Copyright 2003 Psychonomic Society, Inc. 730

Psychonomic Bulletin & Review

2003, 10 (3), 730-737

Most people have had the Aha! experience of insight

many times for trivial problems such as riddles or crossword

clues or when, at long last, they achieve a deep understanding

of a vexing problem. However, because it depends

so heavily on subjective experience, a deeper understanding

of the processes underlying insight has been elusive.

Researchers agree that when trying to solve an insight problem

solvers (1) come to an impasse, perhaps because they

are misled by ambiguous information in the problem (Dominowski

& Dallob, 1995; Smith 1995); (2) often cannot report

the processing that enables them to overcome this impasse

(Gick & Lockhart, 1995; Ohlsson, 1992; Schooler &

Melcher, 1995); and (3) experience their solutions as sudden

and surprising (Bowden, 1997; Davidson, 1995; Metcalfe,

1986a, 1986b; Metcalfe & Wiebe, 1987; Schooler,

Ohlsson, & Brooks, 1993).

The experience of insight has been examined with

feeling-of-knowing ratings, warmth ratings, and intuitions

(Bowden, 1997; Davidson, 1995; Dorfman, Shames, &

Kihlstrom, 1996; Metcalfe, 1986a, 1986b; Metcalfe &

Wiebe, 1987; Seifert, Meyer, Davidson, Patalano, & Yaniv,

1995). These approaches have helped characterize the insight

experience, yet each has the shortcoming of relying

solely on participants’ subjective reports. The present experiment

links participants’ subjective judgments of insight

with an objective measure of processing: specifically,

priming for the solution.

Subjective Experience of Insight

When people attempt to solve noninsight problems,

they generally give gradually increasing warmth ratings,

indicating that they believe they are approaching a solution

(warmth is a measure of how close one feels one is to

reaching a solution); in contrast, when people attempt to

solve insight problems, they report no change in warmth

until immediately before solving the problem, when feelings

of warmth increase dramatically (Metcalfe, 1986a).

This pattern may be interpreted as supporting the ideas

that solving insight problems requires reinterpretation of

these problems and that solving such problems can sometimes

(but not always) be relatively easy once the correct

solution path is chosen (Schooler, Fallshore, & Fiore, 1995).

Furthermore, solvers are better at predicting whether they

will eventually achieve solutions of noninsight problems

than they are at predicting solutions of insight problems

(Metcalfe & Wiebe, 1987), possibly due to initial misinterpretation

of the problem.

Why do problem solvers sometimes have the Aha! experience

of insight upon reaching a solution? Solvers seem

to experience insight when they suddenly overcome an impasse

as a result of some unconscious processing, often

termed

restructuring(for a review, see Dominowski & Dallob,

1995), but this begs the question of how restructuring

occurs. Verbalizing solution attempts can actually impede

Research and writing were supported by NIDCD/NIH Grants R29 DC

02160 and R01 DC 04052 to M.J.B. Data were collected while both authors

were at Rush Medical College, Chicago, IL. Correspondence concerning

this article should be addressed to E. M. Bowden or M. Jung-

Beeman, Department of Psychology, Northwestern University, 2029

Sheridan Rd., Evanston, IL 60208-2710 (e-mail: e-bowden@northwestern.

edu or [email protected]).

Aha! Insight experience correlates with solution

activation in the right hemisphere

EDWARD M. BOWDEN and MARK JUNG-BEEMAN

Northwestern University, Evanston, Illinois

In one experiment, we tested for an association between semantic activation in the right hemisphere

(RH) and left hemisphere (LH) and the Aha! experience when people recognize solutions to insight-like

problems. The compound remote associate problems used in this experiment sometimes evoke an Aha!

experience and sometimes do not. On each trial, participants (

N = 44) attempted to solve these problems

and, after 7 sec, named a target word, made a solution decision, and rated their insight experience

of recognizing the solution. As in prior studies, the participants demonstrated more solution priming

for solutions presented to the left visual field-RH (lvf-RH) than for solutions presented to the right visual

field-LH (rvf-LH). As was predicted, following unsolved problems the participants showed greater

priming for solutions that they rated as evoking an insight experience on the subsequent solution decision

than for solutions that did not evoke an insight experience. This association was stronger for solutions

presented to the lvf-RH than for those presented to the rvf-LH. These results tie the subjective

experience of insight to an objective measure—semantic priming—and suggest that people have an

Aha! experience in part because they already had semantic activation that could lead them to recognize

the solution quickly. We believe semantic activation in both hemispheres cooperatively contributes

to problem solving, but weak solution activation that contributes to the Aha! experience is more likely

to occur in the RH than in the LH.

ACTIVATION AND INSIGHT 731

successful solution of insight problems (see, e.g., Schooler

et al., 1993), perhaps because it causes solvers to focus on

their initial representation (Schooler et al., 1995). If difficulty

in solving insight problems stems from failure to recognize

solution-relevant features, the experience of insight might

arise when those features are suddenly recognized—that is,

when activation of such features suddenly surpasses a conscious

threshold.

In Maier’s (1931) classic study, when people solved insight

problems after an indirect hint was provided, solvers

who reported experiencing their solutions as a sudden insight

did not report any awareness of the hint, whereas

solvers who produced their solutions piecemeal uniformly

reported using the hint to reach the solution. Similarly,

when trying to solve anagrams, solvers’ speed, accuracy,

and subjective experience of solution are all affected by

hint words presented too briefly to be identified, but that

apparently elicit some semantic activation (Bowden, 1997).

