Multiphasic neuronal transfer functions for representing temporal structure

Neural network models of timing have struggled to account for animal timing capabilities using the accepted connectionist assumptions, in most cases without postulating the existence of explicit neuronal time-keeping mechanisms. Current ethological and physiological data, however, suggest that cellular oscillators form the foundation for animals’ temporal capacities. We propose that these oscillators could be used as temporal filters that capture the temporal structure of the animal’s experience. A model is presented that accounts for a number of the salient features of the feeding anticipatory response with only a single circadian filter. This model goes beyond current entrainment models in that it correctly predicts the relationship between the feeding period and the anticipatory interval. An alternative approach using multiple filters is examined that can account for animals’ ability to correctly anticipate two daily feeding times.     

Structured propostions and sentence structure

It is argued that taken together, two widely held claims ((i) sentences express structured propositions whose structures are functions of the structures of sentences expressing them; and (ii) senteces have underlying structures that are the input to semantic interpretation) suggest a simple, plausible theory of propositional structure. According to this theory, the structures of propositions are the same as the structures of the syntactic inputs to semantics they are expressed by. The theory is defended against a variety of objections.I have benefitted from discussions with Michael Jubien, Michacl Liston, Paul Teller, Howard Wettstein, Mark Wilson and especially David Copp. The comments of Mark Richard and an anonymous referee for Journal of Philosophical Logic on an earlier draft resulted in a much improved paper. Various circumstances resulted in this paper appearing after King [1995], though the latter was written later and amends the present view in several ways. See notes 9, 13, 15 and 33 of King [1995].     

Is the human mind a Turing machine?

In this paper I discuss the topics of mechanism and algorithmicity. I emphasise that a characterisation of algorithmicity such as the Turing machine is iterative; and I argue that if the human mind can solve problems that no Turing machine can, the mind must depend on some non-iterative principle — in fact, Cantor's second principle of generation, a principle of the actual infinite rather than the potential infinite of Turing machines. But as there has been theorisation that all physical systems can be represented by Turing machines, I investigate claims that seem to contradict this: specifically, claims that there are noncomputable phenomena. One conclusion I reach is that if it is believed that the human mind is more than a Turing machine, a belief in a kind of Cartesian dualist gulf between the mental and the physical is concomitant.     

A dotted line assimilates in visibility to a solid line

This study tested the theory that a context-produced increase in visibility of a target is due to its assimilation in visibility to the context. A context+target and a context are discriminated better than are a target and background. This occurs for two different context+targets in which the context is a solid line and the target is a dotted line. But it does not occur when solid lines replace these dotted lines. The dotted lines are much less visible than the solid lines. Therefore, the dotted lines increase in similarity in visibility to the solid lines, which is assimilation, but for visibility, rather than for a typical part. Assimilation does not occur between perceptually equal parts. Consequently, the reason why the two context+targets with only solid lines do not result in increases in visibility may be that these lines are sufficiently equal in visibility that assimilation in visibility is precluded. So, the theory is supported. This theory is consistent with evidence that one group (phenomenal whole) is associated with both assimilation and an increase in visibility. Accordingly, a stimulus with a relatively large distance between its solid and dotted lines is apprehended as a relatively weak group, and does not result in an increase in visibility.     

The social phobia and anxiety inventory: Further validation in two nonclinical samples

The Social Phobia and Anxiety Inventory (SPAI) has been developed to assess specific symptoms of social phobia and agoraphobia. Although the SPAI was developed with both clinical and nonclinical populations, research with this measure is currently focused primarily on clinical samples. We examined the factor structure and psychometric properties of the SPAI in adult community and college undergraduate samples. We found that single-sample and multisample confirmatory factor analyses provided support for extending use of the correlated two-factor SPAI subscales to our nonclinical samples. In addition, we found evidence for the internal consistency reliability of the SPAI subscales in both samples. Limitations and suggestions for future research are discussed.     

What Is a Philosophical Analysis?

Philosophical Studies -     

The role of R-S1 expectancy in discrimination and discrimination reversal learning

Four experiments assessed the role of response-reinforcement (R-S¹) expectancy as rats either learned a discrimination or a discrimination reversal. Experiment 1 showed that the higher the percentage of reinforcement during nondiscriminative pretraining the more quickly a subsequent discrimination is learned. Experiment 2 demonstrated that the overlearning reversal effect (ORE) can be obtained even though the overtraining phase consists of responses to a single neutral card. In Experiment 3 subjects were again overtrained on a single neutral stimulus under conditions of varying reinforcement. ORE was apparent under reinforcement of a high percentage of responses but was not apparent under reinforcement of a low percentage. Experiment 4 revealed that the fewer errors a subject makes prior to reversal the better its reversal performance is. Results of these studies were discussed in terms of generalized attention theories and the expectancy notions of Bolles (Psychological Review, 1972, 79(5), 394–409.     

Constant-force cable coupler and activity monitor for small unrestrained animals

A mercury commutator with retracting cable coupler and activity monitor is described. A coiled spring maintains stable tension on a spool that takes up slack in a flexible cable attached to the electrode skull cap of a freely moving rat. This vertical movement-compensation assembly swivels on a low-friction horizontal bearing that follows the animal’s circular movements. A sensitive measure of activity is achieved by using a photobeam to detect movement of the cable spool when the animal moves its head. The apparatus can be used with low-ceiling chambers and is suited to long-term continuous recording and stimulation experiments.