Predicting and scaling hens' preferences for topographically different responses

Six hens were exposed to several concurrent (second-order) variable-interval schedules in which the response requirements on the alternatives were varied. The response requirements were one key peck versus five key pecks, one key peck versus one door push, and five key pecks versus one door push. Response- and time-allocation ratios undermatched the obtained reinforcement ratios but were well described by the generalized matching law. Time and response bias estimates from two pairs of response requirements were used to predict bias in the third pairing. The predicted values were close to those obtained; this result supports the notion that both numerically and topographically different responses act as constant sources of bias within the generalized matching law. The differences between the response and time biases could be accounted for by the different times needed to complete each response requirement. The results also suggest that the door push is a useful operant for research with domestic hens.     

Stimulus control in the use of landmarks by pigeons in a touch-screen task

Pigeons were tested in a search task on the surface of a monitor on which their responses were registered by a touch-sensitive device. A graphic landmark array was presented consisting of a square outline (the frame) and a colored “landmark.” The unmarked goal, pecks at which produced reward, was located near the center of one edge of the frame, and the landmark was near it. The entire array was displaced without rotation on the monitor from trial to trial. On occasional no-reward tests, the following manipulations were made to the landmark array: (a) either the frame or the landmark was removed; (2) either one edge of the frame or the landmark was shifted; and (3) two landmarks were presented with or without the frame present. On these two-landmark tests, the frame, when present, defined which was the “correct” landmark. When the frame was absent, the “correct” landmark was arbitrarily determined. Results showed that pecks of 2 pigeons were controlled almost solely by the landmark, pecks of 3 were controlled primarily by the landmark but the frame could distinguish the correct landmark, and 1 bird's behavior was controlled primarily by the frame. Stimulus control in this search task is thus selective and differs across individuals. Comparisons to other search tasks and to other stimulus control experiments are made.     

How (not) to evaluate the comparability of MMPI and MMPI-2 profile configurations: a reply to Humphrey and Dahlstrom

Humphrey and Dahlstrom (1995) presented a study on the comparability of MMPI/MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) profiles in which they concluded that "the bases for clinical interpretation derived from the MMPI and MMPI-2 profiles were sufficiently at variance to require different conclusions" [sic] (p. 2). In this brief critique, we identify procedural and data-analytical deficiencies that invalidate Humphrey and Dahlstrom's argument. Their blanket recommendation based on this argument, namely, that clinicians routinely plot both MMPI and MMPI-2 profiles, is unwarranted.     

Resistance to reinforcement change in multiple and concurrent schedules assessed in transition and at steady state

Behavioral momentum theory relates resistance to change of responding in a multiple-schedule component to the total reinforcement obtained in that component, regardless of how the reinforcers are produced. Four pigeons responded in a series of multiple-schedule conditions in which a variable-interval 40-s schedule arranged reinforcers for pecking in one component and a variable-interval 360-s schedule arranged them in the other. In addition, responses on a second key were reinforced according to variable-interval schedules that were equal in the two components. In different parts of the experiment, responding was disrupted by changing the rate of reinforcement on the second key or by delivering response-independent food during a blackout separating the two components. Consistent with momentum theory, responding on the first key in Part 1 changed more in the component with the lower reinforcement total when it was disrupted by changes in the rate of reinforcement on the second key. However, responding on the second key changed more in the component with the higher reinforcement total. In Parts 2 and 3, responding was disrupted with free food presented during intercomponent blackouts, with extinction (Part 2) or variable-interval 80-s reinforcement (Part 3) arranged on the second key. Here, resistance to change was greater for the component with greater overall reinforcement. Failures of momentum theory to predict short-term differences in resistance to change occurred with disruptors that caused greater change between steady states for the richer component. Consistency of effects across disruptors may yet be found if short-term effects of disruptors are assessed relative to the extent of change observed after prolonged exposure.     

Personological evaluation of Clance's Imposter Phenomenon Scale in a Korean sample

The purpose of this study was both to determine if the Impostor Phenomenon (IP) can be reliably and validly assessed in a Korean context and if so, evaluate the construct within the context of Jungian typology and the 5-factor model of personality. A sample of 654 Korean men and women were selected from 4 major Korean cities and administered the Clance Impostor Phenomenon Scale (CIPS; Clance & Imes, 1978) along with the Myers-Briggs Type Indicator (MBTI, Form G; Myers & McCaulley, 1985) and NEO Personality Inventory-Revised (NEO-PI-R; Costa & McCrae, 1992). Results indicated that the CIPS was very reliable, and the pattern of correlates suggested impostors to be introverted types on the MBTI. Results with the NEO-PI-R showed impostors to be very high on neuroticism and low on conscientiousness. This pattern of correlates is similar to other performance-inhibiting constructs such as fear of success and fear of failure. It was argued that IP be construed more as a motivational style than as a distinct clinical syndrome. The IP seems to be less pervasive in Korea than America and these cross-cultural implications were discussed.     