Furthermore, incorrect solution attempts are often semantically

related to the correct solution (Bowers, Regehr,

Balthazard, & Parker, 1990), suggesting that solutionrelevant

information was influencing solution attempts.

People might have the Aha! experience when they have

solution-relevant activation below the threshold of awareness

prior to producing the solution.

Solvers appear to have solution-related semantic activation

for insight-like problems they have not solved

(Beeman & Bowden, 2000; Bowden & Beeman, 1998).

Problem solvers manifest solution priming for yet-to-besolved

compound remote associate problems (similar to

some items on the remote associates test; Mednick, 1962),

in which solvers must produce a solution word (e.g.,

sweet)

that can form compounds with each of three problem

words (e.g.,

tooth, potato, and heart). After working on

these problems but failing to solve them, solvers read aloud

solution target words faster than unrelated target words

(Beeman & Bowden, 2000; Bowden & Beeman, 1998). A

somewhat similar approach has shown that feeling-ofknowing

for unanswered fact questions is associated with

subsequent solution priming (Yaniv & Meyer, 1987; but

cf. Connor, Balota, & Neely, 1992).

We propose that people have an Aha! experience when

they

suddenly recognize that some information, which

they have already semantically activated, either is the solution

or points to the solution path. The suddenness suggests

that the solution-related activation was previously

below the threshold of awareness, perhaps overshadowed

by other activation not related to the solution. This account

jibes with the consensus view that insight problems

misdirect

solvers to consider unhelpful information or solution

paths: Some misdirected activation may be stronger

than activation of solution-related concepts. Only when

strong misdirected activation subsides can solutionrelated

activation surpass the threshold of consciousness

and be recognized. In contrast, for noninsight problems,

solvers’ strongest initial activation is probably solutionrelated,

and they simply need to carry out operations to

achieve solution (Schooler et al., 1995).

Most previous studies of the insight experience have involved

insight problems typically fitting the criteria outlined

above and fundamentally defined by the fact that

they evoke an Aha! experience. In these studies, it is then

described how solvers subjectively experience such problems

differently than they would noninsight problems

(i.e., problems that do not evoke insight). We used problems

that sometimes evoke insight and sometimes do not.

We then used insight ratings to assess how prior processing

(i.e., semantic activation) differs for problems that

evoke feelings of insight versus those that do not.

Hemispheric Differences

An intriguing question regarding insight solutions is

whether hemispheric differences in patterns of semantic

activation might interact to foster solution. We are not implying

that either hemisphere alone is responsible for solving

insight problems; rather, we propose that the right

hemisphere (RH) engages in cognitive processes that

specifically facilitate solving such problems.

The literature on hemispheric differences in semantic

priming to linguistic stimuli, and the theory that the RH

engages in relatively coarse semantic coding whereas the

left hemisphere (LH) engages in fine semantic coding,

lead us to predict an RH advantage in solution priming for

insight problems. We provide synopses of the theory and

the evidence below; in-depth reviews are available elsewhere

(e.g., Beeman, 1998; Beeman, Bowden, & Gernsbacher,

2000; Beeman & Chiarello, 1998; Beeman et al.,

1994; Burgess & Simpson, 1988; Chiarello, 1998; Chiarello,

Burgess, Richards, & Pollock, 1990; M. Faust & Chiarello,

1998; Koivisto, 1997; Titone, 1998).

According to the RH coarse semantic coding theory,

soon after encountering a word the RH engages in coarse

semantic coding, weakly and diffusely activating alternative

meanings and more distant associates, whereas the

LH engages in relatively fine semantic coding, strongly

focusing activation on a single interpretation of a word and

a few close or contextually appropriate associates (Beeman

et al., 1994; Burgess & Simpson, 1988; Chiarello et al., 1990;

M. Faust & Chiarello, 1998; M. E. Faust & Gernsbacher,

1996; Koivisto, 1997; Nakagawa, 1991; Titone, 1998).

For comprehension of most direct language, LH fine semantic

coding has a clear advantage. For comprehension

of indirect language such as jokes, metaphors, and inferences,

additional semantic coding by the RH may be necessary

(for a review, see Beeman, 1998). This may account

for RH advantages in priming for target words related to

predictive inferences (Beeman et al., 2000) or related to contextually

inappropriate meanings of ambiguous words in

sentences (Titone, 1998). RH coarse semantic coding may

also account for increased neuroimaging signal in the RH

for comprehension of metaphoric sentences over literal

sentences (Bottini et al., 1994), processing of connected

over unconnected discourse (Robertson et al., 2000), and

integration of themes in untitled texts (St. George, Kutas,

Martinez, & Sereno, 1999). Damage to the RH system may

account for the difficulties that RH-damaged patients

732 BOWDEN AND JUNG-BEEMAN

have in understanding jokes (Bihrle, Brownell, Powelson,

& Gardner, 1986; Brownell, Michel, Powelson, & Gardner,

1983), metaphors (Winner & Gardner, 1977), and connotative

meanings (Brownell, Potter, Michelow, & Gardner,

1984), or in drawing inferences (Beeman, 1993; Brownell,

Potter, Bihrle, & Gardner, 1986).

Similarly, solving insight problems often requires secondary

or tertiary interpretations of words and concepts or

information that initially seems only distantly related to

the problem, and might benefit from RH coarse semantic

processing (Beeman & Bowden, 2000; Bowden & Beeman,

1998; Fiore & Schooler, 1998).

