Psychometric Modeling of response speed and accuracy with mixed and conditional regression

Human performance in cognitive testing and experimental psychology is expressed in terms of response speed and accuracy. Data analysis is often limited to either speed or accuracy, and/or to crude summary measures like mean response time (RT) or the percentage correct responses. This paper proposes the use of mixed regression for the psychometric modeling of response speed and accuracy in testing and experiments. Mixed logistic regression of response accuracy extends logistic item response theory modeling to multidimensional models with covariates and interactions. Mixed linear regression of response time extends mixed ANOVA to unbalanced designs with covariates and heterogeneity of variance. Related to mixed regression is conditional regression, which requires no normality assumption, but is limited to unidimensional models. Mixed and conditional methods are both applied to an experimental study of mental rotation. Univariate and bivariate analyzes show how within-subject correlation between response and RT can be distinguished from between-subject correlation, and how latent traits can be detected, given careful item design or content analysis. It is concluded that both response and RT must be recorded in cognitive testing, and that mixed regression is a versatile method for analyzing test data.I am grateful to Rogier Donders for putting his data at my disposal.     

Speech and non-speech processing in people with specific language impairment: a behavioural and electrophysiological study

McArthur and Bishop (2004) found that people with specific language impairment (SLI) up to 14 years of age have poor behavioural frequency discrimination (FD) thresholds for 25-ms pure tones, while people with SLI upto 20 years of age have abnormal auditory N1--P2--N2 event-related potential (ERP) responses to the same tones. In the present study, we extended these findings to more complex non-speech and speech sounds by comparing younger (around 13 years) and older (around 17 years) teenagers with SLI and controls for their behavioural FD thresholds and N1-P2 ERPs to 25 and 250-ms pure tones, vowels, and non-harmonic complex tones. We found that a subgroup of people with SLI had abnormal responses to tones and vowels at the level of behaviour and the brain, and that poor processing was associated with the spectral complexity of auditory stimuli rather than their phonetic significance. We suggest that both the age of listeners and the sensitivity of psychoacoustic tasks to age-related changes in auditory skills may be crucial factors in studies of sound processing in SLI.     

Care of the Self and Patient Participation in Genetic Discourse: A Foucauldian Reading of the Surgeon General's “My Family Health Portrait” Program

Critics of genetic discourse are concerned that deterministic and discriminatory views of genetics are increasingly becoming adopted. These views argue that current genetic discourse becomes a source of power whereby powerful institutions harm people with so-called “bad” genes. This essay argues that current analyses of the power of genetics discourse are grounded in an improper reading that disempowers patients. Deploying Michel Foucault's concept “care of the self,” this essay claims that genetics discourse is better understood as a way that patients take on power through rhetoric rather than a force that has power over patients. Through a close reading of the “My Family Health Portrait” program, this paper argues that patients experience a process of “subjection” wherein they become agents of and objects of genetics discourse both. This alternative mode of analyzing the power of genetics discourse has implications for our collective understanding of the operations of the care of the self and the uses of genetic information that we propose.     

Do responses of galliform birds vary adaptively with predator size?

Past studies of galliform anti-predator behavior show that they discriminate between aerial and ground predators, producing distinctive, functionally referential vocalizations to each class. Within the category of aerial predators, however, studies using overhead models, video images and observations of natural encounters with birds of prey report little evidence that galliforms discriminate between different raptor species. This pattern suggests that the aerial alarm response may be triggered by general features of objects moving in the air. To test whether these birds are also sensitive to more detailed differences between raptor species, adult chickens with young were presented with variously sized trained raptors (small, intermediate, large) under controlled conditions. In response to the small hawk, there was a decline in anti-predator aggression and in aerial alarm calling as the young grew older and less vulnerable to attack by a hawk of this size. During the same developmental period, responses to the largest hawk, which posed the smallest threat to the young at all stages, did not change; there were intermediate changes at this time in response to the middle-sized hawk. Thus the anti-predator behavior of the adult birds varied in an adaptive fashion, changing as a function of both chick age and risk. We discuss these results in light of current issues concerning the cognitive mechanisms underlying alarm calling behavior in animals.     

Successive reversal of concurrent discriminations by macaques (Macaca mulatta): proactive interference effects

Rhesus monkeys received concurrent within-session training on eight, two-choice object pairs and then underwent successive reversals of these problems. Initially, reversals required about six times more training than acquisition with no improvement over seven successive reversals. Surprisingly, performance on these eight problems was unimpaired if they were embedded in different eight-problem tasks, thereby indicating a release from proactive interference. When the original eight problems again underwent successive reversal, no improvement was seen over seven reversals, although there was significantly less error-per-reversal than in the initial test. Subsequently, monkeys appeared to be developing a learning set for successive reversal because performance on successive reversal of eight novel problems was not different from that seen with the old familiar task. Set acquisition was confirmed when proficient reversal was eventually achieved on both old and new concurrent tasks. Thus, concurrent reversal set did develop, but it required arduous training to overcome proactive interference effects on memory. The ubiquitous influence of measurement context on organization of monkey memory was noted.     

