USING COMPLEX AUDITORY—VISUAL SAMPLES TO PRODUCE EMERGENT RELATIONS IN CHILDREN WITH AUTISM

Six participants with autism learned conditional relations between complex auditory‐visual sample stimuli (dictated words and pictures) and simple visual comparisons (printed words) using matching‐to‐sample training procedures. Pre‐ and posttests examined potential stimulus control by each element of the complex sample when presented individually and emergence of additional conditional relations and oral labeling. Tests revealed class‐consistent performance for all participants following training.     

Stimulus disparity and punisher control of human signal-detection performance

The present experiment examined the effects of varying stimulus disparity and relative punisher frequencies on signal detection by humans. Participants were placed into one of two groups. Group 3 participants were presented with 1:3 and 3:1 punisher frequency ratios, while Group 11 participants were presented with 1:11 and 11:1 punisher frequency ratios. For both groups, stimulus disparity was varied across three levels (low, medium, high) for each punisher ratio. In all conditions, correct responses were intermittently reinforced (1:1 reinforcer frequency ratio). Participants were mostly biased away from the more punished alternative, with more extreme response biases found for Group 11 participants compared to Group 3. For both groups, estimates of discriminability increased systematically across the three disparity levels and were unaffected by the punisher ratios. Likewise, estimates of response bias and sensitivity to the punisher ratios were unaffected by changes in discriminability, supporting the assumption of parameter invariance in the Davison and Tustin (1978) model of signal detection. Overall, the present experiment found no relation between stimulus control and punisher control, and provided further evidence for similar but opposite effects of punishers to reinforcers in signal-detection procedures.     

Shifts in postdiscrimination gradients within a stimulus dimension based on bilateral facial symmetry

A shift in generalization gradients away from S+ and towards stimuli on the opposite end of the stimulus dimension from S- is a well established phenomenon in the laboratory, occurring with humans and nonhumans and with a wide range of stimuli. The phenomenon of gradient shifts has also been observed to have an analogous relationship to a variety of apparent biases in preference observed in the natural environment. One way to examine the validity of such analogies is by examining whether gradient shifts can be observed with complex and naturalistic stimuli. In the present experiment, undergraduates were trained to discriminate between faces that varied in terms of relative bilateral facial symmetry (a stimulus dimension correlated with health and attractiveness). Comparisons were made within subjects, using two sets of images. For both sets, the faces varied from naturally asymmetrical to symmetrical, and S+ was a face equidistant to the two extremes. With one set, S- was the naturally asymmetrical face, and with the other, S- was the symmetrical face. A peak shift was obtained in both conditions, although the effect was clearer in the aggregate than on the level of the individual. Overall, the results are consistent with the view that the processes responsible for gradient shifts in the lab are relevant to judgments made in the natural environment.     

Observing behavior and atypically restricted stimulus control

Restricted stimulus control refers to discrimination learning with atypical limitations in the range of controlling stimuli or stimulus features. In the study reported here, 4 normally capable individuals and 10 individuals with intellectual disabilities (ID) performed two-sample delayed matching to sample. Sample-stimulus observing was recorded with an eye-tracking apparatus. High accuracy scores indicated stimulus control by both sample stimuli for the 4 nondisabled participants and 4 participants with ID, and eye tracking data showed reliable observing of all stimuli. Intermediate accuracy scores indicated restricted stimulus control for the remaining 6 participants. Their eye-tracking data showed that errors were related to failures to observe sample stimuli and relatively brief observing durations. Five of these participants were then given interventions designed to improve observing behavior. For 4 participants, the interventions resulted initially in elimination of observing failures, increased observing durations, and increased accuracy. For 2 of these participants, contingencies sufficient to maintain adequate observing were not always sufficient to maintain high accuracy; subsequent procedure modifications restored it, however. For the 5th participant, initial improvements in observing were not accompanied by improved accuracy, an apparent instance of observing without attending; accuracy improved only after an additional intervention that imposed contingencies on observing behavior. Thus, interventions that control observing behavior seem necessary but may not always be sufficient for the remediation of restricted stimulus control.     

Dynamic Regulation Responding to an External Stimulus: A Differential Equation Model

This study examines the dynamic regulation process responding to an external stimulus. The damped oscillator model has been used to describe this process. However, the model does not allow a nonzero steady state, even though the oscillations may continue and do not necessarily damp toward zero. This study introduces the driven damped oscillator model which has an additional parameter to identify different patterns of the steady state. Three methods, generalized local linear approximation, continuous time structural equation modeling, and analytic solutions of differential equations are provided to estimate model parameters. A simulation study indicates that parameters in the driven damped oscillator model are well recovered. The model is then illustrated using a data set on the daily reports of sales after a sale promotion. Potential applications and possible expansions of this model are also discussed.     

Preferences,Welfare, and the Status-Quo Bias

Preferences play a role in well-being that is difficult to escape, but whatever authority one grants to preferences, their malleability seems to cause problems for any theory of well-being that employs them. Most importantly, preferences appear to display a status-quo bias: people come to prefer what they are likely rather than unlikely to get. I try to do two things here. The first is to provide a more precise characterization of the status-quo bias, how it functions, and how it infects commonly accepted theories of well-being. The second is to give an alternative characterization of an agent's preferences that succeeds in avoiding the status-quo bias.     

Change,Difference, and Orthodox Truthmaker Theory

Call the thesis that, possibly, there are two times, t₁ and t₂, such that everything that exists at t₂ also exists at t₁, but some things that exist at t₁ do not exist at t₂ Temporal Change. Call the thesis that, possibly, there are two worlds, w and v, such that everything that exists at v also exists at w, but some things that exist at w do not exist at v Modal Difference. I argue that if either Temporal Change or Modal Difference is true, then Orthodox Truthmaker Theory—the theory that every truth requires a necessitating truthmaker—is false.     

Valedictory

Contingentism, generally contrasted with law necessitarianism, is the view that the laws of nature are contingent. It is often coupled with the claim that their contingency is knowable a priori. This paper considers Bird's [2001 Bird, Alexander 2001. Necessarily, Salt Dissolves In Water, Analysis 61/4: 267–74.[Crossref], [Web of Science ®] , [Google Scholar], 2002 Bird, Alexander 2002. On Whether Some Laws Are Necessary, Analysis 62/3: 257–70.[Crossref], [Web of Science ®] , [Google Scholar], 2005 Bird, Alexander 2005. Unexpected A Posteriori Necessary Laws of Nature, Australasian Journal of Philosophy 83/4: 533–48.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar], 2007 Bird, Alexander 2007. Nature's Metaphysics: Laws and Properties, Oxford: Clarendon Press.[Crossref] , [Google Scholar]] arguments for the thesis that, necessarily, salt dissolves in water; and it defends his view against Beebee's [2001] and Psillos's [2002 Psillos, Stathis 2002. Salt Does Dissolve In Water, But Not Necessarily, Analysis 62/3: 255–7.[Crossref], [Web of Science ®] , [Google Scholar]] contingentist objections. A new contingentist objection is offered and several reasons for scepticism about its success are raised. It is concluded that certain higher-level laws describing the behaviours of molecular compounds may be necessary due to their dependence on underlying physical laws, and that the modal status of laws of nature cannot be determined a priori, as the structural features of the substances and properties they govern must first be investigated.