Determinants of word fragment completion

A current debate in the memory literature concerns the validity of word fragment completion (WFC) as a test of implicit memory. It has been claimed that language variables exert a strong influence on the task, and that the task reflects memory only to a small extent (Hintzman & Hartry, 1990). For these reasons, the use of contingency analyses of recognition and WFC performance as a means of studying underlying memory processes has been criticized. The present study addressed this issue by examining the influence of language variables on completion of a set of computer generated single-solution fragments of Swedish words (Olofsson & Nyberg, 1992). It was found that language variables indeed had a large effect on completion performance, and that priming only accounted for a small portion of variance in the task. It is therefore suggested that the method of triangulation should be employed for contingency analyses involving WFC.     

A Completeness Proof for a Logic with an Alternative Necessity Operator

We show the completeness of a Hilbert-style system LK defined by M. Valiev involving the knowledge operator K dedicated to the reasoning with incomplete information. The completeness proof uses a variant of Makinson's canonical model construction. Furthermore we prove that the theoremhood problem for LK is co-NP-complete, using techniques similar to those used to prove that the satisfiability problem for propositional S5 is NP-complete.     

Distractor selection ratios

A latent variable representation for multiple-choice item and option characteristic curves is presented. Under standard assumptions of conditional independence of item responses and monotonicity of item characteristic curves, a criterion for distractors is proposed based on distractor selection ratios. A connection is made between the proposed criterion and the theory of individual choice behavior, providing new insight. The main results allow for the testing of the criterion from observable data without first specifying a parametric form for the characteristic curves. A series of examples apply the method.     

Mechanics of the animate.

Behavior is treated as basic physics. Dimensions are identified and their transformations from physical specification to axes in behavioral space are suggested. Responses are treated as action patterns arrayed along a continuum of activation energy. Behavior is seen as movement along a trajectory through this behavior space. Incentives or reinforcers are attractors in behavior space, at the centers of basins of lowered potential. Trajectories impinging on such basins may be captured; repeated capture will warp the trajectory toward a geodesic, a process called conditioning. Conditioning is enhanced by contiguity, the proximity between the measured behavior and the incentive at the end of the trajectory, and by contingency, the depth of the trajectory below the average level of the potential energy landscape. Motivation is seen as the potential of an organism for motion under the forces impinging on it. Degree of motivation is characterized by the depth of the potential field, with low motivation corresponding to a flat field and a flat gradient of activation energy. Drives are the forces of incentives propagated through behavior space. Different laws for the attenuation of drive with behavioral distance are discussed, as is the dynamics of action. The basic postulate of behavior mechanics is incentive-tracking in behavior space, the energy for which is provided by decreases in potential. The relation of temporal gradients to response differentiation and temporal discrimination is analyzed. Various two-body problems are sketched to illustrate the application of these ideas to association, choice, scalar timing, self-control, and freedom.     

Autoshaping in the rat: Effects of omission on the form of the response

Two experiments were conducted to investigate the effect of an omission contingency on behavior related to and characterizing autoshaped lever contacts in the rat. In Experiment I an omission contingency imposed on autoshaped lever contacts forceful enough to produce a press (.078N) resulted in a significant decrease in lever presses, but had no effect on frequency of lever touches (contacts of insufficient force to produce a press) or rate of food tray entry during lever presentation. In contrast, rats which received a similar number of lever-food pairings, but whose behavior had no programmed consequences (yoked control subjects), showed an increase in lever press rate, a significant decrease in rate of food tray entry, and no change in rate of lever-touches. In Experiment II, the effect of a similar omission contingency on the topography of lever contact responses was investigated. Prior to omission training subjects contacted the lever primarily by pawing it. Following omission training this behavior was suppressed, with a subsequent increase in lever contacts characterized as nosing. Yoked control subjects showed no significant changes in lever contact topography. The results indicate that (1) an omission contingency does not simply eliminate wholesale those topographies which incur the contingency but produces subtle adaptive changes in lever contact topography; and (2) the nature of the autoshaped response in the rat does not appear to be rigid enough to depend solely upon the nature of the unconditioned stimulus or the conditioned stimulus, but can also be determined by the relationships existing between the animal's behavior and these stimuli.     

