Strong biomechanical constraints on young children's mental imagery of hands (original) (raw)

Motor processes in children's imagery: the case of mental rotation of hands

Developmental Science, 2005

In a mental rotation task, children 5 and 6 years of age and adults had to decide as quickly as possible if a photograph of a hand showed a left or a right limb. The visually presented hands were left and right hands in palm or in back view, presented in four different angles of rotation. Participants had to give their responses with their own hands either in a regular, palms-down posture or in an inverted, palms-up posture. For both children and adults, variation of the posture of their own hand had a significant effect. Reaction times were longer the more awkward it was to bring their own hand into the position shown in the stimulus photograph. These results, together with other converging evidence, strongly suggest that young children's kinetic imagery is guided by motor processes, even more so than adults'.

Developmental changes of the biomechanical effect in motor imagery

Experimental Brain Research, 2013

Motor imagery has been investigated in childhood and early adolescence, but not across adolescence stages; moreover, available evidence did not clarify whether the involvement of motor information in mental rotation of body parts becomes stronger or weaker during development. In the present study, we employed the hand laterality task to assess motor imagery in ninety-seven typically developing adolescents divided into three age groups (i.e., 11-12, 14-15, and 17-18 years); mental rotation of objects and letters were also assessed. as a specific marker of the motor involvement in mental rotation of body parts, we assessed the so-called biomechanical effect, that is, the advantage for judging hand pictures showing physically comfortable positions with respect to hand pictures showing physically impossible or awkward positions. Results demonstrated that the biomechanical effect did not significantly affect early adolescents' performance, whereas it became significant in 14-to 15-year-old participants and even more stronger in 17-to 18-year-old participants; this pattern did not depend on an increase in processing speed to mentally rotate both corporeal and non-corporeal (objects and letters) stimuli. the present findings demonstrated that: (1) motor imagery undergoes a continuous and progressive refinement throughout adolescence, and (2) full exploitation of motor information to mentally transform corporeal stimuli can be attained in late adolescence only.

Motor processes in children's mental rotation

Journal of Cognition and …, 2009

Previous studies with adult human participants revealed that motor activities can influence mental rotation of body parts and abstract shapes. In this study, we investigated the influence of a rotational hand movement on mental rotation performance from a developmental perspective. Children at the age of 5, 8, and 11 years and adults performed a mental rotation task while simultaneously rotating

Predictive models to determine imagery strategies employed by children to judge hand laterality.

A commonly used paradigm to study motor imagery is the hand laterality judgment task. The present study aimed to determine which strategies young children employ to successfully perform this task. Children of 5 to 8 years old (N = 92) judged laterality of back and palm view hand pictures in different rotation angles. Response accuracy and response duration were registered. Response durations of the trials with a correct judgment were fitted to a-priori defined predictive sinusoid models, representing different strategies to successfully perform the hand laterality judgment task. The first model predicted systematic changes in response duration as a function of rotation angle of the displayed hand. The second model predicted that response durations are affected by biomechanical constraints of hand rotation. If observed data could be best described by the first model, this would argue for a mental imagery strategy that does not involve motor processes to solve the task. The second model reflects a motor imagery strategy to solve the task. In line with previous research, we showed an age-related increase in response accuracy and decrease in response duration in children. Observed data for both back and palm view showed that motor imagery strategies were used to perform hand laterality judgments, but that not all the children use these strategies (appropriately) at all times. A direct comparison of response duration patterns across age sheds new light on age-related differences in the strategies employed to solve the task. Importantly, the employment of the motor imagery strategy for successful task performance did not change with age.

Developmental changes in the interference of motor processes with mental rotation

Proceedings of the 27th …, 2005

Preceding studies with adult human subjects revealed that motor activities can influence mental rotation of body parts (e.g., hands) and abstract shapes. In this study, we investigated the influence of a rotational hand movement on mental rotation performance from a developmental perspective. Five-, eight-, and eleven-year-olds and adults were given a mental rotation task while they simultaneously rotated their hand (guided by a handle) about the same axis. The direction of the manual rotation was either compatible or incompatible with the direction of the mental rotation. As a baseline, children and adults performed the mental rotation task without concurrent hand movement. Response times increased with increasing stimulus orientation angle, indicating that subjects of all age groups used mental rotation to perform the task. Older age groups showed shorter response times. A differential influence of the direction of manual rotation on mental rotation was found for five-yearolds and eight-year-olds, but not for eleven-year-olds and adults. These results suggest that the ability to dissociate motor from visual mental processes increases with age.

Examining developmental changes in children’s motor imagery: A longitudinal study

motor imagery, development, hand laterality judgment, children Using a longitudinal design, the present study examined developmental changes in the employment of (motor) imagery strategies on the hand laterality judgment (hlJ) task in children. All children (N = 23) participated three times, at ages of 5, 6, and 7 years. error percentages and response durations were compared to a priori defined sinusoid models, representing different strategies to judge hand laterality. response durations of correct and incorrect trials were included. observed data showed that task performance was affected by motor constraints, both in children who performed accurately at 5 years of age and in the children who did not. this is the first study to show that 5-year-olds-even when not successful at the task-employ motor imagery when engaged in this task. importantly, although the children became faster and more accurate with age, no developmental changes in the employed motor imagery strategy were observed at ages of 5, 6, and 7 years. We found that 5-year-old children are able to use a motor imagery strategy to perform the hlJ task. Although performance on this task improved with age, our analyses showed that the employed strategy to solve this task remained invariant across age.

