Concurrent nonindependent fixed‐ratio schedules of alcohol self‐administration: Effects of schedule size on choice

Choice behavior was studied under concurrent nonindependent fixed‐ratio fixed‐ratio (nFR) schedules of reinforcement, as these schedules result in frequent changeover responses. With these schedules, responses on either operandum count toward the completion of the ratio requirements of both schedules. Five monkeys were subjects, and two pairs of liquid reinforcers were concurrently available: 16% (w/v) and 0% ethanol or 16% and 8% ethanol. For each pair of reinforcers, the nFR sizes were systematically altered across sessions while keeping the schedule size equal for both liquids. Responding varied as a function of reinforcer pair and nFR size. With the 16% and 0% pair, higher response rates were maintained by 16% and were an inverted U‐shape function of nFR size. With 16% and 8%, a greater number of responses initially occurred on the schedule that delivered 8% ethanol. However, as nFR size increased, preference reversed such that responses that delivered 16% ethanol were greater. When the nFR size was subsequently decreased, preference reverted back to 8%. Number of responses emitted per delivery was a dependent variable and, in behavioral economic terms, was the price paid for each liquid delivery. With 16% and 0%, changeover responses initially increased and then decreased as schedule size became larger. In contrast, with the 16% and 8% pair, changeover responses increased directly with schedule size. Responding under nFR schedules is sensitive to differences in reinforcer magnitude and demonstrates that relative reinforcing effects can change as a function of schedule size.     

On sample size calculation for 2×2 fixed‐effect ANOVA when variances are unknown and possibly unequal

The factorial 2 × 2 fixed‐effect ANOVA is a procedure used frequently in scientific research to test mean differences between‐subjects in all of the groups. But if the assumption of homogeneity is violated, the test for the row, column, and the interaction effect might be invalid or less powerful. Therefore, for planning research in the case of unknown and possibly unequal variances, it is worth developing a sample size formula to obtain the desired power. This article suggests a simple formula to determine the sample size for 2 × 2 fixed‐effect ANOVA for heterogeneous variances across groups. We use the approximate Welch t test and consider the variance ratio to derive the formula. The sample size determination requires two‐step iterations but the approximate sample sizes needed for the main effect and the interaction effect can be determined separately with the specified power. The present study also provides an example and a SAS program to facilitate the calculation process.     

New heterogeneous test statistics for the unbalanced fixed‐effect nested design

When the underlying variances are unknown or/and unequal, using the conventional F test is problematic in the two‐factor hierarchical data structure. Prompted by the approximate test statistics (Welch and Alexander–Govern methods), the authors develop four new heterogeneous test statistics to test factor A and factor B nested within A for the unbalanced fixed‐effect two‐stage nested design under variance heterogeneity. The actual significance levels and statistical power of the test statistics were compared in a simulation study. The results show that the proposed procedures maintain better Type I error rate control and have greater statistical power than those obtained by the conventional F test in various conditions. Therefore, the proposed test statistics are recommended in terms of robustness and easy implementation.     

Comparing fixed‐amount and progressive‐amount DRO Schedules for tic suppression in youth with chronic tic disorders

Chronic tic disorders (CTDs) involve motor and/or vocal tics that often cause substantial distress and impairment. Differential reinforcement of other behavior (DRO) schedules of reinforcement produce robust, but incomplete, reductions in tic frequency in youth with CTDs; however, a more robust reduction may be needed to affect durable clinical change. Standard, fixed‐amount DRO schedules have not commonly yielded such reductions, so we evaluated a novel, progressive‐amount DRO schedule, based on its ability to facilitate sustained abstinence from functionally similar behaviors. Five youth with CTDs were exposed to periods of baseline, fixed‐amount DRO (DRO‐F), and progressive‐amount DRO (DRO‐P). Both DRO schedules produced decreases in tic rate and increases in intertic interval duration, but no systematic differences were seen between the two schedules on any dimension of tic occurrence. The DRO‐F schedule was generally preferred to the DRO‐P schedule. Possible procedural improvements and other future directions are discussed.     

