A cognitive-based model of tool use in normal aging

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.     

Relationship between object-related gestures and the fractionated object knowledge system

The praxic semantic system comprises a conceptual knowledge system, which stores functional information about objects, and an action knowledge system, which stores information about the correct manipulation of objects. Moreover, mechanical problem solving abilities permit to take advantages from objects structure to use unfamiliar tools or discover alternative ways of using familiar tools. This study aims at investigating whether conceptual knowledge, action knowledge and mechanical problem solving abilities intervene in the production of gestures with objects (i.e. pantomimes and object use) by testing a group of brain damaged patients. Results showed that the mechanical problem solving abilities are not sufficient to produce pantomimes and that only severe deficits in the praxic semantic system would affect the production of these gestures. Furthermore, a double dissociation was observed between mechanical problem solving abilities and the capacity to use multiple objects. Overall, the results indicate that the praxic semantic system can be disrupted at different levels, suggesting that the semantic system for object has to be conceived as fractionated in different entities.     

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.     

An update on the Conceptual-Production Systems model of apraxia: evidence from stroke

Limb apraxia is a neurological disorder characterized by an inability to pantomime and/or imitate gestures. It is more commonly observed after left hemisphere damage (LHD), but has also been reported after right hemisphere damage (RHD). The Conceptual-Production Systems model (Roy, 1996) suggests that three systems are involved in the control of purposeful movements: the conceptual, the production and the sensory/perceptual system. Depending on which system is damaged different patterns of apraxia are expressed. To determine the apraxia pattern, pantomime, delayed, and concurrent imitation tasks need to be administered, as well as conceptual tasks assessing one's knowledge of actions. Based on the model, eight patterns of apraxia should emerge. The purpose of this study is to determine whether these patterns are in fact observed in stroke patients and examine their frequency. If the performance of most stroke patients falls into one of the patterns, then we would have strong support for the conceptual-production model. Stroke (34 LHD and 39 RHD) patients and 27 age- and education-matched healthy controls participated in the study. Participants were assessed in four task modalities: pantomime, delayed imitation, concurrent imitation and conceptual knowledge (two tasks were used: tool naming by action and action identification). Patients were categorized as impaired on a task if they scored 2 SD below the mean performance of the controls for gesture production tasks, or below a cut-off score on the conceptual tasks. They were then classified into patterns depending on their performance on the four task modalities. Most patients (86%) fell into one of seven patterns originally predicted from the Conceptual-Production Systems model. The two most common patterns were deficits in pantomime and imitation with preserved gesture recognition and conduction apraxia (selective deficit in imitation). Four new patterns emerged, but mostly single cases of these were found. Overall, the study provides strong support for the Conceptual-Production Systems model.     

Conceptual and physical object qualities contribute differently to motor affordances

Priming studies have demonstrated that an object’s intrinsic and extrinsic qualities (size, orientation) influence subsequent motor behavior thus suggesting that these object qualities ‘afford’ actions that are congruent with the prime. We present four experiments that aim to evaluate the relative effect of conceptual and physical object qualities on action priming. In Experiment 1 equally graspable known and unknown tools are presented as primes. In Experiment 2 the primes depict high versus low graspable unfamiliar tools, and in Experiments 3 and 4 we present simple graspable shapes versus high graspable unfamiliar or familiar tools respectively. In all experiments the (unrelated) task consists of a timed motor response to the direction of a centrally placed arrow that is superimposed on the prime. Whereas tool familiarity reveals no significant difference on reaction time (Exp 1), responses to high graspable unfamiliar tools (Exp 2) and simple graspable shapes (Exps 3 and 4) are significantly faster. We conclude that motor affordances are most readily determined by object qualities that depend on the object’s physical appearance provided by visual information. Conceptual information about the stimuli, such as semantic category or stored knowledge about its function and associated movements, does not appear to produce detectable effects of action priming in this paradigm.     

Task novelty and intelligence

Psychology students were presented with a mental puzzle based on knowledge of geometry, with several versions of Wason's selection task, and with some tasks of essay writing. Test scores were obtained on a sentence completion test and a test of spatial configuration. With the different problem-solving tasks, a relationship between success and intellectual ability was observed only in cases where the data indicated that the subjects were familiar with the task in question. The results support the theory previously set forth by Raaheim; that only in situations where the degree of novelty is moderate, will the intelligent use of past experience prove beneficial to problem solving.     

