Stroke Structured Abstract - S #9
When stroke clients are reaching to accomplish a functional goal with a real object, they may show better organization of reaching movement than when they are simply reaching to perform the motion
CITATION: Wu, C-Y., Trombly, C. A., Lin, K-C., & Tickle-Degnen, L. (1998). Effects of object affordances on reaching performance in persons with and without cerebral vascular accident (CVA). American Journal of Occupational Therapy, 52, 447-456.
LEVEL OF EVIDENCE: IC1c
How do object affordances affect reaching performance in stroke and healthy subjects?
Counterbalanced repeated-measure design (RCT)
Subjects were randomly assigned to sequence of conditions.
SAMPLING PROCEDURE/INCLUSION CRITERIA
Post-CVA subjects were recruited from stroke clubs in the greater Boston area. Healthy subjects were recruited from an elderly housing unit and a college program for elders. All subjects were right-handed, were able to understand and respond to instruction given by the experimenter, and had movement in the proximal part of the impaired arm.
Stroke = 14
Control = 24
Stroke = 9
Control = 7
Stroke = 5
Control = 7
Stroke = 61.8
Control = 63.2
LCVA = 8
RCVA = 5
Other = 1
Attrition = 0
One subject was not recorded as LCVA or RCVA.
Reaching kinematics calculated from data collected by OPTOTRAK/3020, three-dimensional infrared motion analysis system. Intraclass correlation (ICC) > .99
Total movement time (MT) [speed]
Total displacement (TD) [amount of reach]
Percentage of reach where peak velocity occurs (PPV) [strategy]
Number of movement units (MU) [smoothness]
Amplitude of peak velocity (PV) [force]
Condition 1: Enriched Affordance Condition - The subjects reached forward to a food chopper and pushed down on the handle to chop a fresh mushroom.
Condition 2: Impoverished Affordance Condition - the subjects reached forward to the chopper without anything in it and pushed down on the handle. The chopper was covered with blue cardoard so that its shape and contents were not fully conveyed to the subject.
WHO DELIVERED INTERVENTION
FREQUENCY & DURATION
Each condition was repeated 10 times, with rest between conditions, all within 1 day.
Significant effects for:
Movement time (F [1,12] = 4.86, p = .0239, r =.54)
Total displacement (F [1,12 = 3.48, p = .0433, r = .47)
Movement units (F [1,12] = 6.24, p = .0140, r =.58)
Marginally significant effects for:
Variable of percentage of reach where peak velocity occurs (F [1,12] = 2.10, p = .0864, r = .39)
Non-significant effect for:
Peak velocity (F [1,12] = .37, p = .2784, r = .17).
Overall effect of enriched affordance: r = .44.
- Neurologically intact group
Significant and moderate effects to large enriched effects for:
Movement time (F [1,22] = 10.57, p = .0019, r = .57)
Percentage of reach where peak velocity occurs (F[1,22] = 5.96, p = .0116, r = .46).
Marginally significant and moderate effect was found for:
Total displacement (F [1,22] = 2.57, p = .0617, r = .32)
Nonsignificant and modest effect for:
Peak velocity (F [1,22] = .13, p = .3614, r = .08).
No effect for:
Movement units (F [1,22] ~ 0, p = .4749, r ~ 0).
Within Groups/Conditions/Times: Not tested
THREATS TO VALIDITY
The finding that enriched affordances had a positive effect on movement kinematics in both CVA and neurologically intact groups suggests that providing natural objects for completing a task and providing functional information on the objects may enhance the functional performance of persons who have had a stroke.
The findings showed that the enriched condition of reaching to chop the mushroom resulted in more time efficient, more direct, and smoother movement than the impoverished condition of pushing on the chopper handle. This study suggests that to enhance stroke patients' movement quality, and possibly functional performance, occupational therapists could provide natural objects for completing tasks.
Terminology used in this document is based on two systems of classification current at the time the evidence-based literature reviews were completed: Uniform Terminology for Occupational Therapy Practice-Third Edition (AOTA, 1994) and International Classification of Functioning, Disability and Health (ICIDH-2) (World Health Organization [WHO], 1999). More recently, the Uniform Terminology document was replaced by Occupational Therapy Practice Framework: Domain and Process (AOTA, 2002), and modifications to ICIDH-2 were finalized in the International Classification of Functioning, Disability and Health (WHO, 2001).
This work is based on the evidence-based literature review completed by Hui-ing Ma, ScD, OTR, and Catherine A. Trombly, ScD, OTR/L, FAOTA.
For more information about the Evidence-Based Literature Review Project, contact the Practice Department at the American Occupational Therapy Association, 301-652-6611, x 2040.
Copyright 2003 American Occupational Therapy Association, Inc. All rights reserved. This material may be reproduced and distributed without prior written consent.