In our previous experiments (Beeman & Bowden, 2000;

Bowden & Beeman, 1998), solvers working on compound

remote associate problems revealed different patterns of

semantic activation in the LH and RH. Solvers initially

show solution priming for targets presented to either visual

hemifield, but after they work on the problem for 7 or

15 sec, solution priming is strongly maintained for lvf-RH

target words but fades for rvf-LH target words. Moreover,

when making solution decisions after 7 or 15 sec of solving

effort, solvers respond more quickly to lvf-RH target

words than to rvf-LH target words. This is a striking result,

given the ubiquitous rvf-LH advantage for responding to

words, and suggests that, for insight problems, solutionrelated

activation in the RH is useful at least for recognizing

solutions, and may play a role in generating them.

EXPERIMENT

The following experiment tests for a relation between

solution-related semantic activation, as indexed by priming,

and feelings of insight that accompany solution

recognition. The participants attempted compound remote

associate problems, named solution (or unrelated) words,

made solution decisions, and then rated the insight experience

of their solution recognition. If solvers experience

insight because existing semantic activation is suddenly

recognized as pointing toward the solution, then they

should show greater solution priming on trials for which

they experience insight for their subsequent solution decisions.

Also, as in prior experiments (Beeman & Bowden,

2000; Bowden & Beeman, 1998), solvers should

manifest stronger solution priming and make faster solution

decisions for lvf-RH target words than for rvf-LH target

words.

Method

Participants

 

. Forty-four students (31 women and 13 men) at the

University of Wisconsin at Parkside participated in the experiment

for partial course credit. All the participants were strongly righthanded

according to a brief handedness questionnaire and were native

speakers of American English.

Materials

 

. The problems were 144 compound remote associate

problems (Beeman & Bowden, 2000; Bowden & Beeman, 1998;

Bowden & Jung-Beeman, in press) patterned after some items in the

remote associates test (Mednick, 1962), which have been used to examine

creativity, problem solving, and insight (see Dorfman et al.,

1996). Test problems contained three words, each of which could

form a compound word or phrase with the solution word (e.g.,

palm

 

/shoe/house—TREE). These problems sometimes evoke feelings

of insight and sometimes do not.

Procedure

 

. Trials began with a central fixation cross presented

on a computer screen, followed by three problem words presented simultaneously

in horizontal orientation above, at, and below fixation.

The participants tried to produce the solution within 7 sec; after the

time limit, or sooner if they stated the solution, the problem words

were erased, a tone sounded for 250 msec, and the fixation cross

reappeared for 500 msec (total stimulus onset asynchrony [SOA]

5

7,750 msec). Then, a target word was presented horizontally for

180 msec, with the inner edge 1.5º of visual angle from fixation.

1

The target word was replaced by a letter-fragment pattern mask

that remained on the screen for 120 msec. The participants had 3 sec

from the offset of the mask to name (i.e., read aloud) the target word.

Half of the target words were solution words and half were unrelated

words; half of each of these groups was presented to the left visual

hemifield, and the other half to the right. The unrelated target words

were the solutions to problems 72 trials away (e.g., the Problem 1 occurred

with either its own solution or the solution to Problem 73).

The participants saw each target word only once over the course of

the experiment. Across participants, condition of target words was

rotated so that all target words occurred equally often as both solutions

and unrelated words and in both visual hemifields.

After the participants had named the target word, the experimenter

pressed a key to record whether the response was correct. Immediately

following the experimenter’s response, the word

SOLUTION?

was presented, and the participants indicated whether the target

word was indeed the solution (15 participants responded verbally,

14 responded with a right-hand buttonpress, and 15 responded with

a left-hand buttonpress; there were no effects of response mode). Response

time (RT) from the onset of the event until the participant responded

was recorded. Finally, the word

RATING? was presented with

the rating scale of 1–5 underneath.

2 Ample time and care were taken

to describe appropriate ratings to the participants. Examples of the

Aha! experience were described. Awareness of decision processes

(such as using a strategy) was emphasized as a criterion for lowinsight

ratings, and lack of awareness (“I just knew, I don’t know how

I knew”) was emphasized as the criterion for high-insight ratings.

The ratings were further described roughly along the following lines:

A rating of 1 means that at first, you didn’t know whether the word was

the answer, but after thinking about it strategically (for example, trying

to combine the single word with each of the three problem words) you

figured out that it was the answer. A rating of 3 means that you didn’t

immediately know the word was the answer, but you didn’t have to think

about it much either. A rating of 5 means that when you saw the word

you suddenly knew that it was the answer (“It popped into my head”; “Of

course!” “That’s so obvious”; “It felt like I was already thinking that”).

Ratings of 2 and 4 indicate feelings somewhere in between. It is up to

you to decide what rating to give each of your responses. There are no

right or wrong answers.

Twenty-six participants used the above scale, and 18 used the reverse

scale; there were no effects of scale direction. The participants

were tested individually, with their chins positioned in a chinrest so

that their heads were held steady and at a constant distance from the

computer monitor. They were given five practice problems with target

words.

