How motor practice shapes memory: retrieval but not extra study can cause forgetting

We investigated the retrieval specificity of retrieval-induced forgetting (RIF) of motor sequences. In two experiments, participants learned sequential finger movements, each consisting of the movement of two fingers of either the left or the right hand. In the learning phase, these motor sequences were graphically presented and were to be learned as responses to simultaneously presented letter stimuli. Subsequently, participants selectively practiced half the items of one hand. A final recall test then assessed memory for all initially learned items. We contrasted different kinds of selective practice with each other. Whereas retrieval practice required retrieving motor sequences in response to letter stimuli from the learning phase, extra study was an extension of the learning phase, that is, participants performed motor sequences in response to the same animation graphic display as in the learning phase again accompanied by the letter stimulus. All practice conditions strengthened the practiced items, but only retrieval practice resulted in RIF. Thus, the strengthening of items through practice did not suffice to induce forgetting of related motor sequences. Retrieval was a necessary component for practice to shape memory for body movements by impairing the subsequent recall of motor sequences that were related to the practiced motor sequences.     

Semantic generation can cause episodic forgetting

The repeated retrieval of a subset of previously learned items can cause forgetting of the nonretrieved items. The study reported here investigated whether retrieval-induced forgetting generalizes to a situation in which the retrieved and nonretrieved items are not part of the same experiential episode and task. Subjects learned an item list that they had to recall later in the experiment. In a separate intermediate phase, they repeatedly generated related items from semantic memory, or were presented the same items intact for study. Only the semantic generation of items, and not their presentation for study, induced forgetting of the initially learned items. This result indicates that, first, semantic generation can cause recall-specific episodic forgetting and, second, retrieval-induced forgetting can occur even if the retrieved and nonretrieved items belong to different experiential episodes and tasks. Connections of the present results to other memory phenomena, such as part-set cuing and the generation effect, social cognition, and eyewitness memory, are discussed.     

Episodic generation can cause semantic forgetting: Retrieval-induced forgetting of false memories

In two experiments, we tested whether false recognition and false recall were prone to retrieval-induced forgetting, using the retrieval practice paradigm (Anderson, Bjork, & Bjork, 1994). Participants encoded lists of cue-target word pairs associated with a nonpresented, critical theme word and then engaged in retrieval practice for half of the word pairs from half of the lists. As expected, unpracticed targets from practiced lists were recognized (Experiment 1) and recalled (Experiment 2) less well than those from unpracticed lists. In addition, false recognition and false recall of critical items associated with practiced lists was lower than false recognition and false recall of items associated with unpracticed lists. We argue that false memories are prone to inhibitory mechanisms engendered by the retrieval practice paradigm. The results are consistent with the claim that semantically activated critical themes interfere with the episodic retrieval of list words and that inhibition decreases the activation level of these interfering memory representations during retrieval practice.     

Modal preferences in creative problem solving

Embodied cognitive science appeals to the idea that cognition depends on the body as well as on the brain. This study looks at whether we are more likely to engage just the brain or enlist the body for complex cognitive functioning such as creative problem solving. Participants were presented with a puzzle based on De Bono's lateral thinking puzzles. The puzzle consisted of rotating and joining two-dimensional shapes to make a three-dimensional one. In one condition, participants were given the choice of either solving the puzzle mentally or through manipulation of the images on a computer screen. In another condition, the subjects had to solve the puzzle first mentally and then report which mode they would have preferred to solve the puzzle. Two more conditions were applied with slight variations. In all conditions, an overwhelming majority of participants chose to solve the puzzle by manipulation, even though there was not a significant increase on performance. It appeared that participants were making a conscious choice for the body to play a feedback-driven role in creative cognitive processing. This strong preference for manual manipulation over just mental representation, regardless of the impact on performance, would seem to suggest that it is our natural tendency to involve the body in complex cognitive functioning. This would support the theory that cognition may be more than just a neural process, and that it is a dynamic interplay between body, brain and world. The experiential feedback of the body moving through space and time may be an inherently important factor in creative cognition.     

