Conditioned placebo responses

Following earlier animal research, we attempt to condition placebo effects in human subjects. Four groups of 8 voluntary subjects were told that the experimenters would test a powerful new analgesic cream over three sessions by assessing its ability to reduce experimentally induced pain. The analgesic cream was, in fact, a placebo. In the first session all subjects were tested with and without the cream to assess their placebo response. In the second session, to condition two groups (with differing stimulation levels) to experience pain relief in response to the placebo, we repeatedly paired a reduction in nocioceptive stimulation with placebo administration. (Subjects were unaware that stimulation levels were manipulated). To condition the other two groups (with different stimulation levels) to experience an exacerbation of the pain, we paired an increase in nocioceptive stimulation with placebo administration. In the third session, all subjects were again tested for placebo response. Results suggested that placebo responses are conditionable in the laboratory in both a positive and negative direction. The clinical implications of a learning theory of placebo behavior are discussed.     

Social-psychological correlates of adolescent and youthful suicide

Recently it has been suggested that social-psychological profiles of suicide attempters are useful to identify high-risk persons. There also is evidence that the complexity of interpersonal and intrapersonal factors constrict the extent to which such identification can be made. Using data from a nonprobability sample of 455 adolescent and youthful committers to test the hypothesis that attempters and committers do not differ with respect to environmental and stress-producing factors, the results reveal some differences between committers and attempters. Social-psychological characteristics of committers and factors relating to their social support systems are also discussed in the context of these differences.     

Coordination Dynamics of the Bipedal Galloping Pattern

A motion equation in relative phase was developed that incorporates the spatial-temporal pattern of the bipedal gallop along with the more commonplace patterns of the bipedal jump and walk-run. In 3 experiments, human participants (N = 6 per experiment) simulated the bipedal gait patterns through the rhythmic motions of hand-held pendulums. Predictions of the motion equation for coordination equilibria and their respective degrees of stability were confirmed. In particular, the gallop pattern was less stable than the fundamental in-phase and antiphase patterns but changed in qualitatively similar ways to those gaits as a function of limb asymmetry and movement frequency. The relation between the modeled coordination dynamics and the kinematic characteristics of real bipedal galloping is discussed     

CHOICE-MAKING TREATMENT OF YOUNG CHILDREN'S SEVERE BEHAVIOR PROBLEMS

The choice-making behavior of 5 young children with developmental disabilities who engaged in aberrant behavior was studied within a concurrent operants framework. Experimental analyses were conducted to identify reinforcers that maintained aberrant behavior, and functional communication training packages were implemented to teach the participants to gain reinforcement using mands. Next, a choice-making analysis, in which the participants chose one of two responses (either a mand or an alternative neutral response) to obtain different durations and qualities of reinforcement, was conducted. Finally, treatment packages involving choice making via manding were implemented to decrease inappropriate behavior and to increase mands. The results extended previous applications of choice making to severe behavior disorders and across behaviors maintained by positive and negative reinforcement.     

Electrode placement,EMG feedback,and relaxation for tension headaches

Fifteen tension headache subjects were allocated to one of three groups: direct EMG feedback (from a site corresponding to the source of pain), indirect EMG feedback (from a site not corresponding to the source of the pain) and relaxation instructions. There were two base-line, six treatment and one post-treatment sessions. No significant differences were found between base-line and post-treatment EMG levels, for any of the groups; however, some significant reductions in levels were obtained within sessions. EMG levels recorded during headache attacks did not differ significantly from levels recorded during base-line. Frequency and intensity of headaches were significantly reduced, particularly in the relaxation group. At follow-up this improvement was maintained for subjects with forehead pain, but differences between the groups had disappeared.     

Active regulation to be lean by rats with ventromedial hypothalamic lesions.

Adult female Long-Evans rats with direct-current electrolytic or radio-frequency thermocoagulatory lesions of the ventromedial hypothalamus (VMH) lived on pellet fragments or a powdered chow containing as much as 1.2% quinine sulfate by weight or lived in Skinner boxes with 45-mg Noyes pellets delivered contingent on fixed ratios (FR) of lever pressing up to FR 128. As had been found previously for intact rats, the body weights maintained by VMH rats were determined by the percentage of quinine sulfate in or the contingency of reinforcement of the food on which they lived. Even when the rats lived on highly adulterated or response-contingent food and were lean, they ate more of that food when the ambient temperature was reduced and less of that food during several weeks of forced feeding of eggnog by gavage. Weight maintenance in the cold and caloric compensation during forced feeding were as precise for VMH rats eating highly adulterated chow or Noyes pellets contingent on high fixed ratios of lever pressing as for VMH rats eating typical laboratory chow ad lib, even though the former rats at the time maintained weights no greater than intact rats and the latter rats at the time were grossly obese. Furthermore, regulation in the cold or during forced feeding was in general only a little less precise for the rats with lesions than for intact rats. It may be as characteristic of VMH rats that they eat to become lean and remain lean as that they eat to be obese. The diets of both intact and VMH rats in some manner determine the adiposities that rats will defend against caloric challenge.     

Human spatial navigation via a visuo-tactile sensory substitution system

Spatial navigation within a real 3-D maze was investigated to study space perception on the sole basis of tactile information transmitted by means of a 'tactile vision substitution system' (TVSS) allowing the conversion of optical images-collected by a micro camera-into 'tactile images' via a matrix in contact with the skin. The development of such a device is based on concepts of cerebral and functional plasticity, enabling subjective reproduction of visual images from tactile data processing. Blindfolded sighted subjects had to remotely control the movements of a robot on which the TVSS camera was mounted. Once familiarised with the cues in the maze, the subjects were given two exploration sessions. Performance was analysed according to an objective point of view (exploration time, discrimination capacity), as well as a subjective one (speech). The task was successfully carried out from the very first session. As the subjects took a different path during each navigation, a gradual improvement in performance (discrimination and exploration time) was noted, generating a phenomenon of learning. Moreover, subjective analysis revealed an evolution of the spatialisation process towards distal attribution. Finally, some emotional expressions seemed to reflect the genesis of 'qualia' (emotional qualities of stimulation).     

Neuro-cognitive mechanisms of decision making in joint action: a human-robot interaction study

In this paper we present a model for action preparation and decision making in cooperative tasks that is inspired by recent experimental findings about the neuro-cognitive mechanisms supporting joint action in humans. It implements the coordination of actions and goals among the partners as a dynamic process that integrates contextual cues, shared task knowledge and predicted outcome of others’ motor behavior. The control architecture is formalized by a system of coupled dynamic neural fields representing a distributed network of local but connected neural populations. Different pools of neurons encode task-relevant information about action means, task goals and context in the form of self-sustained activation patterns. These patterns are triggered by input from connected populations and evolve continuously in time under the influence of recurrent interactions. The dynamic model of joint action is evaluated in a task in which a robot and a human jointly construct a toy object. We show that the highly context sensitive mapping from action observation onto appropriate complementary actions allows coping with dynamically changing joint action situations.     

Exchange‐based communication training may not consistently facilitate communication in the absence of the requested item

The role of stimulus presence on spontaneous communication was assessed with 3 participants in a nonconcurrent multiple baseline with embedded reversals design. Participants were taught to request 2 highly preferred items. Once mastery criterion was met, test sessions were conducted with stimuli either visible or absent from the room, and request rate was measured. For 2 participants, training produced requests in both the presence and absence of the stimulus. For one participant, however, the presence of the stimulus was necessary to evoke the response. Results suggest that teaching individuals to request items when they are present may not consistently lead to requests when those items are absent.