The control of routine action is a complex process subject both to minor lapses in normals and to more severe breakdown followingcertain forms of neurological damage. A number of recent empirical studies (e.g. Humphreys & Ford, 1998; Schwartz et al., 1991, 1995, 1998) have examined the details of breakdown in certain classes of patient, and attempted to relate the findings to existing psychological theory. This paper complements those studies by presenting a computational model of the selection of routine actions based on competitive activation within a hierarchically organised network of action schemas (cf. Norman & Shallice, 1980, 1986). Simulations are reported which demonstrate that the model is capable of organised sequential action selection in a complex naturalistic domain. It is further demonstrated that, after lesioning, the model exhibits behaviour qualitatively equivalent to that observed by Schwartz et al., in their action disorganisation syndrome patients.

■ We investigated why self-produced tactile stimulation is perceived as less intense than the same stimulus produced externally. A tactile stimulus on the palm of the right hand was either externally produced, by a robot or self-produced by the subject. In the conditions in which the tactile stimulus was self-produced, subjects moved the arm of a robot with their left hand to produce the tactile stimulus on their right hand via a second robot. Subjects were asked to rate intensity of the tactile sensation and consistently rated self-produced tactile stimuli as less tickly, intense, and pleasant than externally produced tactile stimuli. Using this robotic setup we were able to manipulate the correspondence between the action of the subjects ’ left hand and the tactile stimulus on their right hand. First, we parametrically varied the delay between the movement of the left hand and the resultant movement of the tactile stimulus on the right hand. Second, we implemented varying degrees of trajectory perturbation and varied the direction of the tactile stimulus movement as a function of the direction of left-hand movement. The tickliness rating increased signiªcantly with increasing delay and trajectory perturbation. This suggests that self-produced movements attenuate the resultant tactile sensation and that a necessary requirement of this attenuation is that the tactile stimulus and its causal motor command correspond in time and space. We propose that the extent to which self-produced tactile sensation is attenuated (i.e., its tickliness) is proportional to the error between the sensory feedback predicted by an internal forward model of the motor system and the actual sensory feedback produced by the movement. ■

This paper offers a framework for consciousness of internal reality. Recent PET experiments are reviewed, showing partial overlap of cortical activation during self-produced actions and actions observed from other people. This overlap suggests that representations for actions may be shared by several individuals, a situation which creates a potential problem for correctly attributing an action to its agent. The neural conditions for correct agency judgments are thus assigned a key role in self/other distinction and self-consciousness. A series of behavioral experiments that demonstrate, in normal subjects, the poor monitoring of action-related signals and the difficulty in recognizing self-produced actions are described. In patients presenting delusions, this difficulty dramatically increases and actions become systematically misattributed. These results point to schizophrenia and related disorders as a paradigmatic alteration of a ‘‘Who?’ ’ system for self-consciousness.

Over the last several years, researchers have begun to appreciate the ways in which questions of interest to personality and social psychologists can be addressed with neuropyschological case material (e.g., Klein & Kihlstrom, 1998; Klein, Loftus, &

Abstract: Autism provides a model for exploring the nature of self-consciousness: self-consciousness requires the ability to reflect on mental states, and autism is a disorder with a specific impairment in the neurocognitive mechanism underlying this ability. Experimental studies of normal and abnormal development suggest that the abilities to attribute mental states to self and to others are closely related. Thus inability to pass standard ‘theory of mind ’ tests, which refer to others ’ false beliefs, may imply lack of self-consciousness. Individuals who persistently fail these tests may, in the extreme, be unable to reflect on their intentions or to anticipate their own actions. In contrast, individuals with high-functioning autism or Asperger syndrome often possess a late-acquired, explicit theory of mind, which appears to be the result of effortful learning. An experimental study with three people with Asperger syndrome suggested that level of performance on standard theory of mind tasks was strongly related to the ability to engage in introspection. Qualitative differences in the introspections of high-functioning people with autism are also reflected in autobiographical accounts which may give a glimpse of what it is like to be autistic.

We used fMRI to examine neural responses when subjects experienced a tactile stimulus that was either self-produced or externally produced. The somatosensory cortex showed increased levels of activity when the stimulus was externally produced. In the cerebellum there was less activity associated with a movement that generated a tactile stimulus than with a movement that did not. This difference suggests that the cerebellum is involved in predicting the specific sensory consequences of movements and providing the signal that is used to attenuate the sensory response to self-generated stimulation. In this paper, we use regression analyses to test this hypothesis explicitly. Specifically, we predicted that activity in the cerebellum contributes to the decrease in somatosensory cortex activity during self-produced tactile stimulation. Evidence in favor of this hypothesis was obtained by demonstrating that activity in the thalamus and primary and secondary somatosensory cortices significantly regressed on activity in the cerebellum when tactile stimuli were self-produced but not when they were externally produced. This supports the proposal that the cerebellum is involved in predicting the sensory consequences of movements. In the present study, this prediction is accurate when tactile stimuli are self-produced relative to when they are externally produced, and is therefore used to attenuate the somatosensory response to the former type of tactile stimulation but not the latter.

This chapter deals with the cognitive underpinnings of voluntary action, here defined as goal-directed behaviour. It is delineates how voluntary action emerges through the automatic acquisition of bilateral associations between cognitive codes of movement patterns and sensory movement effects. Once acquired, these associations can be used in the backward direction to choose movement patterns by activating codes of intended outcomes (the LotzeHarle principle). Actions are planned by specifying the features of intended outcomes, binding the activated feature codes, and integrating them with features of anticipated trigger stimuli. Integrated action plans are then carried out automatically as soon as the trigger stimulus is encountered.

Abstract: “Ought ” cannot be derived from “is, ” so why should facts about human nature be of interest to business ethicists? In this article, we discuss why the nature of human nature is relevant to anyone wishing to create a more just and humane workplace and society. We begin by presenting evolutionary psychology as a research framework, and then present three examples of research that illuminate various evolved cognitive programs. The first involves the cognitive foundations of trade, including a neurocognitive mechanism specialized for a form of moral reasoning: cheater detection. The second involves the moral sentiments triggered by participating in collective actions, which are relevant to organizational behavior. The third involves the evolved programs whereby our minds socially construct groups, and how these can be harnessed to reduce racism and foster true diversity in the workplace. In each case, we discuss how what has been learned about these evolved programs might inform the

To be published in Behavioral and Brain Sciences (in press)

Abstract. This paper presents a cognitive agent model capable of showing situations where self-generated actions are attributed to other agents, as, for example, for patients suffering from schizophrenia. The mechanism underlying the model involves inverse mirroring: mapping preparation states onto sensory representations of observed actions. It is shown how this mechanism can develop based on Hebbian learning. The model provides a basis for applications to human-like virtual agents in the context of for example, training of therapists or agent-based generation of virtual stories.