Modal preferences in creative problem solving

Embodied cognitive science appeals to the idea that cognition depends on the body as well as on the brain. This study looks at whether we are more likely to engage just the brain or enlist the body for complex cognitive functioning such as creative problem solving. Participants were presented with a puzzle based on De Bono’s lateral thinking puzzles. The puzzle consisted of rotating and joining two-dimensional shapes to make a three-dimensional one. In one condition, participants were given the choice of either solving the puzzle mentally or through manipulation of the images on a computer screen. In another condition, the subjects had to solve the puzzle first mentally and then report which mode they would have preferred to solve the puzzle. Two more conditions were applied with slight variations. In all conditions, an overwhelming majority of participants chose to solve the puzzle by manipulation, even though there was not a significant increase on performance. It appeared that participants were making a conscious choice for the body to play a feedback-driven role in creative cognitive processing. This strong preference for manual manipulation over just mental representation, regardless of the impact on performance, would seem to suggest that it is our natural tendency to involve the body in complex cognitive functioning. This would support the theory that cognition may be more than just a neural process, and that it is a dynamic interplay between body, brain and world. The experiential feedback of the body moving through space and time may be an inherently important factor in creative cognition.     

Positive affect facilitates creative problem solving

Four experiments indicated that positive affect, induced by means of seeing a few minutes of a comedy film or by means of receiving a small bag of candy, improved performance on two tasks that are generally regarded as requiring creative ingenuity: Duncker's (1945) candle task and M. T. Mednick, S. A. Mednick, and E. V. Mednick's (1964) Remote Associates Test. One condition in which negative affect was induced and two in which subjects engaged in physical exercise (intended to represent affectless arousal) failed to produce comparable improvements in creative performance. The influence of positive affect on creativity was discussed in terms of a broader theory of the impact of positive affect on cognitive organization.     

Escaping mental fixation: Incubation and inhibition in creative problem solving

The inhibition underlying retrieval-induced forgetting has been argued to play a crucial role in the ability to overcome interference in memory and cognition. Supporting this conjecture, recent research has found that participants who exhibit greater levels of retrieval-induced forgetting are better at overcoming fixation on the Remote Associates Test (RAT) than are participants who exhibit reduced levels of retrieval-induced forgetting. If the ability to inhibit inappropriate responses improves the ability to solve fixated RAT problems, then reducing the fixation caused by inappropriate responses should reduce the correlation between retrieval-induced forgetting and problem solving. We tested this hypothesis by inserting an incubation period between two 30-second problem-solving attempts: half of the participants were given an incubation period (distributed condition), half were not (continuous condition). In the continuous condition retrieval-induced forgetting correlated positively with problem-solving performance during both the initial and final 30 seconds of problem solving. In the distributed condition retrieval-induced forgetting only correlated with problem-solving performance during the first 30 seconds of problem solving. This finding suggests that incubation reduces the need for inhibition by reducing the extent to which problem solvers suffer fixation.     

Selective cues to forget can fail to cause forgetting

Recent research has found that individuals can selectively forget a subset of items through directed forgetting. The goal of the present study was to replicate this selective directed forgetting effect and elucidate its underlying mechanisms. Unfortunately, results from four experiments failed to find any evidence of selective directed forgetting. Participants failed to forget any items when instructed to forget a subset of items from a first list before learning a second list. Participants were only successful in forgetting items from the first list when they were instructed to forget all items from the first list before learning the second list.     

Uncorking the muse: alcohol intoxication facilitates creative problem solving

That alcohol provides a benefit to creative processes has long been assumed by popular culture, but to date has not been tested. The current experiment tested the effects of moderate alcohol intoxication on a common creative problem solving task, the Remote Associates Test (RAT). Individuals were brought to a blood alcohol content of approximately .075, and, after reaching peak intoxication, completed a battery of RAT items. Intoxicated individuals solved more RAT items, in less time, and were more likely to perceive their solutions as the result of a sudden insight. Results are interpreted from an attentional control perspective.     