The relationship between confidence and self-concept — Towards a model of response confidence

According to Stankov [Stankov, L. (2000). Complexity, metacognition and fluid intelligence. Intelligence, 28, 121–143.] response confidence in cognitive tests reflects a trait on the boundary of personality and abilities. However, several studies failed in relating confidence scores to other known traits, including self-concept. A model of response confidence is proposed which predicts that confidence judgements do reflect self-concept, but only to the extent that they do not reflect a calibration process based on task-inherent cues. In the current study, 101 students completed various tests of cognitive abilities and skills as well as scales of the SDQ III measuring general academic and problem-solving self-concept. As expected, self-concept predicts a significant proportion of variance in the confidence factor that is over and above the influence of test scores.     

The effects of fixed‐interval schedules on variability of pigeons' pecking location

Many studies that have investigated performance under reinforcement schedules have measured response rate or interresponse time, which reflect the temporal dimension of responding; however, relatively few studies have examined other dimensions. The present study investigated the effects of fixed‐interval schedules on the location of pigeons' pecking response. A circular response area 22.4 cm in diameter was used so that the pecking responses were effective over a wide range. Pigeons were exposed to a fixed‐interval schedule whose requirement was systematically varied between conditions. Response location moved closer to the location of the last reinforced response as time elapsed in each trial. Additionally, as the fixed‐interval duration requirement increased, response locations shifted to the border of the response area and the variability of response locations increased. These results suggest that fixed‐interval schedules systematically control response location.     

The impact of self‐confidence on the compromise effect

This research reports an investigation into whether the personality aspect of self‐confidence affects the compromise effect. We hypothesize that highly self‐confident people have greater certainty in making decisions and are more attracted to risk‐taking, which makes them less likely to choose the safe or middle option in a large choice set. The three studies involved are conducted using between‐ and within‐subjects experimental designs. Various product categories are used to generalize the findings. Study 1 looks at purchasing decisions and utilizes three scales of self‐confidence, risk preference, and uncertainty; it demonstrates that consumers with high self‐confidence are less likely to choose a compromise option due to high certainty in their decision‐making. Study 2 discovers that people with low self‐confidence are more likely to choose the middle option in a risky condition than in a nonrisky condition. Study 3 decomposes self‐confidence into general and specific self‐confidence, and reveals that people with low general self‐confidence and low specific self‐confidence are more likely to choose the middle option.     

A Monte Carlo evaluation of masked visual analysis in response‐guided versus fixed‐criteria multiple‐baseline designs

We developed masked visual analysis (MVA) as a structured complement to traditional visual analysis. The purpose of the present investigation was to compare the effects of computer‐simulated MVA of a four‐case multiple‐baseline (MB) design in which the phase lengths are determined by an ongoing visual analysis (i.e., response‐guided) versus those in which the phase lengths are established a priori (i.e., fixed criteria). We observed an acceptably low probability (less than .05) of false detection of treatment effects. The probability of correctly detecting a true effect frequently exceeded .80 and was higher when: (a) the masked visual analyst extended phases based on an ongoing visual analysis, (b) the effects were larger, (c) the effects were more immediate and abrupt, and (d) the effects of random and extraneous error factors were simpler. Our findings indicate that MVA is a valuable combined methodological and data‐analysis tool for single‐case intervention researchers.     

On the potential value and limitations of emphasis change and other exploration-enhancing training methods

Two experiments are presented that examine the efficiency of training methods that force trainees to explore the possible strategy space. Both experiments used a 2-dimensional search task. Experiment 1 studies a method that enforces exploration by preventing repetitions within short sequences. It shows that the effect of this "enhanced exploration" method in the abstract setting is similar to the effect of "emphasis change" training (see D. Gopher, 1993) in high cognitive workload tasks. This finding appeared only in strategic spaces where intuitive exploration converges to a local optimum. Experiment 2 compares the effect of exploration enhancement with the effect of guided instruction. The results of the experiments, which are captured well by a generalization of I. Erev and D. A. Gopher's (1999) model of the conditions for the success of emphasis change training, shed light on the limitations and potential of exploration-enhancing training methods.     

