Affordances after spinal cord injury

Spinal cord injury can cause cognitive impairments even when no cerebral lesion is appreciable. As patients are forced to explore the environment in a non-canonical position (i.e., seated on a wheelchair), a modified relation with space can explain motor-related cognitive differences compared to non-injured individuals. Peripersonal space is encoded in motor terms, that is, in relation to the representation of action abilities and is strictly related to the affordance of reachability. In turn, affordances, the action possibilities suggested by relevant properties of the environment, are related to the perceiver's peripersonal space and motor abilities. One might suppose that these motor-related cognitive abilities are compromised when an individual loses the ability to move. We shed light on this issue in 10 patients with paraplegia and 20 matched controls. All have been administered an affordances-related reachability judgement task adapted from Costantini, Ambrosini, Tieri, Sinigaglia, and Committeri (2010, Experimental Brain Research, 207, 95) and neuropsychological tests. Our findings demonstrate that patients and controls show the same level of accuracy in estimating the location of their peripersonal space boundaries, but only controls show the typical overestimation of reaching range. Secondly, patients show a higher variability in their judgements than controls. Importantly, this finding is related to the patients’ ability to perform everyday tasks. Finally, patients are not faster in making their judgements on reachability in peripersonal space, while controls are. Our results suggest that not moving freely or as usual in the environment impact decoding of action-related properties even when the upper limbs are not compromised.     

The Affective Significance of Skin Conductance Activity During a Difficult Problem-solving Task

The meaning of spontaneous skin conductance activity, and its relevance to appraisal theory, are examined. Spontaneous skin conductance activity is hypothesised to reflect task engagement, and thus to be correlated with appraisals of problem-focused coping potential. In a within-subjects design, subjects solved anagrams in which task difficulty was manipulated by varying both the difficulty of the anagrams and the amount of time available to solve them. In the most difficult condition, appraisals of coping potential were expected, and observed, to be especially low, and these appraisals were predicted to produce selective disengagement from the task, yielding reduced skin conductance activity. Within trials, skin conductance activity increased at the start of the trials in all conditions, but decreased by the end of the trials in the most difficult condition only. At the end of the trials, both spontaneous response rate and maximum response amplitude were positively correlated, within-subjects, with appraisals of coping potential, and, even after controlling for task difficulty, with solving the anagram. These findings support the hypothesised relation between appraised coping potential and spontaneous skin conductance activity, and the interpretation of this activity as reflecting task engagement.