The effects of expected reward on creative problem solving

Creative problem solving involves search processes, and it is known to be hard to motivate. Reward cues have been found to enhance performance across a range of tasks, even when cues are presented subliminally, without being consciously detected. It is uncertain whether motivational processes, such as reward, can influence problem solving. We tested the effect of supraliminal and subliminal reward on participant performance on problem solving that can be solved by deliberate analysis or by insight. Forty-one participants attempted to solve 100 compound remote associate problems. At the beginning of each problem, a potential reward cue (1 or 25 cents) was displayed, either subliminally (17 ms) or supraliminally (100 ms). Participants earned the displayed reward if they solved the problem correctly. Results showed that the higher subliminal reward increased the percentage of problems solved correctly overall. Second, we explored if subliminal rewards preferentially influenced solutions that were achieved via a sudden insight (mostly processed below awareness) or via a deliberate analysis. Participants solved more problems via insight following high subliminal reward when compared with low subliminal reward, and compared with high supraliminal reward, with no corresponding effect on analytic solving. Striatal dopamine (DA) is thought to influence motivation, reinforce behavior, and facilitate cognition. We speculate that subliminal rewards activate the striatal DA system, enhancing the kinds of automatic integrative processes that lead to more creative strategies for problem solving, without increasing the selectivity of attention, which could impede insight.     

Chasing red herrings: Memory of distractors causes fixation in creative problem solving

Two experiments tested the red herring retrieval hypothesis, which states that fixation in creative problem solving is worse when memory for red herrings (i.e., inappropriate or incorrect solutions) is strengthened. In Experiment 1, when associations between Remote Associates Test (RAT) problem words (e.g., COTTAGE, SWISS, CAKE) and related red herring words (e.g., hut, chocolate, icing) were strengthened via repetition, an encoding variable, fixation was found to increase. In Experiment 2, when associations were formed between RAT problem contexts and red herrings, then subsequent reinstatement of problem contexts during RAT problem solving trials (as compared with showing new contexts) also worsened fixation effects. Our results add to the increasing body of research that connects memory with creative problem solving, and they suggest possible ways for overcoming fixation effects.     

Unconscious processing modulates creative problem solving: Evidence from an electrophysiological study

Previous behavioral studies have identified the significant role of subliminal cues in creative problem solving. However, neural mechanisms of such unconscious processing remain poorly understood. Here we utilized an event-related potential (ERP) approach and sandwich mask technique to investigate cerebral activities underlying the unconscious processing of cues in creative problem solving. College students were instructed to solve divergent problems under three different conditions (conscious cue, unconscious cue and no-cue conditions). Our data showed that creative problem solving can benefit from unconscious cues, although not as much as from conscious cues. More importantly, we found that there are crucial ERP components associated with unconscious processing of cues in solving divergent problems. Similar to the processing of conscious cues, processing unconscious cues in problem solving involves the semantic activation of unconscious cues (N280–340) in the right inferior parietal lobule (BA 40), new association formation (P350–450) in the right parahippocampal gyrus (BA 36), and mental representation transformation (P500–760) in the right superior temporal gyrus (BA 22). The present results suggest that creative problem solving can be modulated by unconscious processing of enlightening information that is weakly diffused in the semantic network beyond our conscious awareness.     