Children's preference for mixed‐ versus fixed‐ratio schedules of reinforcement: A translational study of risky choice

Laboratory research has shown that when subjects are given a choice between fixed‐ratio and bi‐valued mixed‐ratio schedules of reinforcement, preference typically emerges for the mixed‐ratio schedule even with a larger ratio requirement. The current study sought to replicate and extend these findings to children's math problem completion. Using an ABCBC reversal design, four fourth‐grade students were given the choice of completing addition problems reinforced on either a fixed‐ratio 5 schedule or one of three mixed‐ratio schedules; an equivalent mixed‐ratio (1, 9) schedule, a mixed‐ratio (1, 11) schedule with a 20% larger ratio requirement, and an equally lean mixed‐ratio (5, 7) schedule without the small fixed‐ratio 1 component. This was followed by a reversal back to the preceding phase in which preference for the mixed‐ratio schedule had been observed, and a final reversal back to the mixed‐ratio (5, 7) phase. Findings were consistent with previous research in that all children preferred the mixed‐ratio (1, 9) schedule over the equivalent fixed‐ratio 5 schedule. Preference persisted for the leaner mixed‐ratio (1, 11) schedule for three of the four children. Indifference or preference for the fixed‐ratio 5 alternative was observed in phases containing the mixed‐ratio (5, 7) schedule. These results extend previous research on risky choice to children's math problem completion and highlight the importance of a small ratio component in the emergence of preference for bi‐valued mixed‐ratio schedules. Implications of these results for arranging reinforcement to increase children's academic responding are discussed.     

Linking extreme response style to response processes: A cross‐cultural mixed methods approach

The aim of this study is to contribute to a better understanding of extreme response style in cross‐cultural research by integrating quantitative and qualitative evidence in a mixed methods design. In the quantitative phase, indexes of extreme response style, derived from quality of life measures from different international studies, were compared between Spain and the Netherlands. Results indicated that extreme responding was more common among Spanish than among Dutch in endorsement of items, but that the opposite was found for frequency scales including never as a response anchor. In the qualitative phase, cognitive interviews were conducted with 25 participants in each country. The integration of quantitative results and qualitative findings suggests that country differences in extreme response style may stem from various sources, including the more independent evaluation of each item by Dutch, the stronger connotations of never for Spanish and stronger emotions triggered by specific topics such as work satisfaction that was more strongly associated with insecurity for Spanish. It is concluded that the integration of quantitative and qualitative evidence can help to understand cross‐cultural similarities and differences in extreme response style.     

Mini‐breaks: the use of escape on a fixed‐time schedule to reduce unauthorized breaks from vocational training sites for individuals with brain injury

This study evaluated mini‐breaks with three individuals who were traumatically brain injured and engaged in unauthorized breaks. The vocational instructors reported that the three participants were having problems staying at their scheduled vocational training sites (walking away without permission). Following baseline, participants were placed on mini‐breaks; that is, participants were given a ten‐minute mini‐break every hour. Thus, mini‐breaks were given without regard to unauthorized breaks. Unauthorized breaks decreased to zero levels for all three participants when mini‐breaks commenced. Following 1 month of the mini‐breaks, two of the participants were put back on a regular break schedule (one 15‐minute AM break and one 15‐minute PM break and a 30‐minute lunch break). The third participant was placed in supported work. The effects of the mini‐breaks were maintained. Copyright © 1999 John Wiley & Sons, Ltd.     

The elimination‐plus lineup: Testing a modified lineup procedure with confidence

The present study examined whether a modified form of a preidentification confidence rating would provide evidence of a suspect's guilt in addition to the identification decision confidence. Participants (N  = 241) viewed a videotaped mock crime and were presented with a target‐present or target‐absent simultaneous, sequential, elimination, or elimination‐plus lineup procedure; both elimination procedures required 2 separate judgments from the witness (i.e., relative and absolute). The elimination‐plus procedure was identical to that of the elimination procedure with the addition of the confidence rating in between judgment 1 and judgment 2. Confidence after judgment 1, confidence after judgment 2, and the average of the 2 confidence ratings with the elimination‐plus procedure significantly predicted accuracy for choosers. Given that confidence has been recognised by the Supreme Court of the United States, these results shed light on a novel way of utilising confidence in the investigative process.     

Eyewitness recall: Regulation of grain size and the role of confidence

Eyewitness testimony plays a critical role in Western legal systems. Three experiments extended M. Goldsmith, A. Koriat, and A. Weinberg-Eliezer's (2002) framework of the regulation of grain size (precision vs. coarseness) of memory reports to eyewitness memory. In 2 experiments, the grain size of responses had a large impact on memory accuracy. Further, participants achieved a compromise between the accuracy and informativeness of their testimony by volunteering precise answers only when likely to be correct. The level of detail reported was strongly, positively related to confidence in the accuracy of the response. This highlights the importance of considering the level of detail, not just the accuracy, of eyewitness testimony.     