Results

On average, the participants solved 19.4% (

SD 5 6.0)

of the problems within the 7-sec time limit and correctly

named 90.2% (

SD 5 6.8) of the brief, lateralized target

words. The data from 6 participants were replaced: 4 solved

few problems (

.2.5 SDs below the mean—i.e., fewer than

4.75%), 1 had few response latencies recorded (

.2.5 SDs

ACTIVATION AND INSIGHT 733

below the mean—i.e., RTs recorded on fewer than 73% of

the trials), and 1 showed very slow naming latencies and

hyperpriming (

.300 msec of priming, .2.5 SDs above

the mean), suggesting strategic naming. The main effects

and effects replicating earlier results are discussed after

the novel analysis of insight rating data.

Insight ratings and the relation to solution priming

 

.

The main focus of this experiment was to determine

whether the participants’ feelings of insight, as indexed by

the rating scale, had to do with solution-related activation,

as indexed by solution priming (naming solutions faster

than naming unrelated target words) for problems they

had not yet solved. All trials on which the problem was

solved during the 7-sec time limit were excluded from the

analysis.

3 We examined the relation between insight ratings

that the participants gave for their correct solution decisions

(i.e., hits) and the solution priming manifest when

they named targets on those trials. Only ratings by hemifield

cells for which a participant had two or more valid latencies

were considered. Data from 2 additional participants

were removed because they had fewer than five hits,

and data from 2 others were removed because they assigned

a single rating to nearly all the trials. Figure 1 shows

solution priming in each hemisphere for trials assigned

each insight rating by the remaining 40 participants.

To compare the insight-priming relation across hemispheres,

a Pearson correlation between insight rating

scores and priming

4 was calculated for each hemifield for

each participant. This gave a measure, for each participant,

of whether his or her priming scores in each hemifield

were related to his or her idiosyncratic use of the rating

scale. Correlations were predicted to be low, because

there were few observations per hemifield

3 rating condition

cell and because semantic activation is just one

component contributing to both the RT and the insight rating;

moreover, semantic activation in either hemisphere

could presumably affect insight ratings, whereas priming

was assessed in only one hemifield on each trial. These

correlation coefficients were then

z9-transformed (Cohen

& Cohen, 1983). A positive correlation would reveal that

the participants showed more priming for solution words

that subsequently elicited a feeling of insight for their solution

decisions. The participants’

z9-transformed correlation

coefficients were entered into a

t test, which revealed

that, on average, the participants’ insight ratings

correlated better with solution priming for lvf-RH targets

(average

z95.178, SE50.040) than for rvf-LH targets [average

z

 

9 5 .048, SE 50.041, t(39) 5 2.3, p , .03].

Because only 8 participants used every insight rating

often enough to have more than two observations per

hemifield

3 rating condition cell, an overall analysis of

variance (ANOVA) was untenable. Given the reliable

hemispheric difference in priming–insight correlations

and a priori hypotheses, paired

t tests were used to compare

rvf-LH and lvf-RH priming at each rating level (for

participants who had data in both cells, leaving

ns of 11,

23, 37, 37, and 27 for ratings of 1, 2, 3, 4, and 5, respectively).

These contrasts revealed a reliable lvf-RH advantage

in solution priming only on trials for which the participants

rated their solution decisions as most insightful

[rating of 5: 40-msec lvf-RH advantage,

t(26) 5 5.2, p 5

.03; rating of 4: 63-msec lvf-RH advantage,

t(36) 5 3.6,

p

 

, .07; at all other ratings, ts , 1].

Data Replicating Results

of Previous Experiments

Naming latency

 

. When the participants failed to solve

problems within 7 sec, they named target words presented

to the rvf-LH 21 msec more quickly than target words presented

to the lvf-RH [

F(1,43)5 4.0, p5.05]. See Table 1

for mean naming latencies of the 44 participants. The participants

also showed priming, naming solution target

words 55 msec more quickly than they named unrelated

target words [

F(1,43) 5 45.9, p , .0001]. The participants

showed reliable priming (70 msec) for lvf-RH solution

words [

F(1,43) 5 48.4, p , .0001] and for rvf-LH

solution words [39 msec;

F(1,43)5 11.1, p, .002]. Most

importantly, a reliable target type

3 hemifield3 relatedness

interaction reflected a 33-msec RH advantage in solution

priming [

F(1,43) 5 4.4, p 5 .04].

When the participants solved problems, they named

rvf-LH target words 44 msec more quickly than lvf-RH

Figure 1. Mean priming (naming latency for solution words minus latency for unrelated words, in msec)

by insight rating and hemifield of target word.

734 BOWDEN AND JUNG-BEEMAN

target words [

F(1,43)5 9.8, p , .005; see Table 1]. They

also showed priming, naming solution target words 79msec

more quickly than they named unrelated target words

[

F(1,43)5 18.6, p , .0001]. The participants showed reliable

solution priming (106 msec) for lvf-RH target

words [

F(1,43) 5 19.0, p , .0001] and for rvf-LH target

words [48 msec;

F(1,43)5 5.1, p , .03]. A target type3

hemifield of presentation

3 relatedness interaction reflected

a 66-msec priming RH advantage for solution

priming [

F(1,43) 5 4.7, p , .04].

