Object utilization and object usage: A single-case study

ABSTRACT

It has been suggested that both conceptual knowledge and the ability to infer function from structure can support object use. By contrast, we propose that object use requires solely the ability to reason about technical ends. Technical ends (e.g., cutting) are not purposes (e.g., eating), but the technical way to achieve them. This perspective suggests that there is no mutual relationship between technical ends and purposes since the same purpose (e.g., writing) can be achieved thanks to distinct technical ends (graving, tracing), and, inversely, the same technical end (e.g., tracing) can achieve different purposes (making up, writing). Thus, conceptual knowledge might determine which technical end is usually associated with a given purpose. To contribute to the discussion, we described the behaviour of a female patient with left temporal lobe lesions and bilateral frontal lobe lesions following a closed-head injury. Conceptual knowledge was impaired. She encountered difficulties in demonstrating the use of objects in isolation (e.g., using a screwdriver without the screw). The presence of a recipient (e.g., using a screwdriver with the screw) improved her performance. The performance was also normal when asked to perform unusual applications of objects to achieve a goal for which the usually applied object was not provided (e.g., screwing a screw with a knife). Consistent with the theoretical framework supported here, her performance profile suggests an intact ability to reason about technical ends (i.e., utilization), in the presence of a defective ability to determine the usual relationship between technical ends and purposes (i.e., usage).

Keywords:

• Tool use
• Apraxia
• Action
• Conceptual knowledge
• Object misuse

We are grateful to Dr Alaa Ghali for improving the English of the manuscript.

Notes

¹We follow the suggestion (Bozeat et al., 2002; Hodges et al., 2000) to use the terms ‘object’ for the implement which performs an action (e.g., a hammer) and ‘recipient’ for the recipient of the action (e.g., a nail).

²Note that items of this test refer to both small (e.g., screwdriver) and large (e.g., car) man-made objects (one item in the associative condition and five items in the categorical condition refer to large man-made objects). Some studies have reported that brain lesions can selectively impair knowledge of small or large man-made objects (Warrington & McCarthy, 1987; Warrington & Shallice, 1984). One account of these impairments is that this category specificity reflects the differential weighting of knowledge about object manipulation (Buxbaum & Saffran, 2002). However, the use of some small man-made objects does not require any ‘manipulation’ (e.g., flowerpot, mirror), while some parts of large man-made objects generally require to be ‘manipulated’ when using (e.g., car, washing machine). Note also that Buxbaum and Saffran (2002), who supported the hypothesis of differential weighting of object manipulation knowledge to account for impairments of knowledge about small or large man-made objects, assessed object manipulation knowledge in using a picture matching test in which large man-made objects were represented (e.g., washing machine, piano). Consequently, given that the theoretical dissociation between small/large or between manipulable/non-manipulable objects remains unclear, we considered the Functional Picture Matching Test for assessing general knowledge about man-made object functions, without taking into consideration the real size of objects.

³The group of controls matched with MJC performed the Usual Use of Objects Test with only one of their hands. Given that we did not have data from controls completing the test with one hand and then the other, MJC was also assessed with only one hand. The right hand was chosen because of better performance in the Imitation of Meaningless Gestures Test.