Four probability-preserving properties of inferences

Different inferences in probabilistic logics of conditionals preserve the probabilities of their premisses to different degrees. Some preserve certainty, some high probability, some positive probability, and some minimum probability. In the first case conclusions must have probability 1 when premisses have probability 1, though they might have probability 0 when their premisses have any lower probability. In the second case, roughly speaking, if premisses are highly probable though not certain then conclusions must also be highly probable. In the third case conclusions must have positive probability when premisses do, and in the last case conclusions must be at least as probable as their least probable premisses. Precise definitions and well known examples are given for each of these properties, characteristic principles are shown to be valid and complete for deriving conclusions of each of these kinds, and simple trivalent truthtable tests are described for determining which properties are possessed by any given inference. Brief comments are made on the application of these results to certain modal inferences such as Jones may own a car, and if he does he will have a driver's license. Therefore, he may have a driver's license.     

Factors in the modification by isolation of electroconvulsive shock-produced retrograde amnesia in the rat.

It has been demonstrated that placing rats in a sensory-restricted environment during the electronconvulsive shock- (ECS) retention interval following 1-trial appetitive learning will prevent or eliminate ECS-produced retrograde amnesia. The first study replicated this finding with a 1-trial aversive learning task, indicating that this effect is not task specific. The second study attempted to determine whether illumination or the restricted environment was the crucial factor in this penomenon. Rats placed in the light during the ECS-retention interval, whether restricted or in the colony, demonstrated retrograde amnesia after ECS. However, rats left in the dark during this interval demonstrated little, if any, retention deficit particularly if this condition was combined with sensory isolation. These studies further indicate that manipulation of the general environment of the animal after ECS can alter ECS-produced retention losses.     

Competitive fighting in the rat.

Competitive fighting was obtained in pairs of like-sexed laboratory rats by placing a single piece of food into the food hopper following 48 hr. of food deprivation. The fighting was characterized by offensive sideways posture, full aggressive posture, and bite and kick attack. Tests were conducted at 110-120 days of age on pairs of animals that had been housed together since weaning. Fighting was more frequent in pairs consisting of nonlittermates than in pairs of littermates, and it was equally frequent in male and female pairings. Probability of fighting was enhanced by prior experience with food deprivation, and attack was most often initiated by the heavier animal of the pair.     

Voice onset and articulatory constriction requirements in a speech segment and their relation to the amount of stuttering adaptation

This study evaluated the hypothesis that the amount of stuttering adaptation increases as the number of requirements for the prompt onset of phonation and complete articulatory constriction across passages decreases. To test this prediction, three special reading passages were constructed. The number of requirements for the quick initiation of phonation and complete articulatory constriction decreased from passages I to II to III. Eleven stutterers read each passage five times. Of these individuals, seven exhibited the well-known adaptation effect on all three selections. However, adaptation increased significantly from passage I to II to III. Among the remaining four subjects, three failed to adapt on passage I which contained the greatest number of requirements for the prompt onset of phonation and complete articulatory constrictions. These results were interpreted as supporting the hypothesis under test.     

Learning from negative outcomes in stuttering therapy: I. Getting off on the wrong foot

Considering the long history of research into stuttering, it is surprising that so little time has been devoted to the study of factors that contribute to the success of therapy. Even less attention has been devoted to uncovering forces that promote poor treatment outcomes. In this article and the companion piece that follows it, an attempt has been made to delineate what may prove to be predictors of unsuccessful therapy. In this first of the two articles, the focus in on the identification of patient, extraclinical, and clinician variables that could act to negate progress during the establishment phase of treatment.     

Depression: avoidance learning and physiological correlates in clinical and analog populations

The behavioral and physiological components of depression were investigated in two experiments comparing eight student and seven non-student depressed females with an equal number of students and non-student controls on avoidance tasks and electrodermal responsivity to an aversive audiotape. Avoidance behavior was assessed in both active and passive paradigms where the correct response or response suppression, respectively, function to avoid a noxious buzzer. Physiological activity and reactivity were compared using measurements of skin resistance level and SRR fluctuations during resting and aversive tape periods. It was found that the depressed groups showed inferior active and superior passive avoidance learning as compared to controls. Depressed subjects were also more emotionally responsive (showed a greater number of SRR) during presentation of the audiotape. A passive avoidance model for depression is suggested for the explanation of the phenomena observed. A distinct difference was also found between student and non-student populations. The utility of college student analogs for depression is questioned.