The neural bases of complex tool use in humans

The behaviors involved in complex human tool use cut across boundaries traditionally drawn between social, cognitive, perceptual and motor processes. Longstanding neuropsychological evidence suggests a distinction between brain systems responsible for representing: (1) semantic knowledge about familiar tools and their uses, and (2) the acquired skills necessary for performing these actions. Contemporary findings in functional neuroimaging support and refine this distinction by revealing the distributed neural systems that support these processes and the conditions under which they interact. Together, these findings indicate that behaviors associated with complex tool use arise from functionally specialized networks involving temporal, parietal and frontal areas within the left cerebral hemisphere.     

Tool-use and the left hemisphere: What is lost in ideomotor apraxia?

Impaired tool related action in ideomotor apraxia is normally ascribed to loss of sensorimotor memories for habitual actions (engrams), but this account has not been tested against a hypothesis of a general deficit in representation of hand-object spatial relationships. Rapid reaching for familiar tools was compared with reaching for abstract objects in apraxic patients (N = 9) and in a control group with right hemisphere posterior stroke. The apraxic patients alone showed an impairment in rotating the wrist to correctly grasp an inverted tool but not when inverting the hand to avoid a barrier and grasp an abstract object, and the severity of the impairment in tool reaching correlated with pantomime of tool-use. A second experiment with two apraxic patients tested whether barrier avoidance was simply less spatially demanding than reaching for a tool. However, the patient with damage limited to the inferior parietal lobe still showed a selective problem for tools. These results demonstrate that some apraxic patients are selectively impaired in their interaction with familiar tools, and this cannot be explained by the demands of the task on postural or spatial representation. However, traditional engram theory cannot account for associated problems with imitation of novel actions nor the absence of any correlated deficit in recognition of the methods of grasp of common tools. A revised theory is presented which follows the dorsal and ventral streams model ( Milner & Goodale, 2008) and proposes preservation of motor control by the dorsal stream but impaired modulating input to it from the conceptual systems of the left temporal lobe.     

Cognitive task transformations

The difficulty facing an agent performing a familiar task is one of satisfactory performance rather than one of figuring out how the task is to be performed. In this paper I describe and exemplify a number of principal ways in which the physical form of tools and working environments can reduce the cognitive burden of performing routine tasks. Starting from the commonly held assumption that tools transform the structure of the tasks in which they figure, I explore some basic ways in which tools can reshape tasks to circumvent excessive demands on attention, working memory and motor control, and the need to perform the kinds of cognitive operations at which we lack proficiency. The principal task transformations that are identified include: removing superfluous actions; delegating problematic parts of a task to other people or artefacts; substituting less demanding parts of a task for parts that are cognitively difficult; rearranging a task to avoid conflict between actions; and increasing the tolerance of a task environment to sub-optimal task performance. For each transformation an account is given of the change to the task from the perspective of an agent and how this improves the cognitive congeniality of the task. For each transformation I also give an example drawn from the everyday experience of the reader of a particular tool that may be said to bring about or facilitate the transformation in question, and explain in what way the tool is able to achieve the transformation whilst still ensuring that task demands are met.     

Ideational action impairments in Alzheimer's disease

We report data from a group of patients with mild Alzheimer's disease on a range of tasks requiring either stored semantic knowledge about objects (e.g., naming object use) or the execution of action to objects (e.g., miming and using objects). We found that the patients were impaired at miming in response to objects, even when they could describe the object's function. On the other hand, copying gestures was not impaired relative to naming gestures, indicating that an ideomotor deficit in action execution, per se, was unlikely to explain the impairments in object use. We suggest instead that the patients had an impairment in stored motor programmes for action, over and above their deficits in semantic knowledge. Despite this, the patients were better at using than at miming to objects, consistent with the view that proprioceptive input (when using objects) can directly constrain selection of the appropriate motor programme for action.     