“Hands up Who Wants to Die?”: Primoratz on Responsibility and Civilian Immunity in Wartime

The question of the morality of war is something of an embarrassment to liberal political thinkers. A philosophical tradition which aspires to found its preferred institutions in respect for individual autonomy, contract, and voluntary association, is naturally confronted by a phenomenon that is almost exclusively explained and justified in the language of States, force and territory. But the apparent difficulties involved in providing a convincing account of nature and ethics of war in terms of relations between individuals has not prevented liberal theorists from attempting this task. This paper examines a recent attempt by Igor Primoratz to sketch out the implications of a consistent liberalism for just war doctrine and, in particular, as regards the question of who may be a legitimate target of attack in wartime. Primoratz’s paper itself is a critique of Michael Waltzer’s authoritative exposition of just war theory for failing to be sufficiently and consistently liberal. The debate between these two authors is a productive site for investigating the potential and limitations of liberal theories of just war.     

Enhancing the effects of extinction on attention-maintained behavior through noncontingent delivery of attention or stimuli identified via a competing stimulus assessment

Recent research has shown that the noncontingent delivery of competing stimuli can effectively reduce rates of destructive behavior maintained by social-positive reinforcement, even when the contingency for destructive behavior remains intact. It may be useful, therefore, to have a systematic means for predicting which reinforcers do and do not compete successfully with the reinforcer that is maintaining destructive behavior. In the present study, we conducted a brief competing stimulus assessment in which noncontingent access to a variety of tangible stimuli (one toy per trial) was superimposed on a fixed-ratio 1 schedule of attention for destructive behavior for individuals whose behavior was found to be reinforced by attention during a functional analysis. Tangible stimuli that resulted in the lowest rates of destructive behavior and highest percentages of engagement during the competing stimulus assessment were subsequently used in a noncontingent tangible items plus extinction treatment package and were compared to noncontingent attention plus extinction and extinction alone. Results indicated that both treatments resulted in greater reductions in the target behavior than did extinction alone and suggested that the competing stimulus assessment may be helpful in predicting stimuli that can enhance the effects of extinction when noncontingent attention is unavailable. DESCRIPTORS: Attention-maintained problem behavior, competing stimuli, extinction, functional analysis, noncontingent reinforcement     

Applications of computer-based instruction: using specialized software to aid letter-name and letter-sound recognition

We evaluated computerized training and testing programs with children who were having difficulties learning prereading skills. The programs were derived from equivalence research and were written in authoring software designed for educators. After learning to match uppercase and lowercase printed letters to the corresponding letter names (Tasks 1 and 2), the children matched the letters to one another (Tasks 4 and 5). Then, after learning to match uppercase letters to sounds (Task 3), they also matched lowercase letters to sounds (Task 6) and matched printed to spoken words (Tasks 7 and 8). The results recommend equivalence-based protocols and user-friendly software in further development of prereading instruction.     

Noncontingent reinforcement, alternative reinforcement, and the matching law: a laboratory demonstration

Basic researchers, but not most applied researchers, have assumed that the behavior-decelerating effects of noncontingent reinforcement result at least partly from adventitious reinforcement of competing behaviors. The literature contains only sketchy evidence of these effects because few noncontingent reinforcement studies measure alternative behaviors. A laboratory model is presented in which concurrent schedules of contingent reinforcement were used to establish a "target" and an "alternative" behavior. Imposing noncontingent reinforcement decreased target behavior rates and increased alternative behavior rates, outcomes that were well described by the standard quantitative account of alternative reinforcement, the generalized matching law. These results suggest that adventitious reinforcement of alternative behaviors can occur during noncontingent reinforcement interventions, although the range of conditions under which this occurs remains to be determined in future studies. As an adjunct to applied studies, laboratory models permit easy measurement of alternative behaviors and parametric manipulations needed to answer many research questions.     

Effects of anorectic drugs on food intake under progressive-ratio and free-access conditions in rats

The effects of two anorectic drugs, dexfenfluramine and phentermine, on food intake under different food-access conditions were examined. Experiment 1 compared the effects of these drugs on food intake under a progressive-ratio (PR) schedule and free-access conditions. Dexfenfluramine decreased food intake under both conditions, but the doses required to decrease intake under free-access conditions were higher than those required to reduce intake under the PR condition. Intermediate doses of phentermine sometimes increased breaking points, and higher doses decreased them. Phentermine decreased food intake at the same doses under both access conditions. Thus the potency of dexfenfluramine, but not phentermine, to decrease food-maintained behavior depended upon the food-access condition. Experiment 2 used a novel mixed progressive-ratio schedule of food delivery to study the duration of drug effects. Sessions consisted of five components separated by 3-hr timeouts. The ratio requirement reset at the beginning of each component and a new breaking point was obtained. Both dexfenfluramine and phentermine dose-dependently decreased breaking points early in the session. In some rats, compensatory increases in breaking point were observed. That is, breaking points later in the session increased over control levels, resulting in no change in the total number of food pellets earned for the session compared to control. The present findings suggest that the effects of some anorectic drugs depend upon the access conditions for food; increasing the effort to obtain food may enhance their ability to decrease food-maintained behavior.