Interacting plans

The paper explores certain phenomena which arise in stories, conversations, and human activity in general when the plans of two individuals are formed and carried out in an interactive situation. A notation system for representing interacting plans is introduced and applied in the analysis of a small portion of “Hansel and Gretel.” The analysis illustrates how a single actor plan can be modified by the needs of cooperative interaction with others and how cooperative interactive episodes can be transformed and used deceptively by one party in achieving his or her own covert goals.     

P50 sensory gating deficits in schizotypy

Sensory gating is the ability to filter out irrelevant stimuli from the environment. Individuals with schizophrenia consistently demonstrate deficits in this ability leading to sensory overload and cognitive fragmentation. This dysfunction has also been found in schizotypy, which is defined as a manifestation of nonclinical symptoms qualitatively similar to those found in schizophrenia. In the present study, auditory sensory gating was assessed in healthy individuals by testing the attenuation of the P50 event-related potential. The degree of suppression was then correlated with schizotypy by using the O-LIFE questionnaire. Relative to the low-scoring individuals, P50 suppression was significantly reduced in those with high levels of schizotypy. Furthermore, the degree of deficit in P50 gating correlated with both cognitive disorganisation and impulsive nonconformity dimensions of schizotypy. These results suggest that schizotypal individuals may have early sensory gating deficits similar to schizophrenia patients, especially if they display a disorganised or impulsive profile. As they do not exhibit overt psychotic symptoms, it is likely that such deficits represent an underlying core cognitive dysfunction within the schizophrenia spectrum.     

Diagnostic models for procedural bugs in basic mathematical skills

A new diagnostic modeling system for automatically synthesizing a deep-structure model of a student's misconceptions or bugs in his basic mathematical skills provides a mechanism for explaining why a student is making a mistake as opposed to simply identifying the mistake. This report is divided into four sections: The first provides examples of the problems that must be handled by a diagnostic model. It then introduces procedural networks as a general framework for representing the knowledge underlying a skill. The challenge in designing this representation is to find one that facilitates the discovery of misconceptions or bugs existing in a particular student's encoding of this knowledge. The second section discusses some of the pedagogical issues that have emerged from the use of diagnostic models within an instructional system. This discussion is framed in the context of a computer-based tutoring/gaming system developed to teach students and student teachers how to diagnose bugs strategically as well as how to provide a better understanding of the underlying structure of arithmetic skills. The third section describes our uses of an executable network as a tool for automatically diagnosing student behavior, for automatically generating “diagnostic” tests, and for judging the diagnostic quality of a given exam. Included in this section is a discussion of the success of this system in diagnosing 1300 school students from a data base of 20.000 test items. The last section discusses future research directions.