Effects of response disparity on stimulus and reinforcer control in human detection tasks

In two detection experiments, university students reported whether the second of two sequentially presented tones was longer or shorter than the first by responding to stimuli presented on a touch screen. Stimulus disparity and response disparity were manipulated to compare their effects on measures of discrimination and response bias when the reinforcement ratio for correct responses was asymmetric. Choice stimuli consisted of squares filled with different pixel densities. Response disparity was manipulated by varying the difference in density between the two choice stimuli. In both experiments, decreasing stimulus disparity reduced discrimination but had no consistent effect on bias. Decreasing response disparity also reduced discrimination in both experiments, and often reduced estimates of bias. The effects of response disparity on bias were most clear in Experiment 2, in which a greater overall level of response disparity was arranged. The data show that, like corresponding research with pigeons, detection performance of human subjects can be conceptualized as discriminated operants.     

Facilitation of source discrimination in the novelty effect

It has been demonstrated experimentally that recognition of novel items is more accurate than recognition of previously familiarized items. Tulving and Kroll (1995) proposed that this effect is due to novelty detectors in the brain giving processing priority to novel information. Recently, Dobbins et al. (1998) suggested that the effect is due to source discrimination problems. In the present two experiments attempts were made to facilitate source discrimination by having different orienting tasks and materials in the familiarization and in the critical presentations. Degree of familiarization was manipulated by varying number of presentations one, two or three times. The results in Experiment 1 showed that the novelty effect increased linearly as a function of presentations in the familiarization phase. In the second experiment the difference between familiar and novel items was even more pronounced. Enactment at encoding was added as a manipulation during familiarization. The results of Experiment 2 showed that the novelty effect did increase linearly for items with nonenacted encoding (in which the familiarization and the critical phase were more similar) but not for enacted encoding. All subjects reported experiencing source discrimination difficulties in both experiments despite the measures taken to diminish them. It seems safe to conclude that source discrimination difficulties are a part of the novelty effect.     

Ontogeny of early event memory: II. Encoding and retrieval by 2- and 3-month-olds

The ability of 2-month-old infants to discriminate changes in a 5-object crib mobile following a retention interval of 24 hr was assessed using the mobile conjugate reinforcement paradigm. Infants were trained in 3 daily 15-min sessions to produce mobile movement by footkicking. Twenty-four hr later, independent groups received generalization tests with mobiles containing 1–5 novel objects substituted into their original training mobile. A control group was tested with the original training mobile. These findings were compared with findings of 2 previous studies involving identical procedures with 3-month-olds, reanalyzed for measures of individual performance over successive test minutes. Although, in absolute terms, 2-month-olds had a flat generalization gradient relative to 3-month-olds, when each infant's kick rate during the generalization test was expressed relative to that infant's kick rate before, and at the end of, training, it was found that the generalization gradients of 2- and 3-month-olds were indistinguishable. The relative response measures indicated a surprising degree of specificity by both age groups: Test mobiles containing more than 1 novel object did not cue retrieval, but test mobiles containing no more than 1 new object yielded perfect retention and complete generalization. These data indicate that infants as young as 2 months are capable of encoding and maintaining a representation of the specific details of their training context for at least 24 hr and, after that delay, can perform fine discriminations based on the discrepancy between their test context and that representation.     

Social Identity, System Justification, and Social Dominance: Commentary on Reicher, Jost et al., and Sidanius et al.

The articles by Reicher (2004 ), Jost, Banaji, and Nosek (2004 ), and Sidanius, Pratto, van Laar, and Levin (2004 ) discuss the strengths and weaknesses of social identity theory ( Tajfel & Turner, 1979 ), system justification theory ( Jost & Banaji, 1994 ), and social dominance theory ( Sidanius, 1993 ). The latter two theories grew out of a critique of social identity theory, but this critique relates more to deficiencies in social identity research than to deficiencies in the theory itself. More balanced and comprehensive social identity research is required in order to allow a fair assessment of the theory's limitations. In addition, Reicher (2004 ) and Huddy (2004 ) are correct that only social identity theory offers the potential for explaining social change and social stability.     