Mental Representation of Arm Motion Dynamics in Children and Adolescents

PLoS ONE, 2013

Motor imagery, i.e., a mental state during which an individual internally represents an action without any overt motor output, is a potential tool to investigate action representation during development. Here, we took advantage of the inertial anisotropy phenomenon to investigate whether children can generate accurate motor predictions for movements with varying dynamics. Children (9 and 11 years), adolescents (14 years) and young adults (21 years) carried-out actual and mental arm movements in two different directions in the horizontal plane: rightwards (low inertia) and leftwards (high inertia). We recorded and compared actual and mental movement times. We found that actual movement times were greater for leftward than rightward arm movements in all groups. For mental movements, differences between leftward versus rightward movements were observed in the adults and adolescents, but not among the children. Furthermore, significant differences between actual and mental times were found at 9 and 11 years of age in the leftward direction. The ratio R/L (rightward direction/leftward direction), which indicates temporal differences between low inertia and high inertia movements, was inferior to 1 at all ages, except for the mental movements at 9 years of age, indicating than actual and mental movements were shorter for the rightward than leftward direction. Interestingly, while the ratio R/L of actual movements was constant across ages, it gradually decreased with age for mental movements. The ratio A/M (actual movement/mental movement), which indicates temporal differences between actual and mental movements, was near to 1 in the adults' groups, denoting accurate mental timing. In children and adolescents, an underestimation of mental movement times appeared for the leftward movements only. However, this overestimation gradually decreased with age. Our results showed a refinement in the motor imagery ability during development. Action representation reached maturation at adolescence, during which mental actions were tightly related to their actual production.

Body Context and Posture Affect Mental Imagery of Hands

PLoS ONE, 2012

Different visual stimuli have been shown to recruit different mental imagery strategies. However the role of specific visual stimuli properties related to body context and posture in mental imagery is still under debate. Aiming to dissociate the behavioural correlates of mental processing of visual stimuli characterized by different body context, in the present study we investigated whether the mental rotation of stimuli showing either hands as attached to a body (hands-on-body) or not (hands-only), would be based on different mechanisms. We further examined the effects of postural changes on the mental rotation of both stimuli. Thirty healthy volunteers verbally judged the laterality of rotated hands-only and hands-on-body stimuli presented from the dorsum-or the palm-view, while positioning their hands on their knees (front postural condition) or behind their back (back postural condition). Mental rotation of hands-only, but not of hands-on-body, was modulated by the stimulus view and orientation. Additionally, only the hands-only stimuli were mentally rotated at different speeds according to the postural conditions. This indicates that different stimulus-related mechanisms are recruited in mental rotation by changing the bodily context in which a particular body part is presented. The present data suggest that, with respect to hands-only, mental rotation of hands-on-body is less dependent on biomechanical constraints and proprioceptive input. We interpret our results as evidence for preferential processing of visual-rather than kinestheticbased mechanisms during mental transformation of hands-on-body and hands-only, respectively.

Effect of biomechanical constraints in the hand laterality judgment task: Where does it come from?

2012

Several studies have reported that, when subjects have to judge the laterality of rotated hand drawings, their judgment is automatically influenced by the biomechanical constraints of the upper limbs. The prominent account for this effect is that, in order to perform the task, subjects mentally rotate their upper limbs toward the position of the displayed stimulus in a way that is consistent with the biomechanical constraints underlying the actual movement. However, the effect of such biomechanical constraints was also found in the responses of motor-impaired individuals performing the hand laterality judgment task, which seems at odds with the “motor imagery” account for this effect. In this study, we further explored the source of the biomechanical constraint effect by assessing the ability of an individual (DC) with a congenital absence of upper limbs to judge the laterality of rotated hand or foot drawings. We found that DC was as accurate and fast as control participants in judging the laterality of both hand and foot drawings, without any disadvantage for hands when compared to feet. Furthermore, DC’s response latencies for hand drawings were influenced by the biomechanical constraints of hand movements in the same way as control participants’ response latencies. These results suggest that the effect of biomechanical constraints in the hand laterality judgment task is not strictly dependent on “motor imagery” and can arise from the visual processing of body parts being sensitive to such constraints.

The influence of hands posture on mental rotation of hands and feet

Experimental Brain Research, 2007

Behavioural and functional neuroanatomy studies demonstrate that mental rotation of body parts is carried out through a sort of inner motor simulation. Here we examined whether changes of hands posture influence the mental rotation of hands and feet. Twenty healthy subjects were asked to verbally judge the laterality of hands and feet pictures in two different postural conditions. In one condition, subjects kept hands on their knees in anatomical position; in the other, their hands were kept in an unusual posture with intertwined fingers, behind the back. Results show that mental rotation of hands but not of feet was influenced by changes in hands posture. Indeed, while mental rotation of hands was faster in the front than in the back hands position, no similar effect was found when mentally rotating feet. Thus, sensory-motor and postural information coming from the body may influence mental rotation of body parts according to specific, somatotopic rules.