A conceptual and psychometric framework for distinguishing categories and dimensions

An important, sometimes controversial feature of all psychological phenomena is whether they are categorical or dimensional. A conceptual and psychometric framework is described for distinguishing whether the latent structure behind manifest categories (e.g., psychiatric diagnoses, attitude groups, or stages of development) is category-like or dimension-like. Being dimension-like requires (a) within-category heterogeneity and (b) between-category quantitative differences. Being category-like requires (a) within-category homogeneity and (b) between-category qualitative differences. The relation between this classification and abrupt versus smooth differences is discussed. Hybrid structures are possible. Being category-like is itself a matter of degree; the authors offer a formalized framework to determine this degree. Empirical applications to personality disorders, attitudes toward capital punishment, and stages of cognitive development illustrate the approach.     

Mother Teresa versus Ebenezer Scrooge: mortality salience leads proselfs to endorse self-transcendent values (unless proselfs are reassured)

Recently, Jonas, Schimel, Greenberg, and Pyszczynski demonstrated that mortality salience (MS) increased contributions to (an ingroup) charity (i.e., the Scrooge effect). The authors examined whether individual differences in social value orientations would moderate the Scrooge effect. In line with an Ebenezer shift hypothesis, proselfs were less likely than prosocials to endorse self-transcendent values in a dental pain control condition but were indistinguishable from prosocials in an MS condition as proselfs increased endorsement of self-transcendent values under MS (Experiments 1 and 2a). However, when participants gave their impressions of an unfavorable prosocial or a favorable proself prior to the MS manipulation, proselfs were again less likely than prosocials to endorse self-transcendent values (Experiments 2a and 2b), suggesting that proselfs are unlikely to transform into prosocials under conditions of MS when given reasons to disidentify with prosocial values or identify with proself values.     

Compatibility effects based on stimulus and response numerosity

Four choice reaction time experiments documented a stimulus-response (S-R) compatibility effect involving the numbers of stimuli and responses. In Experiment 1, the stimulus consisted of one or two tones, and the correct response was either one or two taps of a response key. Responses were much faster with a compatible S-R assignment, in which the number of taps matched the number of tones, than with an incompatible assignment in which these numbers mismatched. Experiments 2 and 3 replicated this effect, using visual stimuli and bimodal stimuli, respectively, suggesting that auditory/manual rhythmic compatibility is not essential to it. Experiment 4 showed that an analogous but smaller effect is obtained when stimuli are the digits 1 and 2. This new numerosity-based compatibility effect has general theoretical implications regarding the mechanisms responsible for compatibility effects and practical implications for interface design.     

The role of metabotropic glutamate receptors and cortical adaptation in habituation of odor-guided behavior

Decreases in behavioral investigation of novel stimuli over time may be mediated by a variety of factors including changes in attention, internal state, and motivation. Sensory cortical adaptation, a decrease in sensory cortical responsiveness over prolonged stimulation, may also play a role. In olfaction, metabotropic glutamate receptors on cortical afferent pre-synaptic terminals have been shown to underlie both cortical sensory adaptation and habituation of odor-evoked reflexes. The present experiment examined whether blockade of sensory cortical adaptation through bilateral infusion of the group III metabotropic glutamate receptor antagonist cyclopropyl-4-phosphonophenylglycine (CPPG) into the anterior piriform cortex could reduce habituation of a more complex odor-driven behavior such as investigation of a scented object or a conspecific. The results demonstrate that time spent investigating a scented jar, or a conspecific, decreases over the course of a continuous 10 minute trial. Acute infusion of CPPG bilaterally into the anterior piriform cortex significantly enhanced the time spent investigating the scented jar compared to investigation time in control rats, without affecting overall behavioral activity levels. Infusions into the brain outside of the piriform cortex were without effect. CPPG infusion into the piriform cortex also produced an enhancement of time spent investigating a conspecific, although this effect was not significant.     

Implementation of a comprehensive schoolwide behavioral intervention: The ABC program

The Academic and Behavioral Competencies (ABC) Program, a schoolwide program to reduce classroom disruption and encourage rule following, academic task completion, and homework completion, is described. The program was initially developed and implemented in an elementary school with a high-risk population. Data from teachers, parents, and children indicate high levels of satisfaction with the program. In addition, unobtrusive measures of program impact, reported as reductions in referrals to the principal's office, suspensions, and increases in homework completion rates relative to the year prior to implementation of the program, suggest a preliminary positive impact of the program. A replication is reported for another school district, with teacher evaluations of satisfaction and effectiveness reported, supporting the flexibility and adaptability of the program. Although the present article does not constitute a systematic evaluation of the ABC Program, it presents preliminary data on the process of implementation and stakeholder satisfaction.     

Children's perceptions of dangerous substances

The aim of this research was to examine age differences in children's perceptions of dangerous substances. Children's responses to photographs of child models encountering alcohol, a syringe, medicine, glue, and household bleach were coded for recognition of substance, awareness of potential danger, and understanding of danger or harm. Responses from 59 children (28 girls and 31 boys, who were all children of the required age in an urban primary school) were compared across three age groups (6-7 years, 8-9 years, and 10-11 years). 15 to 18 of 20 children in each of three age groups recognised all the dangerous substances. Significant differences across age groups were found for awareness of the potential harm from alcohol, glue, and medicine, but not for the syringe or bleach. Children reported less serious consequences from ingesting alcohol than other substances, the consequences of sniffing glue tended to be confused with the sticking properties of glue, children's understanding of transmission of germs, disease, and AIDS through syringes was varied, and there was a tendency among the older children to underestimate the potential harm of self-administration of medicines. Findings were discussed in relation to children's concepts of danger and safety education.     

Threshold estimation in two-alternative forced-choice (2AFC) tasks: the Spearman-Kärber method

The Spearman-K?rber method can be used to estimate the threshold value or difference limen in two-alternative forced-choice tasks. This method yields a simple estimator for the difference limen and its standard error, so that both can be calculated with a pocket calculator. In contrast to previous estimators, the present approach does not require any assumptions about the shape of the true underlying psychometric function. The performance of this new nonparametric estimator is compared with the standard technique of probit analysis. The Spearman-K?rber method appears to be a valuable addition to the toolbox of psychophysical methods, because it is most accurate for estimating the mean (i.e., absolute and difference thresholds) and dispersion of the psychometric function, although it is not optimal for estimating percentile-based parameters of this function.     

Effects of redundant visual stimuli on temporal order judgments

Four experiments were conducted in order to compare the effects of stimulus redundancy on temporal order judgments (TOJs) and reaction times (RTs). In Experiments 1 and 2, participants were presented in each trial with a tone and either a single visual stimulus or two redundant visual stimuli. They were asked to judge whether the tone or the visual display was presented first. Judgments of the relative onset times of the visual and the auditory stimuli were virtually unaffected by the presentation of redundant, rather than single, visual stimuli. Experiments 3 and 4 used simple RT tasks with the same stimuli, and responses were much faster to redundant than to single visual stimuli. It appears that the traditional speedup of RT associated with redundant visual stimuli arises after the stimulus detection processes to which TOJs are sensitive.