Differentiating the differential rotation effect

As an observer views a picture from different viewing angles, objects in the picture appear to maintain their orientation relative to the observer. For instance, the eyes of a portrait appear to follow the observer as he or she views the image from different angles. We have explored this rotation effect, often called the Mona Lisa effect. We report three experiments that used portrait photographs to test variations of the Mona Lisa effect. The first experiment introduced picture displacements relative to the observer in directions beyond the horizontal plane. The Mona Lisa effect remained robust for vertical and/or diagonal observer displacements. The experiment also included conditions in which the portrait had averted gaze directions. An interaction between picture position relative to the observer and gaze direction was found. The second experiment followed up on very pronounced individual differences, suggesting that the Mona Lisa effect is even stronger than it should be for half of all observers (over-rotators). These individual differences do not correlate with any of the standard personality dimensions (Big Five) or with spatial intelligence. In the third experiment, we extended the experiment to virtual 3D heads using the same gaze directions and picture displacements as for the 2D portrait faces. Besides the picture displacements relative to the observer, we also added observer displacements relative to the picture. 3D pictures showed the Mona Lisa effect, but to a smaller extent than did 2D pictures.     

Behavioral contrast as differential time allocation

In Experiment I, hooded rats were exposed to multiple variable-interval schedules of reinforcement in which manipulanda and reinforcement magazines at opposite ends of the experimental chamber were associated with the different components. Time allocated to each component was measured by recording the time spent by the subject in the appropriate half of the chamber. Positive behavioral contrast was observed for the comparison between multiple variable-interval 30-second variable-interval 30-second and multiple variable-interval 30-second variable-interval 90-second conditions for both response frequency and time allocation measures, but not for mean local response rate (response frequency per time allocated to a component). In Experiment II, rats were exposed to multiple variable-time schedules in which reinforcement was response independent. Time allocated to each component was measured for two conditions, multiple variable-time 30-second variable-time 30-second and multiple variable-time 30-second variable-time 90-second. Positive behavioral contrast of time allocation was exhibited. The results indicated that time allocation was differentially sensitive to changes in reinforcement probability, and that behavioral contrast may result from the differential allocation of time to the different components of the multiple schedule.     

Time errors and differential sensation weighting

Sixteen pairs of successive tones, with different amplitude combinations, were presented with 16 combinations of tone duration and interstimulus interval. A separate group of 12 subjects was assigned to each presentation condition and made comparative loudness judgments for each of the pairs. Perceived within-pair loudness differences were scaled by a Thurstonian method using the subjective width of the "equal" category as the unit. The scale differences were well described by weighted linear combinations of the sensation magnitudes of the tones in the pairs. The time error can be regarded as an effect of this differential weighting. For the longer interstimulus intervals, the weight of the second tone was the greater, causing the usual inverse relation between time error and stimulus intensity level. For the shorter interstimulus intervals, these effects were reversed. An analysis of the pattern of weights led to the development of two models, one of which is a generalization of Michels and Helson's time error model. The weights could be interpreted as reflecting the differential efficiency of the loudness information from the two compared stimuli.     

Safety,sensitivity and differential support

Synthese - The paper argues against Sosa’s claim that sensitivity cannot be differentially supported over safety as the right requirement for knowledge. Its main contention is that, although...     

Errorless discrimination established by differential autoshaping

In Experiment I, pigeons exposed to a differential autoshaping procedure pecked a key in the presence of the stimulus associated with reinforcement but did not peck, or pecked infrequently, in the presence of the stimulus associated with nonreinforcement. In Experiment II, pigeons were exposed to a differential autoshaping procedure in which one stimulus was associated with reinforcement and two stimuli were associated with nonreinforcement. The birds initially responded in the presence of one stimulus associated with nonreinforcement but never responded in the presence of the second stimulus associated with nonreinforcement. They were subsequently exposed to an autoshaping procedure in which reinforcement followed both these stimuli. The number of stimulus-reinforcement pairings required to establish pecking in the presence of the stimulus during which responses had not previously occurred suggested that such stimuli are inhibitory. These findings have implications for autoshaping, errorless discrimination, inhibition, and theories of discrimination byproducts.     

