Markov versus quantum dynamic models of belief change during evidence monitoring

Two different dynamic models for belief change during evidence monitoring were evaluated: Markov and quantum. They were empirically tested with an experiment in which participants monitored evidence for an initial period of time, made a probability rating, then monitored more evidence, before making a second rating. The models were qualitatively tested by manipulating the time intervals in a manner that provided a test for interference effects of the first rating on the second. The Markov model predicted no interference, whereas the quantum model predicted interference. More importantly, a quantitative comparison of the two models was also carried out using a generalization criterion method: the parameters were fit to data from one set of time intervals, and then these same parameters were used to predict data from another set of time intervals. The results indicated that some features of both Markov and quantum models are needed to accurately account for the results.

Do patients with schizophrenia exhibit aberrant salience?

BackgroundIt has been suggested that some psychotic symptoms reflect ‘aberrant salience’, related to dysfunctional reward learning. To test this hypothesis we investigated whether patients with schizophrenia showed impaired learning of task-relevant stimulus–reinforcement associations in the presence of distracting task-irrelevant cues.MethodWe tested 20 medicated patients with schizophrenia and 17 controls on a reaction time game, the Salience Attribution Test. In this game, participants made a speeded response to earn money in the presence of conditioned stimuli (CSs). Each CS comprised two visual dimensions, colour and form. Probability of reinforcement varied over one of these dimensions (task-relevant), but not the other (task-irrelevant). Measures of adaptive and aberrant motivational salience were calculated on the basis of latency and subjective reinforcement probability rating differences over the task-relevant and task-irrelevant dimensions respectively.ResultsParticipants rated reinforcement significantly more likely and responded significantly faster on high-probability-reinforced relative to low-probability-reinforced trials, representing adaptive motivational salience. Patients exhibited reduced adaptive salience relative to controls, but the two groups did not differ in terms of aberrant salience. Patients with delusions exhibited significantly greater aberrant salience than those without delusions, and aberrant salience also correlated with negative symptoms. In the controls, aberrant salience correlated significantly with ‘introvertive anhedonia’ schizotypy.ConclusionsThese data support the hypothesis that aberrant salience is related to the presence of delusions in medicated patients with schizophrenia, but are also suggestive of a link with negative symptoms. The relationship between aberrant salience and psychotic symptoms warrants further investigation in unmedicated patients.

TORSION BALANCE STEP ANOMALIES IN NORTHERN TILLMAN COUNTY, OKLAHOMA

The results of a semi‐detailed areal torsion balance survey in Southwestern Oklahoma are shown by means of a gradient‐curvature map, a gravity map, two second derivative contour maps, and gravity and second derivative profiles. Detailed quantitative calculations were made of a number of geological cross sections, two of which are shown in Figs. 8 and 9. Fig. 9 represents the subsurface situation with the highest probability rating, since it combines a high degree of geological probability with the fact that it will reproduce the gravity and second derivative curves of Figs. 6 and 7 very closely. This interpretation embodies a fault with a throw of the order of magnitude of 10,000 feet. If this interpretation is substantially correct, it implies a thick sedimentary section in the down‐thrown block, which might be of great economic interest in prospecting for oil. A comparison of the gravity and second derivative data may be of interest to the geophysicist. The geologist may find the results of this survey interesting because of their possible bearing on the orogeny of the Wichita Mountains.