Christophe Jarry

Grasping the Affordances, Understanding the Reasoning: Toward a Dialectical Theory of Human Tool Use.

One of the most exciting issues in psychology is, What are the psychological mechanisms underlying human tool use? The computational approach assumes that the use of a tool (e.g., a hammer) requires the extraction of sensory information about object properties (heavy, rigid), which can then be translated into appropriate motor outputs (grasping, hammering). The ecological approach suggests that humans perceive not the properties of tools per se but what they afford (a heavy, rigid object affords pounding). This is the theory of affordances. In this article, we examine the potential of the computational view and the ecological view to account for human tool use. To anticipate our conclusions, neither of these approaches is likely to be satisfactory, notably because of their incapacity to resolve the issue of why humans spontaneously use tools. In response, we offer an original theoretical framework based on the idea that affordance perception and technical reasoning work together in a dialectical way. The thesis we defend here is that humans have the ability to view body action as a problem to be solved. It is precisely at this point that technical reasoning occurs. However, even if the ability to do technical reasoning gives humans the illusion of constantly doing less (e.g., TV remote control), they are still forced to use body action-and to perceive affordances-to operate the product of the reasoning (pushing buttons with the fingers). This is the principle of dialectic.

Unusual use of objects after unilateral brain damage. The technical reasoning model

It has been suggested that gesture engrams, conceptual knowledge and/or the ability to infer function from structure can support object use. The present paper proposes an alternative view which is based upon the idea that object use requires solely the ability to reason about technical means provided by objects. Technical means are abstract principles which are not linked with any object representation (e.g., cutting involves the opposition between dense and permeable material). The technical reasoning model predicts that the inability to perform technical reasoning should impair performance in any situation requiring the use of objects (in a conventional way or not). Twenty left brain-damaged (LBD) patients, 11 right brain-damaged (RBD) patients and 41 healthy controls were examined on experimental tests assessing the conventional use of objects (e.g., screwing a screw with a screwdriver), conceptual knowledge about object function, pantomime of object use and recognition of object utilization gestures. We also designed the Unusual Use of Objects Test, which demands unusual applications of objects to achieve a purpose for which the usually applied object is not provided (e.g., screwing a screw with a knife). The key findings are that only LBD patients have more difficulties on the Unusual Use of Objects Test than controls or RBD patients, and that the severity of their impairment is correlated with that on conventional use of objects. Correlations with tests assessing conceptual knowledge as well as with tests of pantomime of object use and recognition of object utilization gestures were weaker. These results support the technical reasoning model and question the role of conceptual knowledge and gesture engrams in object use. Since the technical reasoning model also predicts two distinct technical disorders, the discussion focuses on the existence of these disorders in regard to individual performance profiles obtained in the Unusual Use of Objects Test.

Re-examining the gesture engram hypothesis. New perspectives on apraxia of tool use.

In everyday life, we are led to reuse the same tools (e.g., fork, hammer, coffee-maker), raising the question as to whether we have to systematically recreate the idea of the manipulation which is associated with these tools. The gesture engram hypothesis offers a straightforward answer to this issue, by suggesting that activation of gesture engrams provides a processing advantage, avoiding portions of the process from being reconstructed de novo with each experience. At first glance, the gesture engram hypothesis appears very plausible. But, behind this beguiling simplicity lies a set of unresolved difficulties: (1) What is the evidence in favour of the idea that the mere observation of a tool is sufficient to activate the corresponding gesture engram? (2) If tool use can be supported by a direct route between a structural description system and gesture engrams, what is the role of knowledge about tool function? (3) And, more importantly, what does it mean to store knowledge about how to manipulate tools? We begin by outlining some of the main formulations of the gesture engram hypothesis. Then, we address each of these issues in more detail. To anticipate our discussion, the gesture engram hypothesis appears to be clearly unsatisfactory, notably because of its incapacity to offer convincing answers to these different issues. We conclude by arguing that neuropsychology may greatly benefit from adopting the hypothesis that the idea of how to manipulate a tool is recreated de novo with each experience, thus opening interesting perspectives for future research on apraxia.

Apraxia of tool use: More evidence for the technical reasoning hypothesis

Various distinct cognitive processes such as semantic memory, executive planning or technical reasoning have been shown to support tool use. The aim of this study is to investigate the relationship between these processes. To do so, a large apraxia battery was submitted to 16 patients with left brain-damage (LBD) and aphasia and 19 healthy controls. The battery included: classical apraxia tests (Pantomime of Tool Use and Single Tool Use), familiar and novel tool use tests (Tool-Object Pairs and Sequential Mechanical Problem-Solving), semantic memory tests (Recognition of tool utilization gestures and Functional and Categorical Associations) as well as the Tower Of London. The Sequential Mechanical Problem-Solving task is a new task which permits the evaluation of pre-planning in unusual tool use situations. In this task as well as in the Tool-Object Pairs task, participants solved a tool use problem in a Choice and a No-Choice condition to examine the effect of tool selection. Globally, left brain damaged patients were impaired as compared to controls. We found high correlations in left brain damaged patients between performances on classical apraxia tests, familiar and novel tool use tests and Functional and Categorical Associations but no significant association between these performances and Tower Of London or Recognition of tool utilization gestures. Furthermore, the two conditions (Choice and No-Choice) of Tool-Object Pairs and Sequential Mechanical Problem-Solving were associated. In sum, all tasks involving tool use are strongly associated in LBD patients. Moreover, the ability to solve sequential mechanical problems does not depend on executive planning. Also, tool use appears to be associated with knowledge about object function but not with knowledge about tool manipulation. Taken together, these findings indicate that technical reasoning and, to a lesser extent, semantic memory may both play an important role in tool use.

