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Unconscious thinking theory

Author: Dr Simon Moss


Unconscious thought theory, outlined by Dijksterhuis and Nordgren (2006), characterizes the contexts in which individuals should rely on their intuition, at least after some delay, rather than consider issues and decisions carefully and systematically. In particular, Dijksterhuis and colleagues differentiated two approaches that can be applied to reach decisions and to uncover creative suggestions. First, individuals can reflect upon the issue consciously, deliberately, methodically, logically, and analytically. They could, for example, compare two job applicants on various attributes in sequence--such as experience, qualifications, knowledge, skill, interest, experience, and style--ascertaining which of the individuals demonstrates the most number of strengths. Second, individuals can utilize their intuitive preferences, which seem to emanate from a set of unconscious processes. They might, for instance, consider the applicants briefly, distract themselves for a while, and then trust their instinctive reactions (for a related distinction, see Cognitive experiential theory).

Benefits of conscious thinking

According to this theory, conscious thinking is superior to unconscious thinking in some circumstance, but inferior in other contexts. In particular, conscious thinking is superior when individuals need to generate precise responses, such as an answer to the question what is 5 x 8.2. A conscious, analytical process is likely to derive the answer of 41. In contrast, an unconscious, intuitive process is likely to generate a more approximate answer, such as 50.

Because conscious thinking can generate more precise estimates, this approach is also more effective when individuals need to decide between alternatives that vary on two or three attributes only. For example, Dijksterhuis, Bos, Nordgren, and Van Baaren (2007) showed that individuals are more inclined to choose the appropriate towel or oven mitt--products that vary on a few characteristics only--when they considered their purchase consciously and methodically rather than intuitively.

Benefits of unconscious thinking

When the alternatives vary on many attributes, or the implications of these qualities are unclear or unpredictable, such as when individuals need to decide which house or car to purchase, unconscious thinking ensures better decisions than does conscious thinking (Dijksterhuis, Bos, Nordgren, & Van Baaren, 2007). In contrast to conscious thinking, in which only a circumscribed set of factors can be considered at a time, unconscious thinking is able to incorporate, weight, and integrate unlimited information to optimize decisions.

Dijksterhuis (2004) showed that unconscious thoughts somehow organize information more effectively than conscious thinking. For example, in one study, Dijksterhuis presented 18 descriptions of one person: six of these descriptions related to the intelligence of this person, another six of these descriptions related to the extraversion of this individual, and finally six of these descriptions related to political orientation. Participants who had been asked to think unconsciously, rather than consciously, recalled more of these descriptions. Specifically, consecutive recollections tended to pertain to the same attribute: intelligence, extraversion, or political orientation. This observation reveals that unconscious thinking somehow organizes information into distinct clusters.

Similarly, Bowers, Regehr, Balthazard, and Parker (1990) developed a model that characterizes the potential operations that underpin intuition--and thus, arguably, unconscious thinking. Intuition entails two distinct phases. The first phase is called guiding. During this phase, an immediate problem activates a network of memories. Memories that are related to the problem as well as to each other become increasingly more salient. Hence, a coherent set of relevant memories or constructs are activated. The second phase is called the integrative stage. When a specific set of memories, which combine to represent a hypothesis, exceed some threshold level of activation, individuals experience a sense of insight or discovery.

Memory of benefits

Furthermore, unconscious thoughts bias memories as well to amplify the benefits and merits of the preferred option. For example, in another study, Dijksterhuis (2004) presented information about several potential roommates. Each roommate seemed to demonstrate both desirable and undesirable qualities. However, after participants decided which of these options they prefer, they tended to remember the desirable qualities of the chosen roommate and the undesirable qualities of the rejected roommates. As a consequence, after some delay, unconscious thoughts will generate a distinct and unambiguous intuition that indicates which alternative seems most appropriate.

Conscious thoughts often bias memories as well. However, these conscious thoughts, such as identifying reasons and justifications, bias memory and attention to salient rather than important information (Wilson, Hodges, & LaFleur, 1995). Key attributes and factors are often disregarded.


Apart from optimizing complex decisions, unconscious thinking also facilitates a form of creativity, called divergent thinking. To illustrate, in a study conducted by Dijksterhuis and Meurs (2006), participants were asked to propose a series of possible labels for novel shapes of pasta. Three examples were presented, each of which ended with the letter i. If individuals engaged in conscious, deliberate thinking before attempting to identify solutions, their suggestions also ended in this letter. That is, conscious thinking applies specific rules or principles and thus generates solutions that do not diverge from the underlying pattern. In contrast, when individuals engaged in unconscious thinking before attempting to identify solutions--that is, by engaging in some other activity--their suggestions were less likely to end in this letter.