Psychosocial Correlates of Medical Mistrust Among African American Men

The current study proposed and tested a conceptual model of medical mistrust in a sample of African American men (N = 216) recruited primarily from barbershops in the Midwest and Southeast regions of the United States. Potential psychosocial correlates were grouped into background factors, masculine role identity/socialization factors, recent healthcare experiences, recent socioenvironmental experiences (e.g., discrimination), and healthcare system outcome expectations (e.g., perceived racism in healthcare). Direct and mediated relationships were assessed. Results from the hierarchical regression analyses suggest that perceived racism in healthcare was the most powerful correlate of medical mistrust even after controlling for other factors. Direct effects were found for age, masculine role identity, recent patient–physician interaction quality, and discrimination experiences. Also, perceived racism in healthcare mediated the relationship between discrimination experiences and medical mistrust. These findings suggest that African American men’s mistrust of healthcare organizations is related to personal characteristics, previous negative social/healthcare experiences, and expectations of disparate treatment on the basis of race. These findings also imply that aspects of masculine role identity shape the tone of patient–physician interactions in ways that impede trust building processes.     

Titrating-delay matching-to-sample in the pigeon

The titrating-delay matching-to-sample (TDMTS) procedure offers researchers an additional behavioral task thought to capture some important features of remembering. In this procedure, the delay between sample offset and comparison onset adjusts as a function of the subject's performance. Specifically, correct matches increase the delay and incorrect matches decrease the delay, and steady-state titrated delays serve as the primary dependent measure. The present series of experiments investigated the effects of several procedural variables on performance in TDMTS procedures in an effort to elucidate better its features to allow for more precision in future use. Experiment 1 reports results from a parametric analysis of fixed-ratio response requirements on the sample key that indicated improved remembering in the form of higher daily titrated delay values as the requirement was increased. Experiment 2 investigated the extent to which the initial delay value in each session affected session-wide delay values. Results indicated that regardless of value of the initial delay, the subjects' performances adjusted the delay values in the direction of the known baseline delay-value levels. Experiment 3 manipulated the step size by which delay values were adjusted and the results indicated that larger step sizes increased both session-to-session variability and within-session range of titrated delay values, although the average values remained approximately the same. These results suggest that the TDMTS task serves as a promising procedure to study what many refer to as memory.     

Establishing initial auditory‐visual conditional discriminations and emergence of initial tacts in young children with autism spectrum disorder

Children with autism spectrum disorder (ASD) often display impaired listener skills, and few studies have evaluated procedures for establishing initial auditory‐visual conditional discrimination skills. We developed and evaluated a treatment package for training initial auditory‐visual conditional discriminations based on the extant research on training such discriminations in children with ASD with at least some preexisting skills in this area. The treatment package included (a) conditional‐only training, (b) prompting the participant to echo the sample stimulus as a differential observing response, (c) prompting correct selection responses using an identity‐match prompt, (d) using progressively delayed prompts, and (e) repeating trials until the participant emitted an independent correct response. Results indicated all participants mastered all listener targets, and the two participants for whom we tested the emergence of corresponding tacts showed mastery of most tacts without direct training. We discuss these results relative to prior research on listener skills and tacts.     

A comparison of blocked and mixed‐trial methods for teaching auditory–visual discriminations

Behavior analysts typically teach conditional discriminations in a mixed‐trial format but may switch to a blocked‐trial format for learners displaying limited acquisition. No known research has shown that mixed‐trial methods are more effective or efficient than blocked‐trial methods for teaching discriminations, so it is not clear why this format has been adopted as the “first‐line” intervention. We compared blocked and mixed‐trial formats for teaching novel auditory–visual discriminations to three adults with intellectual and developmental disabilities (IDD). Results show blocked‐trial methods resulted in faster skill acquisition in all cases, suggesting this format may be a preferable starting point for instruction.     

A review of error correction procedures during instruction for children with developmental disabilities

Error correction procedures are remedial strategies presented following an incorrect response that increases the probability that a correct response will occur in the future. Error correction is commonly used during skill acquisition programs for children with developmental disabilities; however, the specific strategy used may differ considerably. Recent comparative studies have examined the effect of numerous error correction procedures on the efficiency of acquisition for children with developmental disabilities. Despite considerable merit, minor procedural differences and unique terms for similar procedures likely affect comparisons across studies. Here, we clarify the procedures and findings of these studies and suggest areas of future research.     

Multiracial Identity,Color‐Blind Racial Ideology,and Discrimination: Professional Counseling Implications

Because of the expansive multiracial population growth in the United States, the authors explored multiracial identity integration (MII), color‐blind racial ideology (CBRI), and discrimination using regression analyses with 288 individuals. CBRI and discrimination significantly correlated and predicted MII, with 15.3% of the variance explained by discrimination and CBRI. Moderation analysis revealed that CBRI did not moderate the relationship between discrimination and MII. Continued research among multiracial individuals is recommended to better understand the CBRI and racial identity link.