Getting a Grasp on Children’s Representational Capacities in Pantomime of Object Use

This study examined how 5- and 9-year-old children (N = 40) produce pantomimes of object use on verbal request. The task required participants to enact an action with an imagined object. Results showed that with age, children (a) proceeded from body part as object to imaginary object and (b) incorporated into their pantomimes more distinctive features of the object and its use. While the first result replicated previous findings with more items and a more sophisticated coding procedure, the latter result revealed new insights. Children’s selection of distinctive features in pantomime was related to their performance on a semantic odd-one-out task that requires the abstraction of specific features without situational support. The discussion focuses on the cognitive requirements of the task and the potential of pantomime being a reflection of children’s representational development. We suggest an explanation of the findings within the more general developmental model of Karmiloff-Smith.     

Pantomime recognition impairment in Alzheimer's disease

This study was designed to examine whether 10 AD patients with diffuse lesions and an early semantic deficit could comprehend the meaning of pantomimes and symbolic gestures. We especially wanted to determine the relationship between pantomime recognition and production. The tasks involved naming or showing an understanding (e.g., circumlocutions) of the pantomimes executed by the examiner and producing pantomimes to verbal command or to imitation. The results showed no significant relationship between pantomime comprehension and pantomime production. However, 60% of AD patients performed poorly compared to controls on the Gesture Recognition task. Gesture comprehension was highly correlated with a measure of global cognitive impairment (3MS). The data are consistent with the proposed separation of comprehension and action production systems in a cognitive model of praxis. Gesture comprehension may be diffusely distributed and thus preserved in the early stages of AD as in circumscribed lesions of the left parietal lobe.     

A model‐based approach to limb apraxia in Alzheimer's disease

Limb apraxia is a neurological deficit characterized by an inability to pantomime and/or imitate gestures, which can result from neurodegenerative disorders such as Alzheimer's disease (AD). The major goal of the study was to describe comprehensively the apraxia deficits observed in AD patients and to relate those deficits to general cognitive status, measures of daily activity, and other neuropsychological measures. Limb apraxia was assessed on a variety of conceptual and gesture production tasks in 30 AD patients. As a group, AD patients were impaired across gesture production tasks: of note was the greater impairment in imitation, as opposed to pantomime, which was especially pronounced when patients were imitating with a delay. Imitation performance was best predicted by measures of visuospatial processing, while imitation with delay was best predicted by measures of working memory. In addition, pantomime in response to pictures of tools was less accurate than Pantomime to Verbal Command and holding the tool during performance did not decrease the participants' impairment, while introducing a verbal cue during imitation increased the severity of deficits. Furthermore, investigation into patterns of deficits clearly demonstrated that the nature of limb apraxia deficits observed in AD can be quite heterogeneous and that dissociations between the conceptual and the production system exist. Finally, we also report on significant correlations between general cognitive status and limb apraxia.     

Relation between self‐knowledge reference and self‐monitoring of emotional state1

Abstract: We used a task facilitation paradigm to examine whether self‐knowledge reference and self‐monitoring have a functional relationship. Eighteen participants performed a series of tasks: self‐knowledge reference, evaluation, self‐monitoring, and semantic. Responses on the self‐knowledge reference task were faster when the previous task was self‐monitoring rather than semantic. However, responses on the self‐monitoring task were similar regardless of whether it was preceded by the self‐knowledge reference task or the evaluation task. Our results suggest that self‐monitoring induces self‐knowledge reference.     

Action goal selection and motor planning can be dissociated by tool use

The preparation of eye or hand movements enhances visual perception at the upcoming movement end position. The spatial location of this influence of action on perception could be determined either by goal selection or by motor planning. We employed a tool use task to dissociate these two alternatives. The instructed goal location was a visual target to which participants pointed with the tip of a triangular hand-held tool. The motor endpoint was defined by the final fingertip position necessary to bring the tool tip onto the goal. We tested perceptual performance at both locations (tool tip endpoint, motor endpoint) with a visual discrimination task. Discrimination performance was enhanced in parallel at both spatial locations, but not at nearby and intermediate locations, suggesting that both action goal selection and motor planning contribute to visual perception. In addition, our results challenge the widely held view that tools extend the body schema and suggest instead that tool use enhances perception at those precise locations which are most relevant during tool action: the body part used to manipulate the tool, and the active tool tip.     

