Maternal Perceptions of Safeguards for Research Involving Children

Journal of Child and Family Studies - The vitality of clinical research and the health of the public relies on continued efforts to engage children in clinical research in a fully protected and...     

Illusions of Sense in the Tractatus: Wittgenstein and Imaginative Understanding

Certain expositors of the Tractatus have tried to make sense of Wittegnstein's curious revocation of its propositions by suggesting that although they lack content, they nonetheless express ("show," but do not say) some ineffable truths about reality. Such a view Cora Dimaond labels "chickening out." I attempt to diagnose the lingering attraction of the 'chicken' (in this case an attraction to an illusion of sense) by condsidering a (false) parallel with the case of perceptual illusion. To this end, I make a brief excursion into the work of Gareth Evans in order to draw out what the parallel would look like and more specifically how the chicken might be tempted to think that there is indeed such a parallel. In this way, I hope to better 'understand' the chicken and her seduction, and in the process make a plea for not "chickening out." I then turn to a positive consideration of how we should in fact read this work. In particular, I consider Diamond's idea that the Tractatus requires an "imaginative understanding" of its reader, an ability to 'think' oneself into certain philosophical illusions of sense in order to dismantle them from within. I explore exactly what such an imagination involves. In particular, I suggest that it presupposes a kind of 'metaphysical' thesis of its own about the nature of human beings and their innermost tendencies, a position, I argue, that Wittegnstein held.     

Some effects of the conditioned suppression paradigm on operant discrimination performance

Three experiments were conducted with rats to determine the effects of electric shock on responding during an operant discrimination. In two of these experiments, a conditioned suppression procedure was superimposed upon a stimulus signalling the availability of food reinforcement (S(D)). Response rates were greatly suppressed, not only in the warning signal periods which preceded each shock, but in the presence of S(D), and the stimulus signalling the unavailability of reinforcement (S(Delta)) as well. A third experiment, in which a very mild shock was used without a warning signal, demonstrated an increased response rate in S(D) and S(Delta), although this effect was rather unsystematic. In a similar study, Hearst (1965) found an increased rate in S(Delta) independent of any change in the S(D) rate. The present study failed to obtain Hearst's effect but illustrated a suppressive effect with a similar procedure.     

Proof and Canonical Proof

Certain anti-realisms about mathematics are distinguished by their taking proof rather than truth as the central concept in the account of the meaning of mathematical statements. This notion of proof which is meaning determining or canonical must be distinguished from a notion of demonstration as more generally conceived. This paper raises a set of objections to Dummett's characterisation of the notion via the notion of a normalised natural deduction proof. The main complaint is that Dummett's use of normalised natural deduction proofs relies on formalisation playing a role for which it is unfit. Instead I offer an alternative account which does not rely on formalisation and go on to examine the relation of proof to canonical proof, arguing that rather than requiring an explicit characterisation of canonical proofs we need to be more aware of the complexities of that relation.     

Generalization peak shift in rats under conditions of positive reinforcement and avoidance

Rats were trained to discriminate between two click frequencies. One frequency was associated with either variable-interval food reinforcement (Experiment 1) or free-operant avoidance (Experiment 2). The other frequency was associated with the absence of food in Experiment 1 and the absence of shock in Experiment 2. On a click frequency generalization test, the rats in both experiments showed positive peak shift with the shape of the relative gradients being very similar. This is the first reported instance of peak shift in rats when responding was maintained by an avoidance contingency. Nondifferentially trained controls showed that this shift was due exclusively to associative processes, with nonassociative stimulus factors in themselves apparently making no contribution to increased rates at particular stimulus values. These results show the comparability of appetitive and aversive control and support the position that gradient differences do not result from approach versus avoidance per se.