Adverse effects of differential parental attention

In two independent parent training projects (Kansas and Mississippi), mothers of deviant young children were observed to follow almost all child behaviors with attention. The mothers were then trained to use differential attention procedures to increase their child's appropriate behaviors and to decrease deviant behaviors. Contrary to expectations, the differential attention procedure produced substantial increases in deviant behavior for four of the children. This adverse effect was maintained over many sessions and was replicated in single organism, reversal designs. A fifth child showed no change. A sixth child showed some improvement. However, this effect was not recovered in a second application of differential attention, and the child became worse. The results underline the importance of subject generality in applied behavior analysis and strongly suggest that service programs using operant techniques must carefully evaluate their effects on behavior.     

I-Level: a differential counseling system

This article suggests that the counselor, the client, and the counseling strategies employed must be systematically examined in order to maximize the effectiveness of counseling. The authors introduce the Interpersonal Maturity Level Typology as a vehicle through which this can be accomplished. They describe client and counselor types, present the notion of matching, and recommend differential counseling strategies.     

Rate differential reinforcement in monkey manipulation

A set of four manipulanda were presented to four Cebus monkeys, individually, and later in pairs. Step 1 provided an estimate of each S's probability of operating each item, while Step 2 determined whether pairing the items would disturb the ordinal relations among individual response probabilities. Both procedures provided information necessary for testing the assumption that a reinforcer is simply a contingent response whose independent probability of occurrence is greater than that of the associated instrumental response. Step 3 tested this assumption by again presenting pairs of items, but with one locked and its operation made contingent upon operation of the free item of the pair. The four Ss differed markedly in the extent to which the items produced different independent response probabilities, and correspondingly, in the extent to which the contingent pairs subsequently produced reinforcement. Confirmation of the present assumptions came primarily from one S, which differed substantially on the individual items, and showed five cases of reinforcement, all in the predicted direction. Further, reinforcement was shown by an increase in both contingency and extinction sessions. Finally, the response of intermediate probability reinforced the response of least, but not the one of greatest, probability, indicating that a reinforcer cannot be identified absolutely, but only relative to the base response.     

Personal computer software for teaching differential psychodiagnostics

The third edition of theDiagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1980), outlines for the student what symptoms to consider when attempting to arrive at an accurate differential diagnosis of eight broad psychiatric categories. This paper describes a program developed to instruct a medical or graduate student in the science of such decision making.     

Preference after training with differential changeover delays

Pigeons were trained on a multiple schedule in which each component consisted of concurrent variable-interval (VI) 30-s VI 60-s schedules. The two components of the multiple schedule differed only in terms of the changeover delays (COD): For one component short CODs were employed, and in the second component long CODs were used. After approximate matching was obtained in each component, probe tests involving new combinations of stimuli were presented (e.g., the VI 30-s schedule from each component) to determine how the different CODs affected preference. Despite shorter CODs producing higher changeover rates, the COD value had no systematic effect on preference on the probe trials. However, differences in reinforcement rate always produced preference for the schedule with the higher reinforcement rate. The results thus show that the the pattern of changeover behavior per se is not a critical determinant of choice in the probe-trial procedure.     

British semantic differential responses on world powers

Investigating stereotypes associated with world powers, 28 men and 28 women at a British university rated 24 world powers using the semantic differential. Significance tests show the relationship of the powers to concepts assumed to measure the Evaluative, Potency, and Activity factors. Three-dimensional models show the relative positioning by men and by women. Results indicate (1) general agreement between men and women; (2) superpowers close to BAD and STRONG; (3) countries associated with war and strife closer to BAD, WEAK, and PASSIVE. Comparisons were made with an American sample. The need for doing further stereotype studies over time was stressed.     

Evaluating methods for approximating stochastic differential equations

Models of decision making and response time (RT) are often formulated using stochastic differential equations (SDEs). Researchers often investigate these models using a simple Monte Carlo method based on Euler's method for solving ordinary differential equations. The accuracy of Euler's method is investigated and compared to the performance of more complex simulation methods. The more complex methods for solving SDEs yielded no improvement in accuracy over the Euler method. However, the matrix method proposed by Diederich and Busemeyer (2003) yielded significant improvements. The accuracy of all methods depended critically on the size of the approximating time step. The large (∼10 ms) step sizes often used by psychological researchers resulted in large and systematic errors in evaluating RT distributions.