Action Possibility Judgments of People with Varying Motor Abilities Due to Spinal Cord Injury

Abstract

Predictions about one's own action capabilities as well as the action capabilities of others are thought to be based on a simulation process involving linked perceptual and motor networks. Given the central role of motor experience in the formation of these networks, one's present motor capabilities are thought to be the basis of their perceptual judgments about actions. However, it remains unknown whether the ability to form these action possibility judgments is affected by performance related changes in the motor system. To determine if judgments of action capabilities are affected by long-term changes in one's own motor capabilities, participants with different degrees of upper-limb function due to their level (cervical vs. below cervical) of spinal cord injury (SCI) were tested on a perceptual-motor judgment task. Participants observed apparent motion videos of reciprocal aiming movements with varying levels of difficulty. For each movement, participants determined the shortest movement time (MT) at which they themselves and a young adult could perform the task while maintaining accuracy. Participants also performed the task. Analyses of MTs revealed that perceptual judgments for participant's own movement capabilities were consistent with their actual performance- people with cervical SCI had longer judged and actual MTs than people with below cervical SCI. However, there were no between-group differences in judged MTs for the young adult. Although it is unclear how the judgments were adjusted (altered simulation vs. threshold modification), the data reveal that people with different motor capabilities due to SCI are not completely biased by their present capabilities and can effectively adjust their judgments to estimate the actions of others.

Motor imagery in spinal cord injured people is modulated by somatotopic coding, perspective taking, and post‐lesional chronic pain

“…After the vision, participants had to report via keyboard the shortest time in which they and a young adult could accurately perform these movements. The SCI responses were consistent with their actual performance, with worse judgments in participants with cervical lesions as compared to those with below cervical SCI (Manson et al ., ).…”

What the study of spinal cord injured patients can tell us about the significance of the body in cognition

“…Studies on SCI support this notion. Although these patients often report that they walk in their dreams (Saurat et al, 2011 ), there is evidence indicating that paraplegic patients may suffer from a dramatic reduction in their motor imagery capacities (Alkadhi et al, 2005 ; Chen et al, 2016 ; Di Rienzo, Collet, et al, 2014a ; Di Rienzo, Guillot, et al, 2014b ; Hotz-Boendermaker et al, 2008 ; Scandola, Aglioti, Pozeg, et al, 2017b ) and in the discrimination of biological motion (e.g., the direction of ambulation of a point-light walker; Arrighi et al, 2011 ), even if they are aware of their motor deficits (Manson et al, 2014 ). Again, these disorders in action representation may be topographically specific, involving actions that would be executed by the paralysed below-lesion body parts but not those performed by the above-lesion body parts (Pernigo et al, 2012 ; Scandola, Aglioti, et al, 2019a ).…”

The Impact of Limited Previous Motor Experience on Action Possibility Judgments in People with Spinal Muscle Atrophy

“…For example, prior to passing an object to a small child, we need to judge if the child can safely hold and maneuver the object. Previous studies have suggested that such action possibility judgments rely on a simulation process that utilizes linked action and perception networks [ 1 , 2 , 3 , 4 ]. Specifically, when asked to make a judgment about another person’s action, the actor first stimulates the action and forms a prediction about their own performance.…”

“…Evidence for the use of simulations in action possibility judgments has emerged from studies examining the ability to predict MT based on movement difficulty [ 2 , 3 , 5 ]. Specifically, these studies used a Fitts’s Law paradigm that characterizes the relationship between MT and movement difficulty for reciprocal upper-limb reaching movements [ 2 , 3 , 5 , 6 ].…”

“…Evidence for the use of simulations in action possibility judgments has emerged from studies examining the ability to predict MT based on movement difficulty [ 2 , 3 , 5 ]. Specifically, these studies used a Fitts’s Law paradigm that characterizes the relationship between MT and movement difficulty for reciprocal upper-limb reaching movements [ 2 , 3 , 5 , 6 ]. The Fitts’s Law equation which captures the relationship between MT and movement difficulty is: MT = a + b (log2[2A/W]), where “a” and “b” are constants that relate one’s baseline MT (y-intercept) and the change in MT for a given change in movement difficulty (slope of the regression line), respectively.…”