Using New Proximity Measures With Hierarchical Cluster Analysis to Detect Multidimensionality

A new approach for partitioning test items into dimensionally distinct item clusters is introduced. The core of the approach is a new item-pair conditional-covariance-based proximity measure that can be used with hierarchical cluster analysis. An extensive simulation study designed to test the limits of the approach indicates that when approximate simple structure holds, the procedure can correctly partition the test into dimensionally homogeneous item clusters even for very high correlations between the latent dimensions. In particular, the procedure can correctly classify (on average) over 90% of the items for correlations as high as .9. The cooperative role that the procedure can play when used in conjunction with other dimensionality assessment procedures is discussed.     

Generating Random Parallel Test Forms Using CTT in a Computer-Based Environment

This paper describes a procedure for automated test forms assembly based on Classical Test Theory (CTT). The procedure uses stratified random content sampling and test form pre-equating to ensure both content and psychometric equivalence in generating virtually unlimited parallel forms. The procedure extends the usefulness of CTT in automated test form construction, yielding classical item statistics based on representative sample distributions and pre-equated test forms with known psychometric characteristics. A rationale for the procedure is presented followed by an example application and discussion of psychometric considerations related to its use.     

CS modality,context conditioning,and conditioned freezing

Two studies used a one-trial-a-day aversive conditioning procedure with rats as subjects to investigate the effects of a noise versus a light CS on conditioned freezing. Experiment 1 demonstrated that less conditioned freezing was elicited by the light, although the two CSs led to similar levels of freezing to the contextual cues of the conditioning chamber. Experiment 2 replicated these outcomes and showed that the manipulation of CS intensity produced results similar to those of modality, with the more intense CSs eliciting less freezing. The second experiment also determined that freezing to contextual cues resulted from context conditioning. According to the Rescorla-Wagner model, CSs that condition poorly should generate little competition with context conditioning. Since neither the modality nor intensity factor reliably influenced context conditioning, as measured by context-evoked freezing, the studies provide no support for the view that the effects on CS-evoked freezing represent differences in the strength of conditioning to the various stimuli. This finding raises the possibility that all of the CSs conditioned well but varied in their abilities to elicit freezing because they differed in terms of the form of defensive behavior under their control.     

Increase in retention of a taste aversion by weanling rats after a long interval

Weanling rats were tested for retention of an aversion to a novel flavor (chocolate milk) that had been conditioned as a single-element conditioned stimulus (CS) or in compound with a novel ambient odor (banana). The presence of the ambient odor during conditioning had no effect on flavor aversion shortly thereafter, confirming previous results. The flavor aversion observed 21 days after conditioning, however, was significantly stronger for pups conditioned with the single-element CS than for those given the flavor-odor compound as the CS. This retention effect was due to a surprisingincrease in the conditioned aversion observed 21 days after conditioning with the single-element CS. A second experiment confirmed this paradoxical increase in retention of the aversion to chocolate milk. This experiment also verified that no such increase occurred in retention of the conditioned aversion to a different flavor (saccharin), whether the initial aversion was strong or weak. The results may be explained in terms of generalized latent inhibition from consumption of mother’s milk.     

Concept learning by pigeons: Matching-to-sample with trial-unique video picture stimuli

Pigeons were trained to match-to-sample with several new methodologies: a large number of stimuli, computer-drawn color picture stimuli, responses monitored by a computer touch screen, stimuli presented horizontally from the floor, and grain reinforcement delivered onto the picture stimuli. Following acquisition, matching-to-sample concept learning was assessed by transfer to novel stimuli on the first exposure to pairs of novel stimuli. One group (trial-unique), trained with 152 different pictures presented once daily, showed excellent transfer (80% correct). Transfer and baseline performances were equivalent, indicating that the matching-to-sample concept had been learned. A second group (2-stimulus), trained with only two different pictures, showed no evidence of transfer. These results are discussed in terms of the effect of numbers of exemplars on previous failures to find concept learning in pigeons, and the implications of the positive finding from this experiment on abstract concept learning and evolutionary cognitive development.     

Issues in cross-cultural counseling: An examination of the meaning and dimensions of tolerance

While there is a clear need to address the ethical dimensions of cross-cultural counseling, the current literature lacks both a theoretical model of ethnic tolerance and a suitable measure for assessing the construct. The present study addressed this gap in the extant literature by (a) developing a measure of ethnic tolerance based upon extensive field work, (b) examining the measure's reliability and construct validity in light of two models of ethnic tolerance, and (c) examining the relationship of several factors (e.g., age, gender, and exposure to those of a different culture) to scores on the tolerance measure. Results indicated that the tolerance measure was best viewed as a unidimensional construct, had substantial content validity, and had modest construct validity. Respondents with more social contact with immigrants, as well as those who had positive experiences with immigrants, tended to score higher on the tolerance measure. Results underscore both the complexity of factors associated with tolerance and the need for counselor education programs to provide arenas for students to become aware of their own values and biases and how these may affect culturally-different clients.     

Normal versus abnormal genital findings in children: How well do examiners agree?

In order to determine how well medical examiners agree on the significance of certain anogenital findings in children, preselected colposcopic photographs of the anogenital area of 16 patients were shown to 170 medical examiners (82% pediatricians) who were blinded as to the history on each patient. Findings rated most frequently as being suggestive or indicative of penetrating injury included immediate anal dilatation with no stool present (85%), hymenal transection (84%), marked narrowing of the hymenal rim with notching (81%), and a posterior fourchette scar (75%). The agreement between the participants and the experts on the abnormal cases (mean 81%) was significantly higher than on the normal cases (mean 71%, p < .001) and on genital findings (78%) than on anal findings (63%, p = .000). Higher experience level (more cases seen per month) was associated with significantly higher agreement between the participants and the experts on five of eight normal cases and two of four abnormal cases. Use of a colposcope was also associated with higher overall agreement with the experts (74% vs. 44%, p < .0001).