Incubation and the persistence of fixation in problem solving

Extra work on unsolved problems may lead to more improvement if the new work is delayed rather than undertaken immediately after initial solution attempts. Such a result constitutes incubation in problem solving. "Unconscious work" on a problem, commonly assumed to be responsible for incubation effects, may not be necessary to observe the phenomenon. We hypothesize that fixation, a block to successful problem solving, may develop during initial solution attempts and persist, interfering with immediate extra work more than with delayed extra work. Five experiments are reported in which fixation was induced to prevent optimal performance on the initial test of Remote Associates Test (RAT) problems (e.g., Mednick, 1962). After the fixation manipulation in three of the experiments, the effects of incubation intervals were examined by retesting the fixated problems. Both fixation (poorer initial problem-solving performance) and incubation (more improvement after a delayed retest than an immediate retest) were found in all the experiments which tested for the effects. In Experiments 1, 2, and 3, misleading distractors were presented alongside the RAT problems during the initial test of the problems to cause fixation. In Experiment 4, a block of paired associates--pairing the RAT words with the misleading distractors prior to problem solving--successfully induced fixation, indicating that the distractors affected memory retrieval. In Experiment 5, a trial-by-trial technique allowed fixation and incubation to be induced and tested separately for each item. All of our findings of incubation effects appear to have depended upon the initial induction of fixation. Although the experiments may not be representative of all naturally occurring cases of incubation, they provide a methodology for the study of fixation and incubation effects in problem solving in the laboratory.     

The Role of an Incubation Period in Creative Problem Solving

ABSTRACT

This experimental study tested the spreading-activation hypothesis that an incubation period helps to sensitize problem solvers to relevant concepts. The study also tested the selective forgetting hypothesis that an incubation period helps to desensitize problem solvers to irrelevant concepts. Chinese Chess GO players, 28 experts and 29 novices, solved 18 remote association tasks (RAT) and lexical decision tasks (LDTs) under immediate, rest, and incubation conditions. After each RAT, a set of LDTs incorporating the RAT solution and the irrelevant concept were presented, either immediately, or after a 2-min delay, or after a 2-min delay filled with incubation tasks. The findings of the study support the spreading activation hypothesis and suggest that spreading activation occurs only in a fixated mind. No support was found for the selective forgetting hypothesis.     

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.     

Interrupted: The roles of distributed effort and incubation in preventing fixation and generating problem solutions

Fixation on inappropriate concepts is a key barrier to problem solving. Previous research has shown that continuous work is likely to cause repeated retrieval of those concepts, resulting in increased fixation. Accordingly, distributing effort across problems through multiple, brief, and interlaced sessions (distributed effort) should prevent such fixation and in turn enhance problem solving. This study examined whether distributed effort can provide an advantage for problem solving, particularly for problems that can induce fixation (Experiment 1), and whether and how incubation can be combined with distributed effort to further enhance performance (Experiment 2). Remote Associates Test (RAT) problems were used as the problem-solving tasks. Half of them (i.e., misleading RAT) were more likely to mislead individuals to fixate on incorrect associates than the other half. Experiments revealed a superiority of distributed over massed effort on misleading RAT performance and a differing time course of incubation for the massed and distributed groups. We conclude that distributed effort facilitates problem solving, most likely via overcoming fixation. Cognitive mechanisms other than the commonly posited forgetting of inappropriate ideas may occur during incubation to facilitate problem solving. The experiments in this article offer support for the occurrence of spreading activation during incubation.     

Incubation benefits only after people have been misdirected

Incubation refers to the popular idea that stopping work on a problem may, at times, be a more efficient means by which to reach a solution than continuing to work. Empirical studies of incubation have used few participants and have provided ambiguous and discrepant results. We investigated three potential accounts of incubation in retrieval and search problems (subconscious work, spreading activation, and fixation forgetting) with the help of a large Internet-based participant pool. The amount of time allotted for explicit work on each of 12 problems was controlled, while the distribution of that time was manipulated in several incubation conditions. When problems were presented by themselves, none of the incubation conditions aided in the solution of either anagram or remote associate test problems. However, incubation benefits arose when participants were given misdirecting clues (probably because time delays facilitated forgetting of these clues).     

