Nonintervention into siblings' fighting as a catalyst for learned helplessness

The hypothesis that siblings fight simply to attract adults' attention has enjoyed much speculation and some study of children's fighting in recent years. Current research indicates that refusing to intervene causes fighting to wane, supposedly because children will adequately solve problems by themselves if left to do so. The phenomenon of learned helplessness, in which lethargy and despair result from an inability to escape pain, has been applied to battered spouses. This work tests the hypothesis that nonintervention into siblings' fighting is more likely to allow one child to establish superiority over another and that fighting stops because the defeated learns helplessness in the manner of an abused spouse. Implications and alternative methods of dealing with fighting are explored.     

The harmonic bandwidth of phase-reversal discrimination

Previous studies have shown that 180° relative phase shifts inf + 2f gratings are discriminated when the cosine or the sine component of the shift exceeds some-criterion (Bennett & Banks, 1987; Field & Nachmias, 1984). The current experiments demonstrate that this result holds-for other two-component gratings, provided that the components are within two to three octaves of each other. For frequency differences greater than two to three octaves, phase-reversal discrimination is impossible. A simple model that discriminates phase shifts on the basis of changes in the responses of even- and odd-symmetric spatial filters can account for the results.     

Perceptual learning in flavour aversion conditioning

In each of four experiments, rats drank a solution of saline or of lemon and saline shortly before receiving an injection of lithium chloride, and the generalization of the resulting aversion to sucrose or to lemon and sucrose was measured. There was little generalization from saline alone to sucrose alone, and prior exposure to the two solutions had no effect on their discriminability. An aversion conditioned to lemon-saline, however, did generalize to lemon-sucrose, and the extent of this generalization was substantially reduced by prior exposure to the two compound solutions. This perceptual learning effect was partly, but not entirely, attributable to the latent inhibition of the common element, lemon, produced by exposure to the two compounds: animals pre-exposed to lemon alone discriminated between lemon-saline and lemon-sucrose better than animals pre-exposed to saline and sucrose alone; but exposure to the three elements in isolation was not as effective as exposure to the two compound solutions in enhancing their discriminability. The final experiment established that one critical feature of compound pre-exposure is that it involves experience of saline and sucrose in the presence of the same common element. According to an associative theory of perceptual learning, this would result in the establishment of inhibitory associations between saline and sucrose, thus reducing generalization between the two compound solutions.     

Post-extinction conditional stimulus valence predicts reinstatement fear: Relevance for long-term outcomes of exposure therapy

Exposure therapy for anxiety disorders is translated from fear conditioning and extinction. While exposure therapy is effective in treating anxiety, fear sometimes returns after exposure. One pathway for return of fear is reinstatement: unsignaled unconditional stimuli following completion of extinction. The present study investigated the extent to which valence of the conditional stimulus (CS+) after extinction predicts return of CS+ fear after reinstatement. Participants (N = 84) engaged in a differential fear conditioning paradigm and were randomised to reinstatement or non-reinstatement. We hypothesised that more negative post-extinction CS+ valence would predict higher CS+ fear after reinstatement relative to non-reinstatement and relative to extinction retest. Results supported the hypotheses and suggest that strategies designed to decrease negative valence of the CS+ may reduce the return of fear via reinstatement following exposure therapy.