Solution decision latency

 

. We examined solution decision

latencies only for trials on which the participants

had already correctly named the target words, and only

following unsolved problems. See Table 2 for mean decision

latencies from 42 participants (data from the 2 participants

with fewer than five hits were removed, as has

been noted above). There was a main effect of response

type: The participants made hit responses (responding

“yes” when the target word was the solution) 245msec more

quickly than they made correct rejections [responding

“no” when the target word was not the solution;

F(1,43),

5.7,

p , .03]. The participants responded 67 msec more

quickly to words presented to the lvf-RH than they did to

words presented to the rvf-LH [

F(1,43)5 2.1 , .16]. Response

type and hemifield of presentation did not interact

[

F(1,43) , 1]. The RH advantage in solution decision latencies,

reliable in previous experiments, was not reliable

here, perhaps because decisions were delayed until after

solvers named the target words and the experimenter

scored their responses.

Solution decision accuracy

 

. When the participants

correctly named the target words following unsolved

problems, they made subsequent solution decisions as accurately

for lvf-RH targets (85.8%) as for rvf-LH targets

(86.4%;

t, 1; see Table 2). Moreover, a sensitivity analysis

(

d9) revealed that the participants were equally sensitive

for their solution decisions on lvf-RH target words

(

d9 5 2.32, SD 5 .84), and on rvf-LH target words (d9 5

2.37,

SD 5 .81, t , 1). In prior studies (Beeman & Bowden,

2000; Bowden & Beeman, 1998), there was a slight

rvf-LH advantage in decision accuracy. Because the participants

did not first name the target words, those earlier

decision data likely included more lvf-RH trials than rvf-

LH trials on which the participants failed to identify the

target words, given that people typically are better able to

read words presented to the rvf-LH than words presented

to the lvf-RH.

DISCUSSION

After attempting to solve compound remote associate

problems for 7 sec, the participants rated their solution decisions

as more insightful when they had prior semantic

activation of the solution, as indexed by solution priming.

Interestingly, this association between feelings of insight

and solution activation was stronger in the RH than in the

LH. Across insight ratings, the participants showed more

solution priming for lvf-RH than for rvf-LH target words

and made solution decisions more quickly for lvf-RH than

for rvf-LH target words, replicating earlier results (Beeman

& Bowden, 2000; Bowden & Beeman, 1998). In addition,

the current results showed that, on trials in which the

target word was identified, the participants made solution

decisions in the lvf-RH just as accurately as they did in

the rvf-LH.

The current paradigm differs from others employed to

study the subjective experience of insight (Davidson, 1995;

Metcalfe, 1986a, 1986b; Metcalfe & Wiebe, 1987) in a

number of ways. Most importantly, this experiment used

individual ratings of insight experience on a trial-by-trial

basis. This is possible with compound remote associate

problems, which sometimes evoke feelings of insight and

Table 1

Mean Naming Latencies (in Milliseconds) and Standard Errors (

SEs)

Following Solved and Unsolved Problems

Solved Unsolved

rvf-LH lvf-RH rvf-LH lvf-RH

Target Type Mean

SE Mean SE Mean SE Mean SE

Unrelated 730 20 803 27 784 25 821 27

Solution 682 25 697 30 745 21 751 24

Priming 48 106 39 70

Table 2

Mean Solution Decision Latency (and Standard Errors,

SEs) (in Milliseconds) After Naming Target Word

and Accuracy Following Unsolved Problems

rvf-LH lvf-RH

Correct False Correct False

Rejections Alarm Hit Miss Rejections Alarm Hit Miss

Dependent Variable

M SE M SE M SE M SE M SE M SE M SE M SE

Latency 2,152 150 2,778 246 1,942 119 2,630 181 2,114 135 2,907 239 1,833 113 2,821 198

Accuracy (%) 92.3 1.5 80.8 1.5 90.3 1.4 82.0 2.1

ACTIVATION AND INSIGHT 735

sometimes do not. Most importantly, even if the subjective

ratings system employed here is flawed, “soft,” and possibly

inconsistent across participants, these results link the

subjective ratings to an independent measure (priming) of

cognitive processing (semantic activation).

The fact that solvers had insight-like experiences on the

same trials for which they manifested solution priming

supports the position that the Aha! experience reflects, in

part, prior subthreshold activation related to the solution.

That is, solvers feel the Aha! experience of insight when

they suddenly recognize that an already activated concept

is the solution or, in more complex problems, points to the

solution path. For some insight problems, solvers easily

achieve solution once they recognize the solution path; for

other problems, further noninsight processing is necessary

after the critical insight (Dominowski & Dallob, 1995;

Schooler et al., 1995).

In our experiment, the fact that solvers manifest priming

indicates that they had solution-related activation; the

fact that they had not solved the problem indicates that

such activation was below the threshold of awareness.

When the participants saw the solution word, it was immediately

recognized as the solution, leading to an Aha!

experience. Note that the solution priming was measured

when solvers named the solution words (a measure of lexical

activation, although expectancies can also play a role

at this long SOA; see Neely, 1991), so it is not the case

that the insight ratings merely reflected quick solution decisions;

rather, they were associated with an independent

measure of semantic activation for that solution, prior to

solution decision. Solution-related activation previously

below the threshold of awareness could surpass that

threshold, because strong misdirected activation (perhaps

in the LH) may subside. Alternatively, solvers could increase

solution-related activation because they may reinterpret

a problem word or encounter hints or environmental

cues (see, e.g., Bowden, 1997; Maier, 1931).

