Parallel distributed processing and neuropsychology: A neural network model of Wisconsin card sorting and verbal fluency

Neural networks can be used as a tool in the explanation of neuropsychological data. Using the Hebbian Learning Rule and other such principles as competition and modifiable interlevel feedback, researchers have successfully modeled a widely used neuropsychological test, the Wisconsin Card Sorting Test. One of these models is reviewed here and extended to a qualitative analysis of how verbal fluency might be modeled, which demonstrates the importance of accounting for the attentional components of both tests. Difficulties remain in programming sequential cognitive processes within a parallel distributed processing (PDP) framework and integrating exceedingly complex neuropsychological tests such as Proverbs. PDP neural network methodology offers neuropsychologists co-validation procedures within narrowly defined areas of reliability and validity.     

The design and use of the Bioethics Consultation Form

The emergence of the ethics consultation as a means to resolve moral crises in clinical medicine has revealed the need for a worksheet that would facilitate intake and analysis. The author developed the Bioethics Consultation Form as an attempt to remedy this need. The form is arranged in an outline format and is a useful asset to ethics committee discussions and record keeping. The first section covers basic intake data concerning the patient's medical and personal information, advance directives, and values, as well as the values of the physician and family. After the intake section is completed with the above data, the ethics consultant then turns to the analysis section. This second section allows for (1) the discussion of conflicting values, (2) the identification of priorities, and (3) the elucidation of ethical norms relevant to the case.The Bioethics Consultation Form was adopted by the Patient Care Advisory committee of the Franklin Square Hospital Center in Baltimore, Maryland in 1986. The methodology in the use of the form will be discussed. Further, the potential spectrum of consultative cases that can be analyzed using the form will be highlighted.     

How,in Our Time,Can We Learn about Spirituality?

A rule of thinking which would absolutely prevent me from acknowledging certain kinds of truth, if those kinds of truth were really there, would be an irrational rule.     

Blocking Effects in Two-Choice Discrimination Tasks in Rhesus Monkeys Macaca Mulatta

The Psychological Record - The present experiments investigated blocking effects in rhesus monkeys (Macaca mulatta) in a discrimination learning paradigm using a single stimulus modality. Two...     

Pitch motion with random chord sequences

Perception of global pitch motion was studied through psychoacoustic experiments with random chord sequences. Chords contained either six or eight (fixed) tone elements, being sinusoidal, sawtooth-like, or Shepard tones, which were either on or off according to a probability controlled by the experimenter. Sequences of 2, 4, 5, or 8 chords were used. Identification by subjects of the perceived direction of overall pitch motion (up or down) was found to be well accounted for by a model in which the ultimate pitch motion percept is given by a sum of contributions from selected element transitions--that is, transitions between adjoining tone elements in successive time frames only. In its simplest form, this dipole contribution model has only one free parameter, the perceptual noise for an element transition, which was estimated for various acoustic tone representations and chord arrangements. Results of two experiments, which were carried out independently in two different laboratories, are reported.     

Timed magnitude comparisons of numerical and nonnumerical expressions of uncertainty

Two experiments involving paired comparisons of numerical and nonnumerical expressions of uncertainty are reported. Subjects were timed under two opposing sets of instructions ("choose higher probability" vs. "choose lower probability"). Numerical comparisons were consistently faster and easier than their nonnumerical counterparts. Consistent distance and congruity effects were obtained, illustrating that both numerical and nonnumerical expressions of uncertainty contain subjective magnitude information, and suggesting that similar processes are employed in manipulating and comparing numerical and verbal terms. To account for the general pattern of results obtained, Holyoak's reference point model (1978) was generalized by explicitly including the vagueness of the nonnumerical expressions. This generalized model is based on the notion that probability expressions can be represented by membership functions (Wallsten, Budescu, Rapoport, Zwick, & Forsyth, 1986) from which measures of location for each word, and measures of overlap for each pair can be derived. A good level of fit was obtained for this model at the individual level.