The Experience of Insight Follows Incubation in the Compound Remote Associates Task

The phenomenon of insight is frequently characterized by the experience of a sudden and certain solution. Anecdotal accounts suggest that insight frequently occurs after the problem solver has taken some time away from the problem (i.e., incubation). However, the mechanism by which incubation may facilitate insight problem‐solving remains unclear. Here, we used compound remote associates problems to explore the likely mechanisms by which incubation may facilitate problem‐solving. First, we manipulated problem fixation to explore whether forgetting can explain incubation effects. Second, leveraging previous work linking the experience of insight to unconscious semantic integration, we asked participants to report their experience of insight after each problem solution, including problems solved after a period of distracted incubation. We hypothesized that incubation was not principally important for forgetting but rather frequently causes a shift to a more unconscious semantic integration strategy. Consistent with this we found that initial problem fixation did not predict the improvement in problem‐solving after incubation and that participants were more likely to report insight on problems solved after incubation. Our findings suggest that incubation may facilitate insight problem‐solving leading to a mind‐set shift to a more unconscious problem‐solving strategy involving semantic integration.     

Effects of a Daytime Nap on Primed and Repeated Remote Associates Tests and Relations with Divergent Creativity

The effect of napping versus wakefulness was studied on primed and repeated Remote Associate Tests (RATs) and on divergent creativity tests. The participants were 42 students from the USA, studying international courses at a Swedish university. The hypotheses for the RATs were (1), when the correct answers were primed before the nap, the RAT should be solved better for those who entered REM sleep, compared to those with no REM sleep or a resting condition; and (2), when retested the RAT should be solved better after a nap than after rest. For the creativity tests, hypothesis (3) was that creativity should be higher after the nap than after rest. Hypothesis 1 and hypothesis 3 were not supported. Hypothesis 2 was supported in an ANOVA. The REM group improved more than the rest group on the repeated RAT. Also, the No-REM and rest groups differed, strengthening the importance of both REM and No-REM sleep for creative problem-solving.     

Nonuniform effects of reinstatement within the time window

A time window is a limited period after an event initially occurs in which additional information can be integrated with the memory of that event. It shuts when the memory is forgotten. The time window hypothesis holds that the impact of a manipulation at different points within the time window is nonuniform. In two operant conditioning experiments with 68 3-month-old human infants, we tested the predictive validity of the nonuniformity principle for reinstatement—a partial training trial that forestalls forgetting. After demonstrating that 3-month-olds forget the training task after 5 days (Experiment 1), we presented a reinstatement early (immediately), midway (3 days), or late (5 days) in the time window (Experiment 2). Retention increased exponentially with the reinstatement delay. The surprising magnitude of this result, plus its generality across tasks and species, strongly suggests that the timing of reinstatement differentially affects the outcomes of studies on learning and memory.     

Thinking can cause forgetting: memory dynamics in creative problem solving

Research on retrieval-induced forgetting has shown that retrieval can cause the forgetting of related or competing items in memory (Anderson, Bjork, & Bjork, 1994). In the present research, we examined whether an analogous phenomenon occurs in the context of creative problem solving. Using the Remote Associates Test (RAT; Mednick, 1962), we found that attempting to generate a novel common associate to 3 cue words caused the forgetting of other strong associates related to those cue words. This problem-solving-induced forgetting effect occurred even when participants failed to generate a viable solution, increased in magnitude when participants spent additional time problem solving, and was positively correlated with problem-solving success on a separate set of RAT problems. These results implicate a role for forgetting in overcoming fixation in creative problem solving.     

Alternating Incubation Effects in the Generation of Category Exemplars

Four experiments tested the forgetting fixation hypothesis of incubation effects, comparing continuous vs. alternating generation of exemplars from three different types of categories. In two experiments, participants who listed as many members as possible from two different categories produced more responses, and more novel responses, when they alternated back and forth between the two categories, as compared to continuous uninterrupted listing from each of the two categories. This incubation effect was not found in Experiment 1, when participants were given taxonomic categories (birds and clothing ) for the generation task, but was found in Experiment 2 with sense impression categories (cold things and heavy things ), and in Experiment 3 with ad hoc categories (equipment you take camping and fattening foods ). A similar incubation effect was observed in Experiment 4 when a non‐verbal task was given between category generation tasks, but only for flexibly defined categories. The results suggest that forgetting from one alternating listing period to the next in the form of altering category cue representations was consistent with the observed incubation effects. These alternating incubation effects have implications for understanding cognitive processes that underlie creative cognition.     