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).

Apraxia and Alzheimer’s Disease: Review and Perspectives

Apraxia is one of the cognitive deficits that characterizes Alzheimer’s disease. Despite its prevalence and relevance to diagnosing Alzheimer’s disease, this topic has received little attention and is without comprehensive review. The review herein is aimed to fill this gap by first presenting an overview of the impairment caused in different clinical situations: pantomime of tool use, single tool use, real tool use, mechanical problem solving, function and manipulation knowledge tasks, and symbolic/meaningless gestures. On the basis of these results, we then propose alternative interpretations regarding the nature of the underlying mechanisms impaired by the disease. Also presented are principal methodological issues precluding firm conclusions from being drawn.

Different constraints on grip selection in brain-damaged patients: Object use versus object transport

The present study discusses the presence of different constraints on action selection during object use versus object transport. Sixteen left brain-damaged (LBD) patients, 10 right brain-damaged (RBD) and 35 healthy controls were examined on a grip preference test consisting of a grasping-to-transport and a grasping-to-use condition. Assessment included a general praxis testing (pantomime production, object utilization gesture recognition and object use). We also reported the case of a close-head injury patient (DR) with an atypical behavioural pattern. Our results supported the different constraint hypothesis. While several LBD and RBD patients performed inappropriate grips in the grasping-to-transport condition, only two patients (L2 and DR) used inappropriate grips in the grasping-to-use condition. No correlation was found between the two conditions of the grip preference test and measures of the general praxis testing. The discussion focuses on the nature of constraints on grip selection during object use and object transport.

Mechanical problem-solving strategies in Alzheimer's disease and semantic dementia.

OBJECTIVE The goal of this study was to explore whether the tool-use disorders observed in Alzheimers disease (AD) and semantic dementia (SD) are of the same nature as those observed in left brain-damaged (LBD) patients. Recent evidence indicates that LBD patients with apraxia of tool use encounter difficulties in solving mechanical problems, characterized by the absence of specific strategies. This pattern may show the presence of impaired mechanical knowledge, critical for both familiar and novel tool use. So, we explored the strategies followed by AD and SD patients in mechanical problem-solving tasks in order to determine whether mechanical knowledge is also impaired in these patients. METHOD We used a mechanical problem-solving task in both choice (i.e., several tools were proposed) and no-choice (i.e., only 1 tool was proposed) conditions. We analyzed quantitative data and strategy profiles. RESULTS AD patients but not SD patients met difficulties in solving mechanical problem-solving tasks. However, the key finding is that AD patients, despite their difficulties, showed strategy profiles that are similar to that of SD patients or controls. Moreover, AD patients exhibited a strategy profile distinct from the one previously observed in LBD patients. CONCLUSIONS Those observations lead us to consider that difficulties met by AD patients to solve mechanical problems or even to use familiar tools may not be caused by mechanical knowledge impairment per se. In broad terms, what we call apraxia of tool use in AD is certainly not the same as apraxia of tool use observed in LBD patients. (PsycINFO Database Record

Make a gesture and I will tell you what you are miming. Pantomime recognition in healthy subjects.

The present paper deals with the question of how people recognize tool-use/transitive actions performed by others. The direct-matching hypothesis assumes that transitive gestures produced by others are recognized by directly activating the same gesture engrams used for making the gesture oneself. By contrast, the context hypothesis posits that the observation of the gesture alone is not sufficient, and that additional contextual information is necessary for recognizing the action. The aim of the present paper is to decide between these two hypotheses. To achieve this purpose, we asked healthy older adults (performers) to mime the use of tools (Experiment 1a). Performance was videotaped and presented to healthy younger adults (observers) in two conditions: (1) Naming the tool associated with the gesture made by the performer (naming condition); (2) Choosing the correct name from 10 alternatives (choice condition). Our results indicated that the performance in the naming condition was relatively poor, emphasizing that people are far from perfect at recognizing pantomimes without contextual information. We also found a great variability among observers, suggesting that the same gesture could evoke different tool-use actions. The performance was better in the choice condition. So, observers benefited from the introduction of tool names. This pattern of results could also be explained by a sequence effect, a lexical-decision effect or an item-selection effect. Experiments 1b and 2 ruled out these possibilities. In short, these points make it difficult to believe that people recognize the actions performed by others by directly activating gesture engrams. Our findings are more consistent with the context hypothesis.

A cognitive-based model of tool use in normal aging

ABSTRACT While several cognitive domains have been widely investigated in the field of aging, the age-related effects on tool use are still an open issue and hardly any studies on tool use and aging is available. A significant body of literature has indicated that tool use skills might be supported by at least two different types of knowledge, namely, mechanical knowledge and semantic knowledge. However, neither the contribution of these kinds of knowledge to familiar tool use, nor the effects of aging on mechanical and semantic knowledge have been explored in normal aging. The aim of the present study was to fill this gap. To do so, 98 healthy elderly adults were presented with three tasks: a classical, familiar tool use task, a novel tool use task assessing mechanical knowledge, and a picture matching task assessing semantic knowledge. The results showed that aging has a negative impact on tool use tasks and on knowledge supporting tool use skills. We also found that aging did not impact mechanical and semantic knowledge in the same way, confirming the distinct nature of those forms of knowledge. Finally, our results stressed that mechanical and semantic knowledge are both involved in the ability to use familiar tools.