The results also indicate that subthreshold solution activation

more often occurs in the RH than in the LH, and

that such RH activation is more strongly associated with

the Aha! experience than is LH semantic activation. There

are a few possible interpretations of this hemispheric difference

in the priming–insight association. First, it is possible

that subthreshold solution activation in the LH simply

does not generate a feeling of insight when solvers

achieve or recognize solutions. Second, it is possible that

subthreshold solution activation in either hemisphere can

create a feeling of insight, but that such activation is more

likely to occur in the RH than in the LH. The observed

lack of association between LH solution priming and insight

ratings in this case is probabilistic: In our study, insight

ratings reflected activation in either hemisphere, but

hemifield priming assessed activation primarily in one

hemisphere. If solution activation occurred more frequently

in the RH, as the RH advantage in solution priming

suggests, then on some trials the participants would

experience insight due to RH solution activation but not

show priming for rvf-LH solution targets.

It is hypothetically possible that participants may consciously

generate the solution in either hemisphere (although

we maintain that both hemispheres normally contribute

to solution generation) and take longer to verify

solutions generated by the RH than by the LH. If so, RHgenerated

solutions have a longer window of time during

which participants are aware of the solution prior to responding.

If the solution appears as a target word during

this window, participants may provide a high insight rating

because they were “already thinking that,” partially

fulfilling one of several criteria for assigning an insight

rating. However, it should be noted that the insight ratings

stressed many features of the Aha! experience, and the

general tone implied a lack of awareness prior to the instant

of recognition. Furthermore, we maintain that once

solution activation rises to the point that solvers are aware

of and/or attempting to verify solution candidates, this activation

spreads to both hemispheres.

Thus, we conclude that the RH advantages in solution

priming,

5 solution decision latency, and priming–insight

association all suggest that the RH plays a special role in

solving insight problems and in feelings of insight. These

results are consistent with the fact that hints to insight problems

are more effective when presented to the lvf-RH than

when presented to the rvf-LH (Fiore & Schooler, 1998).

Both the size and the strength of activated semantic

fields may contribute to these phenomena. Large semantic

fields activated by RH coarse semantic coding seem

better able to detect semantic overlap, as has been discussed

elsewhere (for a review, see Beeman, 1998). For instance,

semantic activation in the RH is more sensitive than semantic

activation in the LH to potential connective inferences

(Beeman et al., 2000) and to multiple weakly related

primes (Beeman et al., 1994). For compound remote associate

problems, the LH may activate the solution in connection

with only one problem word and fail to detect the

semantic overlap necessary to achieve solution. Then, this

nonconverging activation decays in the LH, perhaps being

out-competed by misdirected activation, whereas converging

activation in the RH is maintained for a longer

time (Beeman & Bowden, 2000).

Solution-related activation in the RH may easily remain

subthreshold, because large, diffusely activated semantic

fields poorly support selection into awareness. In contrast,

solution-related activation in the LH is likely to exceed

threshold and reach awareness (a process we roughly refer

to as

selection), perhaps with a boost from attention. According

to our theory, this tendency emerges due to small

but strongly activated semantic fields arising from LH

fine semantic coding. The LH could be as adept as the RH

at activating solution-related information, but LH activation

leads to immediate solution, whereas RH activation

does not. Indeed, selecting a solution concept seems quite

important in discovering insight solutions (Davidson,

1995), suggesting that the LH may be necessary for solution

generation. However, in all five of our experiments in

which the participants had 7 or 15 sec to solve compound

remote associate problems, the participants demonstrated

736 BOWDEN AND JUNG-BEEMAN

a reliable (or nearly reliable) RH advantage in solution

priming or in raw solution decision latency after generating

solutions (Beeman & Bowden, 2000; Bowden & Beeman,

1998; present experiment).

We are not arguing that the LH solves noninsight problems

and the RH solves insight problems, or that the LH

is conscious and the RH unconscious. Rather, we argue

that people make conscious decisions influenced by partially

independent activation in each hemisphere. We posit

that action and awareness are supported by population

coding—that is, the summed distributed activity of many

thousands of neurons, without the need of an executive, homunculus,

or grandmother cell. This population is divided

over both hemispheres, and is therefore the sum of two

processing styles arising, perhaps, from slightly asymmetric

neural substrates: relatively fine semantic coding in the

LH and relatively coarse semantic coding in the RH. If the

LH strongly activates a narrow field of information, most

of which will also be weakly activated in the RH, the information

activated in the LH will tend to dominate the

population code underlying selection of information for

consciousness and responses. Contributions from the RH

seem particularly important when people comprehend

discourse in which initially unimportant information becomes

important, such as when they draw some inferences

or understand jokes (for a review, see Beeman, 1998). Because

information can be shared between the hemispheres,

these complementary processes are not strictly isolated

from each other. However, analyzing humans’ integrated

awareness and action into hemispheric components can illuminate

the critical processes and factors of complex behaviors

such as problem solving.

REFERENCES

Beeman, M.

(1993). Semantic processing in the right hemisphere may

contribute to drawing inferences from discourse.

Brain & Language,

44

 

, 80-120.

Beeman, M.

(1998). Coarse semantic coding and discourse comprehension.

In M. Beeman & C. Chiarello (Eds.),

Right hemisphere language

comprehension: Perspectives from cognitive neuroscience

 

Beeman, M. J., & Bowden, E. M.

(2000). The right hemisphere maintains

solution-related activation for yet-to-be-solved insight problems.

Memory & Cognition

 

, 28, 1231-1241.

Beeman, M. J., Bowden, E.M., & Gernsbacher, M. A.

(2000). Right

and left hemisphere cooperation for drawing predictive and coherence

inferences during normal story comprehension.