Futhermore, unconscious thinking is more likely to uncover remote associations between concepts. To illustrate, in one of the studies conducted by Zhong, Dijksterhuis, and Galinsky (2008), participants had to identify one word, such as field, that is related to three other terms, such as trip, house, and goal.

When the task was especially difficult--and the associations were thus remote--unconscious thinking did increase the accessibility of words that represent the correct answers. That is, after completing this task, strings of letters, such as falc, appeared on a screen. Participants had to determine whether or not the strings were words. If participants had engaged in unconscious thinking, they could more rapidly recognize words that correspond to the previous answers (Zhong, Dijksterhuis, & Galinsky, 2008). However, when the task was moderately difficult, unconscious thinking did not increase the accessibility of words that represent the correct answers.

Consistent judgments

When individuals invoke unconscious thinking, in lieu of careful deliberation, their judgments tend to be more consistent over time. Specifically, when individuals deliberate systematically to decide which alternative to choose, they tend to orient their attention to only a subset of attributes. When they need to decide which painting to choose, for example, they might direct their attention to the color rather than perhaps the price, size, originality, and so forth. They might disregard features that are important but subtle or common.

When they reflect upon the alternatives later, their preferences might change. They might direct their attention to attributes they neglected during their previous reflections. This possibility was demonstrated by Levine, Halberstadt, and Goldstone (1996). In their study, participants evaluated a series of faces, all of which varied on six features, such as the shape of their nose. Only half of the participants were asked to reflect upon the reasons to justify their evaluations.

Levine, Halberstadt, and Goldstone (1996) subjected these evaluations to multidimensional scaling. This approach revealed that participants who reflected upon the reasons-and thus deliberated over their evaluations-did not consistently focus on the same features across the faces. When individuals deliberate over their judgments, the key attributes seem to vary over time.

Accordingly, unconscious thinking should generate more consistent judgments. Nordgren and Dijksterhuis (2009) substantiated this proposition. In one study, for example, participants evaluated a series of Chinese ideograms. Later, they evaluated an overlapping set of ideograms as well. Some of the participants were instructed to deliberate carefully, striving to generate reasons to justify their evaluations. Other participants were encouraged to trust their intuition, which represents unconscious thinking.

When deliberation rather than intuition was encouraged, evaluations of the same ideograms varied appreciably over time. The same pattern was observed when individuals evaluated paintings, flavors of jelly beans, and apartments. Furthermore, this effect of deliberation on inconsistency was especially pronounced when the alternatives differed on many, rather than few, attributes.

The proposition that deliberation can translate into inconsistency could, according to Nordgren and Dijksterhuis (2009), aligns with the impact bias. That is, individuals often overestimate the emotional consequences of positive or negative events. When individuals deliberate, they might initially orient their attention to only the salient, emotional facets of some event.

Lee, Amir, and Ariely (2009) also confirmed that cognitive deliberation can undermine consistency in preferences. To estimate consistency, in this study, participants were exposed to a series of products, such as a voice recording pen, an FM pen, and a photo album of audio and visual pictures, together with a description of each item as well as a photograph and label. A pair of products was then presented, and participants specified the item they preferred. This process was repeated for every possible pair. Participants were designated as inconsistent, for example, if they often rated one item as better than a second item, the second item as better than a third item, but the third item as better than the first item.

Across a series of studies, Lee, Amir, and Ariely (2009) showed that participants were more likely to demonstrate inconsistency if they applied cognitive processes, analogous to deliberation, rather than emotional processes, analogous to unconscious thinking. For example, inconsistency was pronounced when labels, rather than pictures, were presented while participants evaluated their preferences. Presumably, the labels, which represent symbolic codes, elicited cognitive deliberation (cf Epstein 2003).

In subsequent studies, Lee, Amir, and Ariely (2009) demonstrated that black and white rather than color photographs also compromised consistency. Presumably, the color photographs are more vivid, which facilitates emotional processing (Loewenstein, 1996). Similarly, after participants reflected upon two occasions in which they trusted their feelings, their preferences were more consistent. After they attempted to reflect upon ten occasions in which they trusted their feelings--a difficult task, which might challenge this trust in feelings and encourage cognitive deliberation--preferences were less consistent. Finally, when individuals were asked to memorize a very long sequence of digits, which should stifle cognitive deliberation, consistency increased.