Maximizing internal and external validity in MMPI malingering research: a study of a military population

The authors investigated the effectiveness of various commonly used Minnesota Multiphasic Personality Inventory (MMPI; Hathaway & McKinley, 1943) indices of exaggeration and malingering in detecting suspected malingering in a military sample of 121 enlisted men. To maximize external validity, only men undergoing psychological evaluation were used as participants. Forty-one participants were identified as suspected malingerers through multiple criteria and were contrasted with schizophrenic-spectrum and clinic outpatient groups. To improve internal validity, the 41 suspected malingering participants were asked to retake the test without exaggerating. Results revealed that there were many false positives and fewer, but nonetheless many, false negatives with standard malingering indices. It appeared that the Gough Dissimulation scale (Gough, 1947) might hold the most promise as a measure of malingering, but other scales are also useful. Individual comparisons between different samples and implications for MMPI-2 (Butcher et al., 1989) are presented.     

A transformation of self-discrimination response functions in accordance with the arbitrarily applicable relations of sameness, more than, and less than

In Experiment 1, 2 experimental subjects were given pretraining of nonarbitrary relations that brought their responses under the control of four contextual stimuli; same, opposite, more than, and less than. One control subject was not exposed to this pretraining. The 2 pretrained subjects and the 3rd nonpretrained subject then received training in six arbitrary relations, the following four relations being the most critical: same/A1-B1, same/A1-C1, less than/A1-B2, more than/A1-C2. All 3 subjects were then tested for seven derived relations, the following three relations being the most important: same/B1-C1, more than/B1-C2, less than/B1-B2. The 2 pretrained subjects, but not the nonpretrained subject, showed the derived relations. One of the stimuli (B1) from the relational network and two novel stimuli (X1 and X2) were then used to train three different self-discrimination responses on three complex schedules of reinforcement. That is, all 3 subjects were trained to pick X1 if they had not emitted a response, to pick B1 if they had emitted one response only, and to pick X2 if they had emitted two responses only. The 2 pretrained subjects, but not the nonpretrained subject, showed the predicted transformation of self-discrimination response functions in accordance with the relations of sameness, more than, and less than (i.e., no response, pick B2; one response only, pick C1; and two responses only, pick C2). In Experiment 2, 2 new subjects were employed, and the arbitrary relational training and testing phases were modified to control for a procedural artifact that may have contributed to the results of the first experiment. Experiment 2 replicated the findings of Experiment 1. The pattern of results support the utility of a relational frames approach to understanding derived stimulus relations.     

Biasing the pacemaker in the behavioral theory of timing

In the behavioral theory of timing, pacemaker rate is determined by overall rate of reinforcement. A two-alternative free-operant psychophysical procedure was employed to investigate whether pacemaker period was also sensitive to the differential rate of reinforcement. Responding on a left key during the first 25 s and on a right key during the second 25 s of a 50-s trial was reinforced at variable intervals, and variable-interval schedule values during the two halves of the trials were varied systematically. Responding on the right key during the first 25 s and on the left key during the second 25 s was not reinforced. Estimates of pacemaker period were derived from fits of a function predicted by the behavioral theory of timing to right-key response proportions in consecutive 5-s bins of the 50-s trial. Estimates of pacemaker period were shortest when the differential reinforcer rate most strongly favored right-key responses, and were longest when the differential reinforcer rate most strongly favored left-key responses. The results were consistent with the conclusion that pacemaker rate is influenced by relative reinforcer rate.     

Self-control and impulsiveness in children and adults: Effects of food preferences

Experiment 1 used 6 preschool boys and Experiment 2 used 6 adult women to explore the effects of food preference on humans' choice in self-control paradigms. The boys showed a higher proportion of responses for more delayed, larger reinforcers (a measure of self-control) when those choices resulted in receipt of the most preferred food compared to when those choices resulted in the least preferred food. Further, the boys chose the less delayed, smaller reinforcers significantly more often when only those choices, as opposed to both choices, resulted in the most preferred food. Conversely, they chose the more delayed, larger reinforcers significantly more often when only those choices, as opposed to both choices, resulted in the most preferred food. Finally, the women demonstrated significantly less sensitivity to reinforcer amount relative to sensitivity to reinforcer delay (another measure of self-control) when they had a higher preference for the juice received as the less delayed, smaller reinforcer than for the juice received as the more delayed, larger reinforcer. Together, the results show that subjects' food preferences can influence self-control for food reinforcers.     

Achieving Coordination in Prehension: Joint Freezing and Postural Contributions

The focus of the present study was on the intersegmental relationships that emerge when both task and oganismic constraints are imposed upon the coordination system. Seven right-handed subjects were required to reach and grasp a cup (hand transport phase) and place it on a designated target (cup transport phase), using either their preferred or nonpreferred hand. The kinematics of the movement were examined as a function of task (grasping a full cup versus grasping an empty one) and organismic (preferred or nonpreferred hand) constraints. During the hand transport phase, a task constraint effect was revealed through an increase in the low-velocity phase for the full cup condition. This constraint coexisted with a decrease in angular motion of the shoulder and elbow joints, indicating subjects reduced the number of variables to be independently controlled in the final homing-in stage of the movement. Accompanying this decrease in angular change was an increase in the displacement of the trunk. During the cup transport phase, the trunk was shown to contribute significantly more to the movement in the full cup condition and for the left hand movements, thereby increasing the stability of the movement system. These findings are in agreement with Bernstein's (1967) notion of fixating parts of the body as an initial solution to a movement problem, and they lend support to the concept of a proximodistal organization of coordination.