Motor knowledge is one dimension for concept organization: Further evidence from a Chinese semantic dementia case

Neuropsychological and neuroimaging studies have indicated that motor knowledge is one potential dimension along which concepts are organized. Here we present further direct evidence for the effects of motor knowledge in accounting for categorical patterns across object domains (living vs. nonliving) and grammatical domains (nouns vs. verbs), as well as the integrity of other modality-specific knowledge (e.g., visual). We present a Chinese case, XRK, who suffered from semantic dementia with left temporal lobe atrophy. In naming and comprehension tasks, he performed better at nonliving items than at living items, and better at verbs than at nouns. Critically, multiple regression method revealed that these two categorical effects could be both accounted for by the charade rating, a continuous measurement of the significance of motor knowledge for a concept or a semantic feature. Furthermore, charade rating also predicted his performances on the generation frequency of semantic features of various modalities. These findings consolidate the significance of motor knowledge in conceptual organization and further highlights the interactions between different types of semantic knowledge.     

The interaction between surface color and color knowledge: behavioral and electrophysiological evidence

In this study, we used event-related potentials (ERPs) to evaluate the contribution of surface color and color knowledge information in object identification. We constructed two color-object verification tasks - a surface and a knowledge verification task - using high color diagnostic objects; both typical and atypical color versions of the same object were presented. Continuous electroencephalogram was recorded from 26 subjects. A cluster randomization procedure was used to explore the differences between typical and atypical color objects in each task. In the color knowledge task, we found two significant clusters that were consistent with the N350 and late positive complex (LPC) effects. Atypical color objects elicited more negative ERPs compared to typical color objects. The color effect found in the N350 time window suggests that surface color is an important cue that facilitates the selection of a stored object representation from long-term memory. Moreover, the observed LPC effect suggests that surface color activates associated semantic knowledge about the object, including color knowledge representations. We did not find any significant differences between typical and atypical color objects in the surface color verification task, which indicates that there is little contribution of color knowledge to resolve the surface color verification. Our main results suggest that surface color is an important visual cue that triggers color knowledge, thereby facilitating object identification.     

Tubes,tables and traps: great apes solve two functionally equivalent trap tasks but show no evidence of transfer across tasks

Previous studies on tool using have shown that presenting subjects with certain modifications in the experimental setup can substantially improve their performance. However, procedural modifications (e.g. trap table task) may not only remove task constraints but also simplify the problem conceptually. The goal of this study was to design a variation of the trap-table that was functionally equivalent to the trap-tube task. In this new task, the subjects had to decide where to insert the tool and in which direction the reward should be pushed. We also administered a trap-tube task that allowed animals to push or rake the reward with the tool to compare the subjects' performance on both tasks. We used a larger sample of subjects than in previous studies and from all the four species of great apes (Gorilla gorilla, Pan troglodytes, Pan paniscus, and Pongo pygmaeus). The results showed that apes performed better in the trap-platform task than in the trap-tube task. Subjects solved the tube task faster than in previous studies and they also preferred to rake in rather than to push the reward out. There was no correlation in the level of performance between both tasks, and no indication of interspecies differences. These data are consistent with the idea that apes may possess some specific causal knowledge of traps but may lack the ability to establish analogical relations between functional equivalent tasks.     

Dissociation and association of the embodied representation of tool-use verbs and hand verbs: An fMRI study

Embodied semantic theories suppose that representation of word meaning and actual sensory-motor processing are implemented in overlapping systems. According to this view, association and dissociation of different word meaning should correspond to dissociation and association of the described sensory-motor processing. Previous studies demonstrate that although tool-use actions and hand actions have overlapping neural substrates, tool-use actions show greater activations in frontal–parietal–temporal regions that are responsible for motor control and tool knowledge processing. In the present study, we examined the association and the dissociation of the semantic representation of tool-use verbs and hand action verbs. Chinese verbs describing tool-use or hand actions without tools were included, and a passive reading task was employed. All verb conditions showed common activations in areas of left middle frontal gyrus, left inferior frontal gyrus (BA 44/45) and left inferior parietal lobule relative to rest, and all conditions showed significant effects in premotor areas within the mask of hand motion effects. Contrasts between tool-use verbs and hand verbs demonstrated that tool verbs elicited stronger activity in left superior parietal lobule, left middle frontal gyrus and left posterior middle temporal gyrus. Additionally, psychophysiological interaction analyses demonstrated that tool verbs indicated greater connectivity among these regions. These results suggest that the brain regions involved in tool-use action processing also play more important roles in tool-use verb processing and that similar systems may be responsible for word meaning representation and actual sensory-motor processing.