Response Stereotypy in Humans Maintained by Response-Contingent Events

The present study examined stereotyped behaviors developed during human performances that were generated by response-dependent intermittent schedules of reinforcement. Thirty university students were assigned to either fixed-interval 30-s or fixed-ratio 30-s schedules in which points or monetary reinforcers were produced only by presses on the number keys of a 41-key computer keyboard. Behavior patterns developed by all subjects were classified into four categories: optimal, random, unique, and general stereotypes. The general stereotypes category was further subdivided into five idiosyncratic types: connection, order, shift, repeat, and restriction. Analysis of the data demonstrated the role of contiguity: Whatever behavior happened to precede reinforcers was repeated even though reinforcers did not depend on that behavior. These findings support the argument that much of idiosyncratic and stereotyped human behavior is produced and maintained by contingencies of reinforcement, rather than schedule-induced or adjunctive behavior.     

Incongruous stimulus pairing and conditional discrimination training: effects on relational responding

In Experiment 1, 5 subjects were exposed to a stimulus-pairing procedure in which two nonsense syllables, identified by a letter-number code as A1 and C2, each predicted the onset of a sexual film clip, and the nonsense syllables A2 and C1 each predicted the onset of a nonsexual film clip. Subjects were then exposed to a matching-to-sample test in which the nonsense syllables A1 and A2 were presented as sample stimuli and C1 and C2 were presented as comparison stimuli and vice versa (i.e., C stimuli as samples and A stimuli as comparisons). All subjects matched A1 with C2 and A2 with C1. Subjects were then trained on the conditional discriminations A1-B1, A2-B2, B1-C1, B2-C2, after which the matching-to-sample test was again administered. All subjects continued to match A1 with C2 and A2 with C1 in accordance with the earlier stimulus-pairing contingencies. An additional 5 subjects were exposed first to conditional discrimination training and testing before being exposed to the incongruous stimulus pairing and matching-to-sample testing. Under these conditions, 4 of the 5 subjects always matched A1 with C1 and A2 with C2. Experiment 2 replicated Experiment 1, except that a matching-to-sample test was not administered following the initial training procedure. Under these conditions, matching-to-sample test performances were controlled by the contingencies that had immediately preceded the test. Experiment 3 indicated that initial matching-to-sample test performances were unlikely to change, even after repeated exposure to incongruous training and testing. Experiment 4 demonstrated that pretraining with unrelated stimulus sets increased the sensitivity of matching-to-sample test performances to incongruous contingencies when they were similar in format to those arranged during pretraining. These data may have implications for a behavior-analytic interpretation of attitude formation and change.     

DEGREE OF CONSTRUCTED-RESPONSE INTERACTION IN COMPUTER-BASED PROGRAMMED INSTRUCTION

This investigation evaluated the importance of frequent responding in computer-based programmed instruction. Instructional computer programs that taught the use of an authoring language were administered to 155 undergraduate college students. One group experienced frequent (dense) situations requiring them to supply key components of the subject taught. A second group experienced half as many response requirements, and a third “passive” group simply tapped any key to progress. To control for time in contact with presentations, individuals in a fourth group were yoked to the members of the high-density requirement group. Statistically significant differences on both posttest and application performances indicated that students who experienced the high density of overt response contingencies scored the best and the passive group score the worst. The yoked control revealed that time on task alone could not account for the superior performance of students in the high-density group. Results suggest that inclusion of a high rate of constructed-response contingencies within instructional computer programs increases performance.     

RELIGION AND THE THEORIES OF SCIENCE: A RESPONSE TO BARBOUR

Abstract. This paper offers a detailed response to “Religion and the Theories of Science” in Barbour's Gifford Lectures I. Topics include: complementarity, indeterminacy, parts and wholes, and Bell's theorem in quantum theory; metaphysical issues raised by relativity theory and thermodynamics, principally the problem of temporality and “top-down” versus “bottom—up” causality; design arguments and the origins of the universe in astronomy and creation; and God's action in the context of evolution and continuing creation. Areas of agreement and disagreement between Barbour and myself over philosophical and theological implications are presented, and endnotes indicate further areas of conversation.