Examining the trade‐off between confidence and optimism in future forecasts

Confident business forecasters are seen as more credible and competent (“confidence heuristic”). We explored a boundary condition of this effect by examining how individuals react to the trade‐off between confidence and optimism. Using hypothetical scenarios, we examined this trade‐off from the perspectives of judges (i.e., business owners who hired analysts to make sales predictions) and forecasters (i.e., the analysts hired to make predictions). Participants were assigned to the role of either judges or forecasters and were asked to rate 2 potential forecasts. In the “no trade‐off” condition, the 2 forecasts were aligned in optimism and confidence (the more confident forecast was also more optimistic); in the “trade‐off” condition, the more confident forecast was less optimistic. In Experiment 1, judges were more likely to positively evaluate confident forecasters when confident forecasters were the more (vs. less) optimistic ones. Experiment 2 demonstrated that forecasters were aware of judges' preferences for optimism and strategically relied on methods that resulted in more optimistic (but less reliable) predictions. Experiment 3 directly compared the perspectives of judges and forecasters, revealing that forecasters overestimated judges' preferences for optimism over confidence. The present studies show that forecasters and judges have different views of the trade‐off between confidence and optimism and that forecasters may unnecessarily sacrifice accuracy for optimism.     

A threshold theory account of psychometric functions with response confidence under the balance condition

The study of thresholds for discriminability has been of long‐standing interest in psychophysics. While threshold theories embrace the concept of discrete‐state thresholds, signal detection theory discounts such a concept. In this paper we concern ourselves with the concept of thresholds from the discrete‐state modelling viewpoint. In doing so, we find it necessary to clarify some fundamental issues germane to the psychometric function (PF), which is customarily constructed using psychophysical methods with a binary‐response format. We challenge this response format and argue that response confidence also plays an important role in the construction of PFs, and thus should have some impact on threshold estimation. We motivate the discussion by adopting a three‐state threshold theory for response confidence proposed by Krantz (1969, Psychol. Rev., 76, 308–324), which is a modification of Luce's (1963, Psychol. Rev., 70, 61–79) low‐threshold theory. In particular, we discuss the case in which the practice of averaging over order (or position) is enforced in data collection. Finally, we illustrate the fit of the Luce–Krantz model to data from a line‐discrimination task with response confidence.     

Investigation of the process underpinning vowel‐size correspondence

Vowel‐size correspondence is frequently reported in the literature: Namely, the vowels a and i tend to elicit bigger and smaller images, respectively. Previous studies have speculated that two factors may contribute to this vowel‐size correspondence: the acoustical features of vowels and the speaker's kinesthetic experience of producing them. However, these two factors have been investigated without being considered separately in previous research. In this study, we investigated the process underpinning vowel‐size correspondence by using speeded classification tasks and manipulating the two factors mentioned above separately in two experiments. The results of Experiment 1 indicate that a and i elicited bigger and smaller images even in the absence of kinesthetic experience. The results of Experiment 2 indicate that the proprioception of the size of the oral cavity on its own may not contribute to vowel‐size correspondence. Thus, the acoustic features of vowels mainly contribute to vowel‐size correspondence, although other possibilities are also discussed.     

On the form of ROCs constructed from confidence ratings

A classical question for memory researchers is whether memories vary in an all-or-nothing, discrete manner (e.g., stored vs. not stored, recalled vs. not recalled), or whether they vary along a continuous dimension (e.g., strength, similarity, or familiarity). For yes-no classification tasks, continuous- and discrete-state models predict nonlinear and linear receiver operating characteristics (ROCs), respectively (D. M. Green & J. A. Swets, 1966; N. A. Macmillan & C. D. Creelman, 1991). Recently, several authors have assumed that these predictions are generalizable to confidence ratings tasks (J. Qin, C. L. Raye, M. K. Johnson, & K. J. Mitchell, 2001; S. D. Slotnick, S. A. Klein, C. S. Dodson, & A. P. Shimamura, 2000, and A. P. Yonelinas, 1999). This assumption is shown to be unwarranted by showing that discrete-state ratings models predict both linear and nonlinear ROCs. The critical factor determining the form of the discrete-state ROC is the response strategy adopted by the classifier.