The power law as behavioral illusion: reappraising the reappraisals.

Marken and Shaffer (Exp Brain Res 235:1835-1842, 2017) have argued that the power law of movement, which is generally thought to reflect the mechanisms that produce movement, is actually an example of what Powers (Psychol Rev 85:417-435, 1978) dubbed a behavioral illusion, where an observed relationship between variables is seen as revealing something about the mechanisms that produce a behavior when, in fact, it does not. Zago et al. (Exp Brain Res.

Systematic bias in predictions of new drugs' budget impact: analysis of a sample of recent US drug launches.

Objective: Expectations about the budget impact of new drug launches may affect payer behavior and ultimately consumer costs. Therefore, we evaluated the accuracy of pre-launch US budget impact estimates for a sample of new drugs.

Methods: We searched for publicly available budget impact estimates made pre-launch for drugs approved in the US from 1 September 2010 to 1 September 2015 and compared them to actual sales.

The power law of movement: an example of a behavioral illusion.

The curved movements produced by living organisms follow a power law where the velocity of movement is a power function of the degree of curvature through which the movement is made. The exponent of the power function is close to either 1/3 or 2/3 depending on how velocity and curvature are measured. This power law is thought to reflect biological and/or kinematic constraints on how organisms produce movements.

Control blindness: Why people can make incorrect inferences about the intentions of others.

There is limited evidence regarding the accuracy of inferences about intention. The research described in this article shows how perceptual control theory (PCT) can provide a "ground truth" for these judgments. In a series of 3 studies, participants were asked to identify a person's intention in a tracking task where the person's true intention was to control the position of a knot connecting a pair of rubber bands.

Catching objects thrown to oneself: Testing control strategies for object interception in a novel domain.

A considerable amount of research has been performed to determine the strategies people use to intercept moving objects. Much of this research has been done using target objects such as baseballs and Frisbees that are launched to people from distances ranging from 10 m to 50 m. This research has qualified the range of domains in which each strategy is effective, but there is still controversy regarding which strategy has the most general application.

Understanding the Change Process Involved in Solving Psychological Problems: A Model-based Approach to Understanding How Psychotherapy Works.

Unlabelled: A review of the literature on psychotherapy suggests that improvements in effectiveness, efficiency and accessibility have been hampered by a lack of understanding of how psychotherapy works. Central to gaining such understanding is an accurate description of the change process that occurs when someone solves a psychological problem. We describe the Perceptual Control Theory (PCT) model of human functioning, which can be used to understand the nature of psychological problems and how they are solved.

Motor control as the control of perception.

This paper describes a test of Perceptual Control Theory (PCT), which views motor control as part of a process of controlling perceptual inputs rather than motor outputs. Sixteen undergraduate students (M age = 19.9 yr.

Making inferences about intention: perceptual control theory as a "theory of mind" for psychologists.

Theory of Mind (ToM) assumes that humans and possibly other primates understand behavior in terms of inferences about intentions. While there is evidence that primates make such inferences, little attention has been paid to the question of their validity. In order to answer this question it is necessary to know the true intentions underlying behavior.

Testing for controlled variables: a model-based approach to determining the perceptual basis of behavior.

Perceptual control theory (PCT) views behavior as being organized around the control of perceptual variables. Thus, from a PCT perspective, understanding behavior is largely a matter of determining the perceptions that organisms control-the perceptions that are the basis of the observed behavior. This task is complicated by the fact that very often the perceptions that seem to be the obvious basis of some behavior are not.

Chasin' choppers: using unpredictable trajectories to test theories of object interception.

Three theories of the informational basis for object interception strategies were tested in an experiment where participants pursued toy helicopters. Helicopters were used as targets because their unpredictable trajectories have different effects on the optical variables that have been proposed as the basis of object interception, providing a basis for determining the variables that best explain this behavior. Participants pursued helicopters while the positions of both pursuer and helicopter were continuously monitored.

Taking purpose into account in experimental psychology: testing for controlled variables.

Experimental research in psychology is based on a causal model--the General Linear Model (GLM)--that assumes behavior has causes but not purposes. Powers (1978) used a control theory analysis to show that the results of psychological experiments based on such a model can be misleading if the organisms being studied are purposeful (control) systems. In the same paper, Powers presented evidence that organisms are such systems.

When causality does not imply correlation: more spadework at the foundations of scientific psychology.

Experimental research in psychology is based on an open-loop causal model which assumes that sensory input causes behavioral output. This model was tested in a tracking experiment where participants were asked to control a cursor, keeping it aligned with a target by moving a mouse to compensate for disturbances of differing difficulty. Since cursor movements (inputs) are the only observable cause of mouse movements (outputs), the open-loop model predicts that there will be a correlation between input and output that increases as tracking performance improves.

Optical trajectories and the informational basis of fly ball catching.

D. M. Shaffer and M.

Functional characteristics of commercial ambulatory electronic prescribing systems: a field study.

Objective: To compare the functional capabilities being offered by commercial ambulatory electronic prescribing systems with a set of expert panel recommendations.

Design: A descriptive field study of ten commercially available ambulatory electronic prescribing systems, each of which had established a significant market presence. Data were collected from vendors by telephone interview and at sites where the systems were functioning through direct observation of the systems and through personal interviews with prescribers and technical staff.

Recommendations for comparing electronic prescribing systems: results of an expert consensus process.

Commercially available electronic prescribing systems may differ in their effects on patients' health outcomes and on patients' ability to manage costs. An expert panel convened to recommend specific features that would enable electronic prescribing systems to advance these goals. The panel authored sixty recommendations and rated each using a modified Delphi process.

A conceptual framework for evaluating outpatient electronic prescribing systems based on their functional capabilities.

Objective: Electronic prescribing (e-prescribing) may substantially improve health care quality and efficiency, but the available systems are complex and their heterogeneity makes comparing and evaluating them a challenge. The authors aimed to develop a conceptual framework for anticipating the effects of alternative designs for outpatient e-prescribing systems.

Design: Based on a literature review and on telephone interviews with e-prescribing vendors, the authors identified distinct e-prescribing functional capabilities and developed a conceptual framework for evaluating e-prescribing systems' potential effects based on their capabilities.

Error in skilled performance: a control model of prescribing.

A control model of skilled performance is proposed as a framework for understanding why prescribing errors occur at a particular rate. Model error rate depends on skill level, system design characteristics, the range of different types of prescriptions that are produced and the time available to complete each prescription. The parameters of the model can be adjusted so it produces error rates that are quantitatively equal to those found in studies of the incidence of different types of prescribing error.

Perceptual organization of behavior: a hierarchical control model of coordinated action.

The behavior of individual subjects is compared with a hierarchical control system model of behavioral organization. Subjects varied the position of two control handles simultaneously to keep the distance constant between two pairs of lines. Three variations on this basic experiment that illustrate some fundamental properties of coordinated action are shown: first, how independent actions, compensating for unpredictable and undetectable disturbances, can produce a single behavioral result; second, how the ability to produce a particular result is maintained when the connection between action and result is changed; and third, how two independent outputs can appear to be related as coordinative structures when one output disturbs a result being controlled by the other.