One of the implications of this finding is that market researchers, to understand customers, should attempt to cub deliberation. They should present vivid photographs, for example, and ask individuals what they feel rather than think.

Processing style

As Dijkstra, van der Pligt, van Kleef, and Kerstholt (2012) showed, conscious deliberation, in contrast to unconscious thinking, will tend to confine attention to specific details. In contrast, unconscious thinking increases the likelihood that attention is distributed across a broader array of features or considerations. This focus of attention may explain some of the benefits of unconscious thinking over conscious deliberation.

Dijkstra, van der Pligt, van Kleef, and Kerstholt (2012) conducted a series of studies to validate this argument. The first study was designed to replicate the benefits of unconscious thinking in a particular setting: the evaluation of art. Participants were exposed to eight modern paintings. Four of these paintings had been touted as high in quality by art experts. The other four paintings, which appeared in the museum of bad art, had been touted as low in quality by art experts. Participants rated each piece on a 100 point scale, from very good to very bad. Some of the individuals were encouraged to utilize their intuition. Other individuals were encouraged to deliberate carefully and consider different facets or features of the paintings separately. In contrast to participants who deliberated carefully, participants who utilized their intuition rated the paintings more accurately. That is, they were more likely to rate all the high quality paintings more favorably than all the low quality paintings.

In the second study, participants first completed a measure that ascertains whether they tend to orient their attention to overarching patterns or specific details. Specifically, on each trial, a shape was presented. The shape was always a large letter, such as an H, composed of smaller letters, such as Fs. On each trial, they needed to decide whether an H or L appeared. Next, they rated the eight paintings.

Some participants responded more rapidly to the letters whenever the larger letter was the target. These participants, who presumably orient their attention to overarching patterns, tended to rate the paintings accurately. In contrast, some participants responded more rapidly whenever the smaller letters were the target. These participants, who presumably orient their attention to specific details, tended to rate the paintings inaccurately. Therefore, if people are sensitive to overarching patterns, they tend to rate paintings accurately.

Indeed, a third study showed that procedures that prime an orientation to global patterns also enhanced the accurate of ratings. Furthermore, the final study showed that processing style-that is, an orientation to global patterns instead of specific details-mediated the association between intuition and accurate ratings. In addition, this study explored ratings of poetry instead of paintings. Overall, these studies indicate that conscious deliberation may confine attention to only a subset of features and details, increasing the possibility that individuals may overlook the overarching pattern.

Integration of direct observations and indirect information

When individuals need to reach decisions, they often need to integrate two distinct forms of information. Some of the information may have been extracted from personal observations, called direct information. In a court case, for example, jurors may be permitted to observe a victim or scan a photograph of this person. Other information may be extracted from the testimonies of other people, called indirect information. Jurors, for example, may hear depictions of the victim, presented by a friend or lawyer.

As Ham and van den Bos (2010) showed, when individuals utilize conscious processes, they tend to overrate the important of information they derived from personal observations. That is, this direct information is usually more salient than indirect information. When conscious processes are invoked, the capacity of attention is limited. Individuals must focus on a subset of information. Typically, they focus on salient cues. They will, therefore, be influenced unduly by direct information rather than indirect information.

In contrast, when individuals utilize unconscious processes, this limitation is circumvented. Decisions should not be shaped inordinately by direct information.

Ham and van den Bos (2010) conducted two studies that vindicate these suppositions. Participants received information about a genuine court case. In this case, a girl, who was younger than 18, stole a horse and carriage. She had not received permission from either her parents or the owner of this horse. Coincidentally, at the same time, a neighbor ignited some explosives, intended to deter birds. The explosives frightened the horse. The horse began to run erratically and was severely injured.

To some extent, all four parties were responsible and needed to pay damages. The girl has stolen the horse, but her parents are partly liable because of her age. The owner could have secured the horse more effectively. The neighbor could have been more prudent about the timing of this explosion. However, participants were not told which of these four parties were apportioned the most blame in the actual case.

To evoke conscious processing, some participants were instructed to consider the details carefully for three minutes before specifying the damages that each party should pay. To evoke unconscious processing, other participants received the same instructions, but were also asked to complete a distracting task during these three minutes, precluding conscious processing. Finally, some participants were asked to express their judgment immediately, without any delay.

Some participants received direct and vivid information that was, actually, extraneous to the case. For example, they observed a photograph of the injured horse--information that should not affect the relative liability of each party. Other participants received the same information indirectly, such as the testimony of a vet who described the injuries to the horse.

