Brent M. King

Effects of Induced Emotional State on Lexical Processing in Younger and Older Adults

Abstract The authors investigated the effects of an induced emotional mood state on lexical decision task (LDT) performance in 50 young adults and 25 older adults. Participants were randomly assigned to either happy or sad mood induction conditions. An emotional mood state was induced by having the participants listen to 8 min of classical music previously rated to induce happy or sad moods. Results replicated previous studies with young adults (i.e., sad-induced individuals responded faster to sad words and happy-induced individuals responded faster to happy words) and extended this pattern to older adults. Results are discussed with regard to information processing, aging, and emotion.

Alcohol-induced impairment and enhancement of memory: A test of the interference theory

Many studies have found cognitive deficits related to alcohol consumption. However, few studies have studied cognitive performance when alcohol was administered after the to-be-remembered information was presented with memory testing occurring when participants are once again sober. The present study examined effects of alcohol on cognitive performance using a prose recall task during acute intoxication and a post-trial recall task for prose passages that had been presented before intoxication. Fifty-one men were given either 2.0 g/kg of 100 proof (50% absolute ethanol) vodka or a placebo. In the present study, evidence was found of acute alcohol impairment in prose memory, along with alcohol facilitation of memory on a post-trial task.

Up or down: the influence of upcoming reinforcement on consummatory and operant behavior.

Abstract Research has shown that animal subjects that are given a chance to consume a low-valued substance will consume less of it if a high-valued substance will soon be available than they would if the low-valued substance were to remain available (negative consummatory contrast). Research has also shown that subjects that lever press for a low-valued reinforcer will press the lever more often for that reinforcer if they will soon be able to lever press for a high-valued reinforcer than they would if they continue to press for the low-valued reinforcer (positive induction). The present study investigated these different changes in behavior across 3 experiments. The results suggest that the occurrence of contrast or induction does not depend on the type of substances that are used. We argue that further investigation of the contrast vs. induction issue is warranted because it has empirical, theoretical, and applied implications.

Induction when rats lick for 1% liquid-sucrose reinforcement

Previous research reported that rats responding for 1% liquid-sucrose reinforcement when 32% sucrose reinforcement is upcoming will decrease their response rate (contrast) if licking is the dependent measure and increase their response rate (induction) if pressing a lever is the dependent measure. The present study investigated whether induction could be observed when licking served as the dependent measure and whether induction in lever pressing and contrast in licking behaviour could be concurrently observed. Experiment 1 found induction when rats licked to earn the rewards but consumed them at a location separate from the spout licked to earn them. Experiment 2 also found induction when rats earned (and consumed) rewards by licking the same spout throughout the session. Experiment 3 separately measured instrumental lever pressing for sucrose rewards and licking the sucrose during the reward period. We found that both measures increased for 1% sucrose when 32% sucrose reinforcement was upcoming. The present results indicate that the type of response is not the sole determinant of whether contrast or induction is observed. Rather, they suggest that other procedural details, such as the location of reinforcer delivery, influence which effect is observed. The results also indicate that associative processes underlie the appearance of induction in responding for 1% sucrose.

Rats’ Lever Pressing For 1% Sucrose and Food-Pellet Reinforcement: In Search of Negative Behavioral Contrast

The present study was undertaken to determine whether rats’ rates of lever pressing for 1 % liquid-sucrose reinforcement in the first component of a multiple schedule would display negative behavioral contrast (i.e., decreased responding) if food-pellet reinforcement replaced 1 % sucrose reinforcement in the second component. Previous research had demonstrated that instead of contrast, upcoming food-pellet reinforcement has produced positive induction (i.e., increased responding) in responding for 1% sucrose. However, the procedures which demonstrated induction deviated substantially from those known to favor the appearance of behavioral contrast. The present study manipulated procedural details toward those that favor contrast. Eight experiments were conducted, across which factors such as component discrimination, component duration, component alternation, baseline rate of reinforcement, and baseline rate of responding were altered. These alterations did not lead to the observance of negative contrast. In fact, they did litlle to alter the observance of positive induction. Across all experiments, positive induction was observed in 38 of 47 possible instances. The present results pose difficulties for many, if not all, of the existing theories of behavioral contrast. They also indicate that, under certain conditions, induction and not contrast is the reliable outcome.

RELEASE FROM PROACTIVE INTERFERENCE WITH POSITIVE AND NEGATIVE WORDS

Using the release from proactive interference (RPI) task, college students (n = 40) received 4 trials comprised of 3-word triads of either positive (P) or negative (N) words. Word-triad recall served as the dependent measure, and results revealed typical buildup of PI (i.e., no significant group x trial interaction across Trials 1–3). Significant RPI was also observed when examining performance across Trials 3–4, and PI release was greater in those subjects who experienced a valence shift from P words to N words or from N words to P words across Trials 3–4. No release was observed in the control group and the word-triad recall performance of the control group continued to decline across trials. Results are discussed in terms of using the RPI paradigm with emotionally valenced stimuli and including clinically relevant samples.

Does the Temporal Placement of Food-Pellet Reinforcement Alter Induction When Rats Respond on a Three-Component Multiple Schedule?

A series of recent studies have demonstrated that rats will increase their rate of operant responding for sucrose reinforcement when food-pellet reinforcement will be upcoming in the same session. One potential explanation for this increase is that operant, rather than respondent or general, behavior becomes increasingly probable in sessions in which food-pellet reinforcement will be available. This explanation implies that it is not necessarily upcoming food-pellet reinforcement that produces the induction. The present study investigated this implication by having rats press 1 lever (Experiment 1) or 3 different levers (Experiment 2) for 1 % liquid-sucrose reinforcers delivered by a 3-component multiple schedule. Across treatment conditions, food-pellet reinforcement replaced sucrose reinforcement in one of the three 15-min components. Doing so produced an induction effect in responding for sucrose in the other components. However, the size of induction did not differ depending on the temporal placement of the food-pellet reinforcement. These results are therefore consistent with the above, operant explanation.

Positive Induction is not a Function of “Timing”

Studies have shown that rats’ rates of lever pressing for low-concentration liquid-sucrose reinforcers in the first half of an experimental session are higher if food-pellet, rather than the same sucrose, reinforcement will be delivered in the second half. Experiment 1 investigated whether this induction effect would be altered if subjects were provided with an external “clock” (i.e., stimuli that changed as the period of food-pellet reinforcement approached). Induction was not altered by the clock. Experiment 2 investigated whether subjects’ might be internally timing the upcoming food pellets. Subjects responded in sessions in which pressing the left and right lever was reinforced in the first and second half, respectively, of the session and the switch in reinforcement between halves was unsignaled. Delivering foodpellet reinforcement in one half of the session altered the timing functions, but induction in responding for 1 % sucrose was still observed. Experiment 3 investigated whether induction might then be the result of a disruption in timing. It partially replicated the procedure of Experiment 2, but also had subjects respond in conditions in which timing the switch in reinforcement between halves was not necessary. Similar results were observed across conditions in which timing was and was not required. These results question the idea that timing is involved in the appearance of induction. They suggest that some other mechanism, such as a change in the value of the sucrose, is behind the effect.