Brain & Language,

71

 

, 310-336.

Beeman, M., & Chiarello, C.

(1998). Right hemisphere language

comprehension: Perspectives from cognitive neuroscience

 

Beeman, M., Friedman, R. B., Grafman, J., Perez, E., Diamond, S.,

& Lindsay, M. B.

(1994). Summation priming and coarse semantic

coding in the right hemisphere.

Journal of Cognitive Neuroscience, 6,

26-45.

Bihrle, A. M., Brownell, H. H., Powelson, J. A., & Gardner, H.

(1986). Comprehension of humorous and non-humorous materials by

left and right brain-damaged patients.

Brain & Cognition, 5, 399-411.

Bottini, G., Corcoran, R., Sterzi, R., Paulescu, E., Schenone, P.,

Scarpa, P., Frackowiak, R. S. J., & Frith, C. D.

(1994). The role of

the right hemisphere in the interpretation of figurative aspects of language:

A positron emission tomography activation study.

Brain, 117,

1241-1253.

Bowden, E. M.

(1997). The effect of reportable and unreportable hints

on anagram solution and the Aha! experience.

Consciousness & Cognition,

6

 

, 545-573.

Bowden, E.M., & Beeman, M. J.

(1998). Getting the right idea: Semantic

activation in the right hemisphere may help solve insight problems.

Psychological Science

 

, 9, 435-440.

Bowden, E. M., & Jung-Beeman, M.

(in press). Compound remote associate

problems.

Behavior Research Methods, Instruments, & Computers.

Bowers, K. S., Regehr, G., Balthazard, C., & Parker, K.

(1990). Intuition

in the context of discovery.

Cognitive Psychology, 22, 72-110.

Brownell, H.H., Michel, D., Powelson, J.A., & Gardner, H.

(1983).

Surprise but not coherence: Sensitivity to verbal humor in right hemisphere

patients.

Brain & Language, 18, 20-27.

Brownell, H. H., Potter, H. H., Bihrle, A. M., & Gardner, H.

(1986). Inference deficits in right brain-damaged patients.

Brain &

Language

 

Brownell, H.H., Potter, H.H., Michelow, D., & Gardner, H.

(1984).

Sensitivity to lexical denotation and connotation in brain-damaged patients:

A double dissociation?

Brain & Language, 22, 310-321.

Burgess, C., & Simpson, G.

(1988). Hemispheric processing of ambiguous

words.

Brain & Language, 33, 86-104.

Chiarello, C.

(1998). On codes of meaning and the meaning of codes:

Semantic access and retrieval within and between hemispheres. In

M. Beeman & C. Chiarello (Eds.),

Right hemisphere language comprehension:

Perspectives from cognitive neuroscience

 

Chiarello, C., Burgess, C., Richards, L., & Pollock, A.

(1990). Semantic

and associative priming in the cerebral hemispheres: Some

words do, some words don’t, . . . sometimes, some places.

Brain & Language,

38

 

, 75-104.

Cohen, J., & Cohen, P.

(1983). Applied multiple regression/correlation

analysis for the behavioral sciences

 

Connor, L. T., Balota, D. A., & Neely, J. H.

(1992). On the relation

between feeling of knowing and lexical decision: Persistent subthreshold

activation or topic familiarity?

Journal of Experimental Psychology:

Learning, Memory, & Cognition

 

Davidson, J. E.

(1995). The suddenness of insight. In R. J. Sternberg &

J. E. Davidson (Eds.),

The nature of insight (pp. 125-156). Cambridge,

MA: MIT Press.

Dominowski, R. L., & Dallob, P. I.

(1995). Insight and problem solving.

In R. J. Sternberg & J. E. Davidson (Eds.),

The nature of insight

(pp. 33-62). Cambridge, MA: MIT Press.

Dorfman, J., Shames, V. A., & Kilhstrom, J. F.

(1996). Intuition, incubation,

and insight: Implicit cognition in problem solving. In G. Underwood

(Ed.),

Implicit cognition (pp. 257-296). Oxford: Oxford University

Press.

Faust, M., & Chiarello, C.

(1998). Sentence context and lexical ambiguity

resolution by the two hemispheres.

Neuropsychologia, 36, 827-

836.

Faust, M., Kravetz, S., & Babkoff, H.

(1993a). Hemisphericity and

top-down processing of language.

Brain & Language, 44, 1-18.

Faust, M., Kravetz, S., & Babkoff, H.

(1993b). Hemispheric specialization

or reading habits: Evidence from lexical decision research with

Hebrew words and sentences.

Brain & Language, 44, 254-263.

Faust, M. E., & Gernsbacher, M.A.

(1996). Cerebral mechanisms for

suppression of inappropriate information during sentence comprehension.

Brain & Language

 

, 53, 234-259.

Fiore, S. M., & Schooler, J. W.

(1998). Right hemisphere contributions

to creative problem solving: Converging evidence for divergent

thinking. In M. Beeman & C. Chiarello (Eds.),

Right hemisphere language

comprehension: Perspectives from cognitive neuroscience

(pp. 349-371). Mahwah, NJ: Erlbaum.

Gick, M. L., & Lockhart, R. S.

(1995). Cognitive and affective components

of insight. In R. J. Sternberg & J. E. Davidson (Eds.),

The nature

of insight

 

Koivisto, M.

(1997). Time course of semantic activation in the cerebral

hemispheres.