Overall, when unconscious processing but not conscious processing had been fostered, the judgments of participants aligned closely to the actual verdict, as reached by experienced court judges. Accordingly, unconscious processing was more likely than conscious processing or no processing to generate accurate judgments.

Furthermore, the inaccuracy of conscious processing was especially apparent after direct information, such as vivid but extraneous photographs, had been presented. Presumably, these participants overrated the significance of this salient, but extraneous, information. In addition, the inaccuracy of immediate judgments was especially apparent after indirect information has been presented. Indirect information may need to be processed before these insights can be utilized appropriately.

Detection of deception

Unconscious thinking might also enhance the capacity of individuals to detect deception. In particular, when individuals utilize their intuition, rather than apply rational principles--a style that overlaps with unconscious rather than conscious thinking--they can more readily determine whether or not a person is insincere (Albrechtsen, Meissner, & Susa, 2009).

In a study conducted by Albrechtsen, Meissner, and Susa (2009), for example, participants observed a series of ten confession statements, proposed by inmates of a correctional facility. Unbeknownst to participants, half of these confessions were true, and half of these confessions were false, as established independently. Participants then specified whether they assume the confessions were true or false.

For half of the participants, only a 5 second slice of each confession was shown, which tends to elicit intuitive processing (Ambady & Rosenthal, 1992). For the other participants, the entire confession was shown, which enables rational and systematic deliberations. When only a brief extract was presented, participants were more proficient in their capacity to differentiate sincere and insincere confessions.

In a subsequent study, some participants watched the entire confessions, but while performing a demanding cognitive activity--which precludes careful deliberation. Other participants did not complete this demanding activity. Finally, some of the participants were instructed to justify their judgment, merely to foster deliberation. Again, the capacity of individuals to differentiate sincere and insincere improved when deliberation was impeded.

According to Albrechtsen, Meissner, and Susa (2009), when individuals invoke their intuition, they become more sensitive to combinations of cues, such as vocal characteristics and facial expressions. Only subtle combinations of these cues seem to differ between true and false communication (for related findings, see DePaulo & Morris, 2004;; Hurd & Noller, 1988).

Likewise, ten Brinke, Stimson, and Carney (2013) argued that unconscious processes should be more sensitive to deception than conscious processes. That is, the capacity to detect lies is vital to survival. Therefore, humans most likely evolved to detect deception. Indeed, in response to lies, activity in the orbitofrontal cortex, anterior cingulate, and amygdala tends to escalate. The orbitofrontal cortex is vital to the capacity of individuals to understand the mental states of other individuals. The anterior cingulate is vital to their capacity to detect inconsistencies between for example, a goal and action. Finally, the amygdala is vital the detection of threats.

However, according to ten Brinke, Stimson, and Carney (2013), conscious processes might contaminate the capacity of unconscious processes to detect lies. That is, conscious processes might apply stereotypes or expectations about a person inappropriately: A person who conforms to the stereotype of integrity, perhaps because they work in a charitable sector, might be incorrectly assumed to be honest. When conscious processes are disrupted--such as if individuals need to devote their attention to other tasks--lie detection improves.

Indeed, ten Brinke, Stimson, and Carney (2013) showed that measures of unconscious processes do indeed gauge deception accurately. In one study, participants watched someone either speaking truthfully or dishonestly& they were not told which individuals were honest, however. An implicit association test was then administered to assess whether participants associate the photos of liars with deception and the photos of non-liars with veracity. In essence, they needed to press one of two buttons, depending on whether an item was synonymous with deception or veracity or whether a photo was correctly related to a specific name. Participants completed the task more effectively when the same button was assigned to synonyms of deception and photos of liars. These findings imply that participants associated deception with liars.

The second study was similar except that another procedure was used to gauge unconscious processes. On each trial, a photograph of a liar or non-liar appeared. Next, a word, such as genuine, was presented. Participants needed to decide whether the word relates to deception or veracity. They performed more effectively if words that were synonymous with deception followed photographs of liars.

Sensitivity to consequences

If individuals apply conscious deliberation, and thus utilize explicit rules, their behavior may be insensitive to consequences. That is, they might engage in behaviors that are not necessarily rewarded.