Destructive effects of “forget” instructions

In two experiments, participants were given three lists of words to study and were told to (1) remember all three lists, (2) forget the first list immediately after studying it but try to remember the other two lists, or (3) forget the middle list immediately after studying it but try to remember the first and the last lists. In Experiment 1, unrelated word lists were used, whereas Experiment 2 replicated Experiment 1 with categorical lists. The results from both experiments showed that forgetting the middle list leads also to recall decrement for the first list, which was not intended for forgetting. The results are discussed in terms of the contextual change hypothesis of directed forgetting.     

The Use of Environmental Clues During Incubation

ABSTRACT: Three experiments tested the prediction that incubation effects are caused by interactions between activation and environmental clues. Participants worked on 20 experimental problems and then were informed that they would have a second chance to work on the problems. Half were told they might see clues before returning to the problems and were instructed to try to use such clues. Participants then had an incubation period during which they generated words from the letters of test words. The test words were either semantically related to experimental problem answers, the actual answers, or unrelated words. Finally, all participants again tried to solve the experimental problems. Resolution, calculated as the number of items solved during the second trial that were not solved initially, was measured. Participants who saw answers during incubation resolved more items than those who saw related words. In Experiment 3, participants receiving no instructions did not differ across clue conditions, whereas instructed participants who saw answers resolved more problems than those who received related words. Participants in the instructed and unrelated condition performed significantly worse than those in the instructed and answer condition. Incubation effects occurred only when participants who were shown answers were also given instructions. No support was found for the theory that incubation effects are caused solely by environmental clues and activation.     

Similarity of encoding context does not influence resistance to memory impairment following misinformation

Several recent studies have shown that exposure to verbal misleading post-event information does not impair subjects' ability to retrieve originally seen details. Two experiments were conducted to test the hypothesis that subjects would be more susceptible to memory impairment if the original and misleading information were presented in similar contextual formats. The results showed that misleading information did not lead to memory impairment when both original and misleading information were presented in the context of slides (Experiment 1) or when both original and misleading information were presented in the context of narratives (Experiment 2). Furthermore, resistance to memory impairment was observed both at relatively low levels of memory for the original information (Experiment 1) and at relatively high levels of memory for the original information (Experiment 2). The implications of the present results for interference principles of forgetting are discussed.     

The merits of unconscious thought in creativity

Research has yielded weak empirical support for the idea that creative solutions may be discovered through unconscious thought, despite anecdotes to this effect. To understand this gap, we examined the effect of unconscious thought on two outcomes of a remote-association test (RAT): implicit accessibility and conscious reporting of answers. In Experiment 1, which used very difficult RAT items, a short period of unconscious thought (i.e., participants were distracted while holding the goal of solving the RAT items) increased the accessibility of RAT answers, but did not increase the number of correct answers compared with an equal duration of conscious thought or mere distraction. In Experiment 2, which used moderately difficult RAT items, unconscious thought led to a similar level of accessibility, but fewer correct answers, compared with conscious thought. These findings confirm and extend unconscious-thought theory by demonstrating that processes that increase the mental activation of correct solutions do not necessarily lead them into consciousness.     

Enhanced recognition and recall of new words in 7- and 12-year-olds following a period of offline consolidation

Recent studies of adults have found evidence for consolidation effects in the acquisition of novel words, but little is known about whether such effects are found developmentally. In two experiments, we familiarized children with novel nonwords (e.g., biscal) and tested their recognition and recall of these items. In Experiment 1, 7-year-olds were then retested on either the same day or the following day to examine changes in performance after a short delay compared with a longer delay that included sleep. Experiment 2 used two age groups (7- and 12-year-olds), with all participants being retested 24h later. The 12-year-olds accurately recognized the novel nonwords immediately after exposure, as did the 7-year-olds in Experiment 2 (but not in Experiment 1), suggesting generally good initial rates of learning. Experiment 1 revealed improved recognition of the novel nonwords after both short (3- to 4-h) and longer (24-h) delays. In contrast, recall was initially poor but showed improvements only when children were retested 24h later, not after a 3- to 4-h delay. Similar improvements were observed in both age groups despite better overall performance in 12-year-olds. We argue that children, like adults, exhibit offline consolidation effects on the formation of novel phonological representations.     