Neuropsychologia, 35, 497-504.

Maier, N.R. F.

(1931). Reasoning in humans II: The solution of a problem

and its appearance in consciousness.

Journal of Comparative Psychology,

12

 

, 181-194.

Mednick, S. A.

(1962). The associative basis of the creative process.

Psychological Review

 

, 69, 220-232.

ACTIVATION AND INSIGHT 737

Metcalfe, J.

(1986a). Feeling of knowing in memory and problem solving.

Journal of Experimental Psychology: Learning, Memory, & Cognition

 

,

12

 

, 288-294.

Metcalfe, J.

(1986b). Premonitions of insight predict impending error.

Journal of Experimental Psychology: Learning, Memory, & Cognition

 

,

12

 

, 623-634.

Metcalfe, J. & Wiebe, D.

(1987). Intuition in insight and noninsight

problem solving.

Memory & Cognition, 15, 238-246.

Nakagawa, A.

(1991). Role of anterior and posterior attention networks

in hemispheric asymmetries during lexical decisions.

Journal of Cognitive

Neuroscience

 

Neely, J. H.

(1991). Semantic priming effects in visual word recognition:

A selective review of current findings and theories. In D. Besner

& J. W. Humphreys (Eds.),

Basic processes in reading: Visual word

recognition

 

Ohlsson, S.

(1992). Information-processing explanations of insight and

related phenomena. In M. Keane & K. Gilhooley (Eds.),

Advances in

the psychology of thinking (

 

Robertson, D.A., Gernsbacher, M.A., Guidotti, S. J., Robertson,

R.R.W., Irwin, W., Mock, B. J., & Campana, M.E.

(2000). Functional

neuroanatomy of the cognitive process of mapping during discourse

comprehension.

Psychological Science, 11, 255-260.

Schooler, J. W., Fallshore, M., & Fiore, S. M.

(1995). Epilogue:

Putting insight into perspective. In R. J. Sternberg & J. E. Davidson

(Eds.),

The nature of insight(pp.559-587). Cambridge, MA: MIT Press.

Schooler, J.W., & Melcher, J. (

1995). The ineffability of insight. In

S. M. Smith & T. B. Ward (Eds.),

The creative cognition approach

(pp. 97-133). Cambridge, MA: MIT Press.

Schooler, J.W., Ohlsson, S., & Brooks, K.

(1993). Thoughts beyond

words: When language overshadows insight.

Journal of Experimental

Psychology: General

 

Seifert, C. M., Meyer, D. E., Davidson, N., Patalano, A. L., &

Yaniv, I.

(1995). Demystification of cognitive insight: Opportunistic

assimilation and the prepared-mind perspective. In R. J. Sternberg &

J. E. Davidson (Eds.),

The nature of insight (pp. 65-124). Cambridge,

MA: MIT Press.

Smith, S. M.

(1995). Getting into and out of mental ruts: A theory of

fixation, incubation, and insight. In R. J. Sternberg & J. E. Davidson

(Eds.),

The nature of insight (pp. 229-252). Cambridge, MA: MIT

Press.

St. George, M. Kutas, M., Martinez, A., & Sereno, M. I.

(1999).

Semantic integration in reading: Engagement of the right hemisphere

during discourse processing.

Brain, 122, 1317-1325.

Titone, D.

(1998). Hemispheric differences in context sensitivity during

lexical ambiguity resolution.

Brain & Language, 65, 361-394.

Winner, E., & Gardner, H.

(1977). The comprehension of metaphor

in brain-damaged patients.

Brain, 100, 719-727.

Yaniv, I., & Meyer, D. E.

(1987). Activation and metacognition of inaccessible

stored information: Potential bases for incubation effects in

problem solving.

Journal of Experimental Psychology: Learning,

Memory, & Cognition

 

NOTES

1. Hemifield effects with Hebrew stimuli demonstrate that direction

of reading affects neither the basic rvf-LH advantage in reading words

(M. Faust, Kravetz, & Babkoff, 1993b) nor the patterns of semantic

priming across the hemifields/hemispheres (M. Faust, Kravetz, &

Babkoff, 1993a).

2. The rating scale appeared on all trials regardless of whether the participants

indicated that the target word was the solution or was not the solution.

This was done so that the appearance of the rating scale did not

give the participants feedback about the accuracy of their solution decisions.

Only ratings and data from trials on which the participants made

hits (correctly accepting solutions) after failing to solve the problems

were analyzed.

3. It is possible that some participants solved the problem in the interval

between the offset of the problem triad and the onset of the target

word. However, on average, the participants solved 2.1 problems in the

final 750 msec of the 7-sec time limit. Only half of these (i.e., 1 problem)

should be followed by a solution target, and this could not have a

great influence on the average RT. Moreover, such solutions should

occur with equal frequency prior to lvf-RH and rvf-LH target words, and

so cannot explain differential priming in the hemifields.

4. Priming scores at all rating points were derived using the common

baseline of latencies for

all unrelated words within each hemifield, because

insight ratings for unrelated words would not be meaningful.

5. A “ceiling effect” is unlikely to be limiting priming for rvf-LH targets,

given that (1) the participants responded equally fast to solution

words presented in both hemifields, (2) naming times were relatively slow

in comparison with single-word priming paradigms, and (3) rvf-LH advantages

in priming have been documented with other prime types.

(Manuscript received May 2, 2000;

revision accepted for publication July 10, 2002.)