EFFECTS OF EQUAL AND UNEQUAL REINFORCER DURATION DURING FUNCTIONAL ANALYSIS

In the functional analysis described by Iwata, Dorsey, Slifer, Bauman, and Richman (1982/1994), reinforcer duration varied across conditions (e.g., brief attention vs. 30 s of escape); this may result in unequal exposure to the establishing operations for aberrant behavior. In this study, we compared the effects of unequal and equal reinforcer duration during a functional analysis. The results showed that reinforcer duration affects the rate of aberrant behavior and may potentially alter functional analysis interpretation.     

A comparison of six methods to estimate thresholds from psychometric functions

There are many ways in which to estimate thresholds from psychometric functions. However, almost nothing is known about the relationships between these estimates. In the present experiment, Monte Carlo techniques were used to compare psychometric thresholds obtained using six methods. Three psychometric functions were simulated using Naka-Rushton and Weibull functions and a probit/logit function combination. Thresholds were estimated using probit, logit, and normit analyses and least-squares regressions of untransformed orz-score and logit-transformed probabilities versus stimulus strength. Histograms were derived from 100 thresholds using each of the six methods for various sampling strategies of each psychometric function. Thresholds from probit, logit, and normit analyses were remarkably similar. Thresholds fromz-score- and logit-transformed regressions were more variable, and linear regression produced biased threshold estimates under some circumstances. Considering the similarity of thresholds, the speed of computation, and the ease of implementation, logit and normit analyses provide effective alternatives to the current “gold standard”—probit analysis—for the estimation of psychometric thresholds.     

Effects on pupil size of manual and verbal indicators of cognitive task fulfillment

A total of20 Ss attempted to generate images to concrete and abstract stimulus words while pupillary activity was continuously photographed. One group (N =5) was required to press a key when an image occurred, a second to describe the image, and a third to press a key as well as describe the image. No overt indicator was required of a fourth group. Results showed that greater dilation occurred during the imagery task than during a control period only in those conditions in which an overt response indicated task fulfillment. Consistent with earlier findings significantly greater dilation occurred to abstract than concrete stimulus words in the key press condition.     

The step method: a new adaptive psychophysical procedure

A new adaptive psychophysical method, the step method, is introduced. Simulations show the method to be less biased and more efficient than constant stimuli or Pentland's adaptive method for fewer than 40 trials. An experiment using discrimination of dot number, however, failed to find any differences among the three methods in either bias or efficiency.     

Reliability of a Measure of Temporal Discounting

The Psychological Record - Participants (N = 17) chose between smaller, immediate and larger, delayed hypothetical money amounts in two laboratory sessions separated by 1 week. The choice procedure...     

TESTIMONY AND SINCERITY

Is there a justified presumption that a speaker is testifying sincerely? Anti‐reductionism about testimony claims that there is, absent reasons to the contrary. Yet why believe this, given the actuality and prevalence of lies and deception? I examine one argument that may be appropriated to meet this challenge, David Lewis's claim that truthfulness is a convention. I argue that it fails, and that the supposition that there is a presumption of sincerity remains unsupported. The failure of Lewis's argument is instructive, however, for it shows us a better way of approaching language use than the standard anti‐reductionist treatment. As speech is an intentional action, so a presumption of the sincerity or otherwise of others' testimony must be explicable in the terms we normally use to explain action.