The impact of different directed forgetting instructions on implicit and explicit memory: New evidence from a modified process dissociation procedure

In contrast to previous research on directed forgetting, the present studies adopted a recent modification of the process dissociation procedure (Jacoby, 1991; Richardson-Klavehn & Gardiner, 1995) to accommodate the cross-contamination of memory test performance by implicit and explicit memorial factors. In Experiment 1, 120 subjects were compared in global directed forgetting, item-by-item directed forgetting, and control conditions on estimates of voluntary conscious memory, involuntary conscious memory, and involuntary unconscious memory performance. In Experiment 2, 80 subjects were compared in specific directed forgetting and control conditions on estimates of voluntary conscious memory, involuntary conscious memory, and involuntary unconscious memory performance. Subjects showed significant decrements in voluntary and involuntary conscious memory performance following instructions for directed forgetting in all conditions. None of the directed forgetting conditions showed a decrement in involuntary unconscious memory performance. Results suggest that, regardless of instruction type, directed forgetting prevents the conscious expression of memorial information (both voluntary and involuntary) while leaving unconscious memory intact.     

A multidimensional approach to skilled perception and performance in sport

Three experiments examined the relative importance of attributes determined largely by the efficiency of the visual/central nervous system versus cognitive domain‐specific skills, in the determination of expertise in soccer. In Experiment 1, expert and intermediate soccer players were assessed on various non‐specific abilities including: processing (simple reaction time, peripheral reaction time, visual correction time), optometric (static, dynamic and mesopic acuity), and perimetric parameters (horizontal and vertical peripheral range). In Experiment 2, domain‐specific variables were assessed including complex decision speed and accuracy, number of visual fixations, fixation duration, and fixation location in solving game problems. Stimuli were initially presented by slides (Experiment 2) and later by 16 mm film (Experiment 3). Eye movements were recorded and analysed. A stepwise discriminant analysis of both non‐specific abilities and soccer‐specific skills revealed an average squared canonical correlation=0.84, with the significant step variables all being domain‐specific skills. Copyright © 1999 John Wiley & Sons, Ltd.     

Eye movement control during scene viewing: Immediate degradation and enhancement effects of spatial frequency filtering

What controls how long the eyes remain fixated during scene perception? We investigated whether fixation durations are under the immediate control of the quality of the current scene image. Subjects freely viewed photographs of scenes in preparation for a later memory test while their eye movements were recorded. Using the saccade-contingent display change method, scenes were degraded (Experiment 1) or enhanced (Experiment 2) via blurring (low-pass filtering) during predefined saccades. Results showed that fixation durations immediately after a display change were influenced by the degree of blur, with a monotonic relationship between degree of blur and fixation duration. The results also demonstrated that fixation durations can be both increased and decreased by changes in the degree of blur. The results suggest that fixation durations in scene viewing are influenced by the ease of processing of the image currently in view. The results are consistent with models of saccade generation in scenes in which moment-to-moment difficulty in visual and cognitive processing modulates fixation durations.     

Orthographic familiarity influences initial eye fixation positions in reading

An important issue in the understanding of eye movements in reading is what kind of nonfoveal information can influence where we move our eyes. In Experiment 1, first fixation landing positions were nearer the beginning of misspelled words. Experiment 2 showed that the informativeness of word beginnings does not influence where words are first fixated. In both experiments, refixations were more likely to be to the left of the initial fixation position if the words were misspelled. Also, there was no influence of spelling on prior fixation durations or refixation probabilities, that is, there was no evidence for parafoveal‐on‐foveal effects. The results show that the orthographic familiarity, but not informativeness, of word initial letter sequences influences where words are first fixated.     

Eyewitness memory for a simulated misdemeanor crime: the role of age and temperament in suggestibility

The timing of misleading questions within an interview (immediate, 7‐week delay) and temperament characteristics as correlates of suggestibility were examined in two experiments. In Experiment 1, 6/7‐year‐olds, 9/10‐year‐olds, and adults were given general‐to‐specific questions at both intervals or misleading questions initially and general‐to‐specific questions at delay. In Experiment 2, 4/5‐year‐olds, 9/10‐year‐olds, and adults were given general‐to‐specific questions at both intervals or general‐to‐specific questions initially and misleading questions at delay. Introducing misleading questions in the initial interview increased suggestibility for peripheral features, whereas suggestibility for central features was found when misleading questions were asked in the delayed interview. Age changes in recall and elaboration for categorical information were found. Some temperament characteristics were associated with age‐related changes in compliance and suggestibility. Copyright © 2005 John Wiley & Sons, Ltd.