Skill Acquisition and the LISP Tutor

An analysis of student learning with the LISP tutor indicates that while LISP is complex, learning it is simple. The key to factoring out the complexity of LISP is to monitor the learning of the 500 productions in the LISP tutor which describe the programming skill. The learning of these productions follows the power-law learning curve typical of skill acquisition. There is transfer from other programming experience to the extent that this programming experience involves the same productions. Subjects appear to differ only on the general dimensions of how well they acquire the productions and how well they retain the productions. Instructional manipulations such as remediation, content of feedback, and timing of feedback are effective to the extent they give students more practice programming, and explain to students why correct solutions work.     

Impact of situational legitimacy and assertiveness-related anxiety/discomfort on motivation and ability to generate effective criticism responses

This study compares the motivation and the quality of criticism responses of 697 undergraduates who were divided into three levels of situation legitimacy (high, moderate, and low) and two levels (top versus bottom 40 percent) of anxiety related to previous generalized assertiveness behaviours. The impact of gender was also studied. The results showed the legitimacy of the situation for a critical response (preassessed with peer hold-out groups) significantly affected participants' motivation to criticize as well as the quality of their critical responses, notwithstanding the poor quality of all criticism responses. Anxiety related to previous global assertiveness was related to high motivation but not to quality of criticism responses. There were no gender effects. Results are interpreted within an avoidance learning paradigm wherein the connotative meaning of criticism is incongruent with harmonious long-term relationships so that it is suppressed until virtually forced by the specifics of highly legitimate situations.     

Context effects in sentence comprehension: A study of the subjective lexicon

These studies explore the role of context in determining what information about the meanings of words is activated in memory at the time a word is encountered in a sentence. Using a color-naming paradigm, it was shown that both meanings of a word that has two distinct meanings are activated in memory at the time the word is heard in a sentence. This activation occurs even when there is sufficient contextual information to indicate which meaning was intended by the speaker. These results support the hypothesis that there exists in memory an isolable subjective lexicon. They suggest that context which is effective in disambiguating lexical ambiguities in the language has its effect only at a relatively late stage in the cognitive processing involved in language comprehension.     

Rule-based schema matching for ontology-based mediators

Mediating heterogeneous data sources heavily relies on explicit domain knowledge expressed, for example, as ontologies and mapping rules. We discuss the use of logic representations for mapping schema elements onto concepts expressed in a simplified ontology for cultural assets. Starting with a logic representation of the ontology, criteria for a rule-based schema matching are exemplified. Special requirements are the handling of uncertain information and the processing of hierarchical XML structures representing instances.     

Attendance Rates in A Workplace Predict Subsequent Outcome of Employment-Based Reinforcement of Cocaine Abstinence in Methadone Patients

This study assessed whether attendance rates in a workplace predicted subsequent outcome of employment-based reinforcement of cocaine abstinence. Unemployed adults in Baltimore methadone programs who used cocaine (N  =  111) could work in a workplace for 4 hr every weekday and earn $10.00 per hour in vouchers for 26 weeks. During an induction period, participants provided urine samples but could work independent of their urinalysis results. After the induction period, participants had to provide urinalysis evidence of cocaine abstinence to work and maintain maximum pay. A multiple regression analysis showed that induction period attendance was independently associated with urinalysis evidence of cocaine abstinence under the employment-based abstinence reinforcement contingency. Induction period attendance may measure the reinforcing value of employment and could be used to guide the improvement of employment-based abstinence reinforcement.     

Acute episodes of predator exposure in conjunction with chronic social instability as an animal model of post-traumatic stress disorder

People who are exposed to horrific, life-threatening experiences are at risk for developing post-traumatic stress disorder (PTSD). Some of the symptoms of PTSD include persistent anxiety, exaggerated startle, cognitive impairments and increased sensitivity to yohimbine, an alpha(2)-adrenergic receptor antagonist. We have taken into account the conditions known to induce PTSD, as well as factors responsible for long-term maintenance of the disorder, to develop an animal model of PTSD. Adult male Sprague-Dawley rats were administered a total of 31 days of psychosocial stress, composed of acute and chronic components. The acute component was a 1-h stress session (immobilization during cat exposure), which occurred on Days 1 and 11. The chronic component was that on all 31 days the rats were given unstable housing conditions. We found that psychosocially stressed rats had reduced growth rate, reduced thymus weight, increased adrenal gland weight, increased anxiety, an exaggerated startle response, cognitive impairments, greater cardiovascular and corticosterone reactivity to an acute stressor and heightened responsivity to yohimbine. This work demonstrates the effectiveness of acute inescapable episodes of predator exposure administered in conjunction with daily social instability as an animal model of PTSD.