Attention, memory, and cigarette smoking.

Four experiments tested the effects of smoking one cigarette on verbal memory and attention. In Experiment I, 18 men were tested under three conditions in a repeated-measures design (pretrial smoking, posttrial smoking, no smoking). Recall of a 50-word list was tested immediately and after intervals of 10 and 45 min. Pretrial smoking resulted in improved recall 10 and 45 min after learning, but not immediately. Posttrial smoking was ineffectual. In Experiment II, three posttrial smoking intervals (1, 5, and 30 min after presentation of a 20-word list) were compared with pretrial smoking and no smoking using a between-subjects design. The 76 light, moderate, and heavy smokers in Experiment II smoked a 1.38 mg nicotine cigarette and were tested 24 h later. Improved recall occurred for pretrial smoking, but not for any posttrial smoking interval and for light and moderate smokers only. Experiment III compared a low (0.40 mg) and high (1.38 mg) level of nicotine cigarette in light and heavy smokers using pretrial smoking. The high-nicotine cigarette resulted in improved recall for both immediate- and delayed-recall tests. The low-nicotine cigarette was less effective. Light and heavy smokers differed in effect of smoking on heart rate, but not in effect of smoking on recall. Experiment IV found no effect of smoking on depth of processing. The possible mechanisms by which nicotine affects recall are discussed.

Effects of alcohol, congeners, and acetaldehyde on aggressive behavior of the convict cichlid.

Ethanol and three beverage alcohols were examined for their effects on the aggressive responses of the convict cichlid. At an ethanol concentration that gave negligible effects on the basal level of these responses, rum was observed to depress aggression. As its concentration of acetaldehyde was significantly higher than that of the other beverage alcohols, we assessed the effects of acetaldehyde on the aggressive responses, as well as the locomotor activity of the fish. At 4 mg/l, acetaldehyde completely inhibited aggressive responses, without affecting locomotor activity. It is likely, however, that acetaldehyde does not explain the entire inhibitory effect of rum on the aggressive responses of the cichlid.

Combined effects of alcohol and sleep deprivation in normal young adults.

The effect of combining sleep deprivation and moderate alcohol consumption in male college students differed from the effects of each treatment alone. Following either alcohol or sleep deprivation, there was mild performance impairment, decreased alertness and reduced amplitude and increased latency of cortical evoked potential (EP) components. Heart rate increased after alcohol and anxiety increased after sleep deprivation. When alcohol and sleep deprivation were combined, antagonistic effects were found for most measures (reaction time, heart rate, alertness, anxiety, latency of early EP components), but synergistic effects also occurred (performance accuracy, latency of late EP components). These effects were found in a double-blind experiment using 24 subjects. The experimental treatments were alcohol doses of 0, 0.45 and 0.90 ml/kg of 95% ethanol and 0 and 26 h of sleep deprivation.

Motivational variables and the sensitization and habituation of aggression in the convict cichlid (Cichlasoma nigrofasciatum).

Four experiments using territorial Convict Cichlids investigated motivational factors involved in the incremental and decremental processes associated with aggression resulting from exposure to conspecifics intruded into the territory. The first three experiments varied some single aspect of the experimental situation (temperature, distance from the nest or size of the intruder). The fourth experiment combined those factors which resulted in faster habituation (small intruder, far from the nest, in cool water) and compared the response to factors which resulted in slower habituation or an increase in response rate (large intruder, close to the nest in warm water). While a combination of higher intensity stimuli did result in slower habituation than the combination of lower intensity stimuli, response rate was not a simple algebraic summation of the factors. Results are discussed in relation to multi-factor theory of habituation and the nature of "drive".

Effect of disulfiram on cognition, subjective response, and cortical-event-related potentials in nonalcoholic subjects.

The effect of 0.5 g of disulfiram per day for 2 wk on a battery of cognitive and cortical-event-related potential tasks was studied in healthy, nonalcoholic volunteers.

Effects of practice on marijuana-induced changes in reaction time.

The effect of smoked marijuana on performance of complex reaction time (RT) tasks was studied in two groups receiving different amounts of practice. Group M-P had no undrugged practice on the task before performing during marijuana intoxication for four consecutive daily sessions. On the fifth test day they performed while non-intoxicated. Group P-M performed the task on four consecutive test days while non-intoxicated, then smoked marijuana on session 5. Significant RT slowing was found on session 1 for group M-P (performing during marijuana intoxication without prior practice). Performance of this group improved rapidly and by the end of session 2 was not different from undrugged performance. Group P-M (receiving four sessions of undrugged practice before marijuana intoxication) showed no RT slowing while intoxicated. Reaction time performance may involve two phases: an early, attention-demanding phase which is sensitive to drug effects and a later, "automatic", phase which results from practice and is more resistant to drug effects. Pulse rate, salivary flow and subjective responses were recorded before and after smoking. These physiological and subjective measures showed only slight reduction in the acute effects of the drug over the four days of repeated usage.

Alcohol, habituation and the patterning of aggressive responses in a cichlid fish.

Territorial cichlids were presented for 30 min with a conspecific male intruder (contained in a clear glass tube). Eight hr prior, 2 groups were administered alcohol (0.15 or 0.30 percent in the aquaria water). A third group served as a control. Three responses were recorded to allow analysis of topographic changes in behavior as well as changes in absolute levels. During the habituation phase, the normal group showed a sequence of long displays, followed by shorter ones as the frequency of attacks increased. The occurrence of threat which gradually gives way to attack is characteristic of the agonistic behavior of this species. In contrast to the controls, the 0.15 percent group was hyperaggressive, while the 0.30 percent group was hypoaggressive. Furthermore, the patterning of responses were abnormal. The 0.15 percent group gave abbreviated threats and more attacks (interpreted as a tendency to attack without warning); whereas, the 0.30 percent group gave many long threat displays, but few attacks. A stimulus specificity test provided strong evidence that the waning found during the initial phase was habituation.

Relative frequency of attribute relevance and response times in visual search.

Two experiments, one using a between-Ss and one a within-Ss design, showed that response latencies to single attribute probe stimuli were longer when the target stimulus embodied two attributes (form and color) rather than a single attribute. The magnitude of this "mixed attribute effect" was influenced by the probability of attribute relevance, but the "probability effect" was mostly due to a "repetition effect," such that latencies on trials involving repetitions of the same attribute were shorter than when the relevant attribute was shifted. Implications of these results are drawn for the issues of holistic vs attributized representation of the target stimulus and serial vs parallel search of a set of attributes. Although no class of models can be ruled out on the basis of these experiments, constraints can be imposed on the versions of each that are compatible with the data presented.