Stimulus conditions affecting rate of acquisition in a computer-operated version of the two-way active avoidance procedure

Several experiments were performed with rats in order to investigate the stimulus conditions affecting the rate of acquisition of two-way active avoidance. The number of trials per session, the duration of the Conditioned Stimulus (CS), the intertrial interval (pause time), and the intensity of the shock presentation were each varied in separate experiments. The optimal, yet practicable, conditions required to obtain a fast rate of acquisition included 40 to 60 trials per session, a 40-sec intertrial interval, a 10-sec Conditioned Stimulus presentation and a shock intensity of 1.0 mA. These results are discussed with regard to the problem of standardization in behavioral research manipulating biological independent variables.     

KAUFMAN'S RESPONSE TO LUCRETIUS

Abstract: The symmetry argument is an objection to the ‘deprivation approach’– the account of badness favored by nearly all philosophers who take death to be bad for the one who dies. Frederik Kaufman's recent response to the symmetry argument is a development of Thomas Nagel's suggestion that we could not have come into existence substantially earlier than we in fact did. In this paper, I aim to show that Kaufman's suggestion fails. I also consider several possible modifications of his theory, and argue that they are unsuccessful as well.     

SMOKING AND NIGHT DRIVING

Two experiments were performed with an apparatus simulating night driving conditions in order to study the effect of smoking on detection time and redetection time after glare. In the experimental sessions the subjects smoked two standard cigarettes during 15 min. There were no significant differences in results between these sessions and the control sessions without smoking. The conclusion is that the effect of tobacco smoking on the ability to detect objects on the road is from a practical point of view negligible.     

Encoding strategy and retroactive interference in short-term memory

Abstract.— The effect of encoding strategy upon retroactive interference in STM was studied. The subjects were presented two trigrams for retention with the Brown-Peterson method. In half the cases they were to recall both trigrams, in half to recall only the first. The results showed higher recall with the associative than with the rehearsal strategy. An increase in level of retroactive interference was found to increase number of retroactive interference errors in the rehearsal strategy condition and number of omissions in the associative strategy condition. The results were interpreted in terms of the memory trace integration hypothesis.     

Recall as a function of orienting task and retrieval cue

Abstract.— In an incidental learning experiment, a 40 word list with 4 words representing each of 10 taxonom-ic categories and beginning with each of 10 first letters was presented to 120 subjects. Half the subjects sorted the words according to category, half according to initial letter. After an interval of either 1 or 6 min, retention was measured with cued or free recall tests. The subjects in the Category sort-Category cue condition obtained higher recall than the subjects in the Category sort-Letter cue condition, whereas level of recall did not differ between the Letter sort-Letter cue and Letter sort-Category cue conditions. These results together with other results from the experiment were considered as arguments against the Encoding Specificity Principle but in favor of a theory separating encoding from retrieval.     

Catecholamine output in school children as related to performance and adjustment

Johansson, G. Frankenhaeuser, M. & Magnusson, D. Catecholamine output in school children as related to performance and adjustment. Scand. J. Psychol., 1973, 14, 20–28.-Excretion of two catecholamines, adrenaline and noradrenaline, was studied in a group of 240 children, sampled from a longitudinal study, during a "passive" period (viewing a film) and a subsequent "active" period (performing an arithmetic test). In the group of boys the mean adrenaline excretion increased significantly during the active as compared with the passive period. Among the children of both sexes, those who increased their adrenaline output during the arithmetic test as compared with the preceding passive period, performed better on the test in terms of speed and endurance, than did children who did not respond to mental work by adrenaline increase. Significant positive correlations were found between the secretion of both catecholamines and teachers' ratings indicating good social adjustment and emotional stability, as well as with measures of the pupils' subjective satisfaction with their school environment.     

Serotonin neurons and aversive conditioning in the rat

The acute and long-term effects of p -chloroamphetamine (PCA) on one-way and two-way active avoidance (AA), passive avoidance (PA) learning, fear retention (FR) and on central monoamine concentrations were examined in the male rat. Acute PCA administration (0.63–5 mg/kg i.p.), which releases presynaptic 5-HT, produced a dose-related impairment of both one-and two-way AA acquisition, AA retention, PA and fear retention. The selective serotonin (5-HT) uptake inhibitor zimelidine, but not the noradrenaline (NA) uptake inhibitor desipramine, blocked the avoidance deficit induced by acute PCA. Degeneration of brain 5-HT neurons by a high neurotoxic dose of PCA (2 × 10 mg/kg i.p.) failed to change AA and PA learning but blocked the avoidance deficit induced by acute PCA. Degeneration of locus coeruleus NA neurones with DSP4 (1 × 50 mg/kg), a selective NA neurotoxin, failed to block the acute PCA action. Thus, the acute avoidance learning impairment appears to be specifically related to the acute release of endogenous 5-HT. Both acute and long-term PCA treatment affected 5-HT neurones preferentially in the forebrain while marginal effects were observed in the midbrain and spinal cord. A marked impairment in the retention and retrieval of fear conditioning in the rat was also observed following acute PCA administration. The serotoninergic mechanisms underlying the retrieval deficit were found to be similar but not identical to those involved in AA acquisition. These results suggest an important role for central 5-HT neurones in aversive learning processes. The possible involvement of 5-HT neurones in learning, memorial and/or retrieval processes is discussed.     

Serotonin neurons and aversive conditioning in the rat

The acute and long-term effects of p-chloroamphetamine (PCA) on one-way and two-way active avoidance (AA), passive avoidance (PA) learning, fear retention (FR) and on central monoamine concentrations were examined in the male rat. Acute PCA administration (0.63–5 mg/kg i.p.), which releases presynaptic 5-HT, produced a dose-related impairment of both one-and two-way AA acquisition, AA retention, PA and fear retention. The selective serotonin (5-HT) uptake inhibitor zimelidine, but not the noradrenaline (NA) uptake inhibitor desipramine, blocked the avoidance deficit induced by acute PCA. Degeneration of brain 5-HT neurons by a high neurotoxic dose of PCA (2 × 10 mg/kg i.p.) failed to change AA and PA learning but blocked the avoidance deficit induced by acute PCA. Degeneration of locus coeruleus NA neurones with DSP4 (1 × 50 mg/kg), a selective NA neurotoxin, failed to block the acute PCA action. Thus, the acute avoidance learning impairment appears to be specifically related to the acute release of endogenous 5-HT. Both acute and long-term PCA treatment affected 5-HT neurones preferentially in the forebrain while marginal effects were observed in the midbrain and spinal cord. A marked impairment in the retention and retrieval of fear conditioning in the rat was also observed following acute PCA administration. The serotoninergic mechanisms underlying the retrieval deficit were found to be similar but not identical to those involved in AA acquisition. These results suggest an important role for central 5-HT neurones in aversive learning processes. The possible involvement of 5-HT neurones in learning, memorial and/or retrieval processes is discussed.