuroscience & Biobehavioral Reviews, 86, 207–225. https://doi.org/10.1016/j.neubiorev.2017.11.016 Lyons, J., Hansen, S., Hurding, S., & Elliott, D. (2006). Optimizing rapid aiming behaviour: Movement kinematics depend on the cost of corrective modifications. Experimental Brain Research, 174(1), 95–100. https://doi.org/10.1007/s00221-006-0426-6 Tipper, S. P., Lortie, C., & Baylis, G. C. (1992). Selective reaching: Evidence for action-centered attention. Journal of Experimental Psychology: Human Perception and Performance, 18(4), 891–905. https://doi.org/10.1037/0096-1523.18.4.891