Counting on working memory in arithmetic problem solving

Mental calculation is an important everyday skill involving access to well-learned procedures, problem solving, and working memory. Although there is an active literature on acquiring concepts and procedures for mental arithmetic, relatively little is known about the role of working memory in this task. This paper reports two experiments in which dual-task methodology is used to study the role of components of working memory in mental addition. In Experiment 1, mental addition of auditorily presented two-digit numbers was significantly disrupted by concurrent random letter generation and, to a lesser extent, by concurrent articulatory suppression, but was unimpaired by concurrent hand movement or by presentation of irrelevant pictures. Although the number of errors increased with two of the dual tasks, the incorrect responses tended to be quite close to the correct answer. In Experiment 2, the numbers for addition were presented visually. Here again, random generation produced the largest disruption of mental arithmetic performance, while a smaller amount of disruption was observed for articulatory suppression, hand movement, and unattended auditorily presented two-digit numbers. The overall levels of performance were better and the absolute size of the disruptive effects shown with visual presentation was very small compared with those found for auditory presentation. This pattern of results is consistent with a role for a central executive component of working memory in performing the calculations required for mental addition and in producing approximately correct answers. Visuospatial resources in working memory may also be involved in approximations. The data support the view that the subvocal rehearsal component of working memory provides a means of maintaining accuracy in mental arithmetic, and this matches a similar conclusion derived from previous work on counting. The general implications for the role of working memory in arithmetic problem solving will be discussed.     

Distributing working memory resources during problem solving

This study examines how problem solvers distribute working memory demands over internal and external resources. Participants recorded notes while performing an arithmetic task. They recorded a majority of intermediate results and labeled many of those results (e.g., "C = 10"). When more effort was required to take notes, participants recorded fewer results. Participants with a consistent goal structure recorded fewer results and with practice labeled fewer recorded results than those with varied goal structures. When notes were displayed in a consistent spatial arrangement participants labeled fewer recorded results than when notes appeared in varied locations. These findings indicate that individuals use explicit and implicit strategies for indexing intermediate results. The data support the view that individuals flexibly distribute working memory over internal and external resources in response to situational cost-benefit considerations.     

Expertise as mental set: The effects of domain knowledge in creative problem solving

Experts generally solve problems in their fields more effectively than novices because their wellstructured, easily activated knowledge allows for efficient search of a solution space. But what happens when a problem requires a broad search for a solution? One concern is that subjects with a large amount of domain knowledge may actually be at a disadvantage, because their knowledge may confine them to an area of the search space in which the solution does not reside. In other words, domain knowledge may act as a mental set, promoting fixation in creative problem-solving attempts. A series of three experiments in which an adapted version of Mednick’s (1962) remote associates task was used demonstrates conditions under which domain knowledge may inhibit creative problem solving.     

Percolating ideas: The effects of caffeine on creative thinking and problem solving

Caffeine is the most widely consumed psychotropic drug in the world, with numerous studies documenting the effects of caffeine on people’s alertness, vigilance, mood, concentration, and attentional focus. The effects of caffeine on creative thinking, however, remain unknown. In a randomized placebo-controlled between-subject double-blind design the present study investigated the effect of moderate caffeine consumption on creative problem solving (i.e., convergent thinking) and creative idea generation (i.e., divergent thinking). We found that participants who consumed 200 mg of caffeine (approximately one 12 oz cup of coffee, n = 44), compared to those in the placebo condition (n = 44), showed significantly enhanced problem-solving abilities. Caffeine had no significant effects on creative generation or on working memory. The effects remained after controlling for participants’ caffeine expectancies, whether they believed they consumed caffeine or a placebo, and changes in mood. Possible mechanisms and future directions are discussed.     

Working memory demands in insight versus analytic problem solving

Working memory is one of the cognitive processes thought to differentiate insight and analytic forms of problem solving. The present research examined memory involvement in the solution of insight versus analytic problems. Participants completed verbal and spatial working memory and short-term memory measures and a series of analytic and insight problems. Results demonstrated a relationship between working-memory capacity and the solution of analytic problems and between verbal short-term memory capacity and the solution of insight problems. This distinction was generally though not universally supported when memory was examined in relation to individual problems. Memory involvement in insight problem solving was further examined to clarify whether restructuring in insight is the end result of active memory search or spontaneous processes. The present research supports the theory that differences exist in the cognitive processes underlying insight versus analytic problem solving, and provides support for the spontaneous theory of restructuring in insight.