Research on the matching rule substantiates this possibility. Some famous baseball players, such as Mickey Mantle, Eddie Murray, and Pete Rose, could hit left handed or right handed. Poling, Weeden, Redner, and Foster (2011) explored whether or not these baseball players tended to conform to the matching rule--in which the extent to which these baseball players, for example, chose to hit left handed was associated with the proportion of success with this hand. However, the results indicate that all these batters used left handed less often than predicted from their success with this hand. This insensitivity to success can be ascribed to the tendency of these players to instead apply a rule: If the pitcher is left handed, bat right handed. If the pitcher is right handed, bat left handed. Because this rule was usually followed, their behavior was not as dependent on the consequences of their choices.

Integration of conscious and unconscious thinking

According to Nordgren, Bos, and Dijksterhuis (2011), to solve problems effectively, individuals should utilize both conscious and unconscious thought, because each mode offers distinct benefits. Indeed, they conducted research that attests to the benefits of both modes.

In the first study, participants needed to decide which of four apartments to rent. They received information about one attribute of each apartment in a random sequence. Like most studies in this field, participants were instructed to choose an apartment immediately, deliberate for four minutes and then choose, or complete a distracting activity for four minutes and then choose. However, in this study, another condition was included. Participants deliberated for two minutes and then were distracted for two minutes, enabling conscious and then unconscious thinking.

Relative to the other conditions, when participants engaged in this blend of conscious and then unconscious thinking, they were more likely to choose the best apartment. As another study showed, conscious thought and then unconscious thought was more effective than was the reverse order.

Priming versus accessing answers

Unconscious thought seems to uncover optimal solutions to difficult problems when the response represents a choice between several alternatives (e.g., Dijksterhuis & van Olden, 2006). However, unconscious thought does not necessarily uncover optimal solutions to difficult problems when the response involves emitting a word or phrase from an infinite number of possibilities. To illustrate, in one of the studies conducted by Zhong, Dijksterhuis, and Galinsky (2008), participants had to identify one word, such as "match", that is related to three other terms, such as "stick", "maker", and "point". Questions that were deliberately difficult were chosen. Unconscious thinking, compared to conscious thinking, did not improve the capacity of individuals to answer these questions.

Interestingly, however, unconscious thinking did increase the accessibility of words that represent the correct answers. That is, after completing this task, strings of letters, such as falc, appeared on a screen. Participants had to determine whether or not the strings were words. If participants had engaged in unconscious thinking, they can more rapidly recognize words that correspond to the previous answers (Zhong, Dijksterhuis, & Galinsky, 2008). In other words, unconscious thinking can increase the accessibility of correct answers, but does not necessarily translate these solutions into a form that can be reported consciously. In contrast, conscious thought might facilitate this translation into awareness.

Forms of unconscious thinking

Hogarth (2001) explicitly distinguish between intuition and instinct. Intuition, in contrast to instinct, evolves from learning and experience. In contrast, instincts represent more primitive inclinations, often adapted to environments that are uncommon today, such as contexts in which food needed to be sourced regularly. Instincts represent rapid, automatic reactions.

The association between unconscious thinking and intuition

Unconscious thinking theory assumes that unconscious thinking, in which deliberation is precluded, facilitates intuition, whereas conscious thinking entails reliance on rules and logic. Damian and Sherman (2013) applied the process dissociation procedures, developed by Jacoby (1991), to assess this possibility. This study showed that conscious thinking promoted more reliance on rules and deliberation than unconscious thinking& the two types of thoughts did not differ on reliance on intuition.

To undertake process dissociation, researchers need to design studies in which intuition and reliance on logic either generate the same conclusion, called congruence, or different conclusions, called incongruence. This design generates several equations, such as PCC = R + I (1 - R) and PII = I x (1 - R) in which PCC is the probability of correct decisions on congruent trials, R equals the probability of reliance on rules, I equals the probability of reliance on intuition and ICC equals the probability of incorrect decisions on incongruent trials. When these equations are combined, R = PCC - PII and I = PII / (1 - R). These equations can be utilized to estimate the extent to which people utilize intuition or depend on rules and deliberation.

Damian and Sherman (2013) conducted two studies in which this logic was utilized. For example, participants completed various problems, such as base-rate problems and laws of large numbers, in which intuition can generate correct or incorrect decisions. These studies showed the probability of reliance on deliberation was higher when conscious thinking was permitted& however, the probability of intuition did not differ between the two conditions. Arguably, however, unconscious thinking may be more likely to foster intuition on problems when such intuition is helpful and reliance on deliberation is unhelpful.

Empirical evidence

Satisfaction with decisions

To establish the benefits of unconscious thinking, some studies examine future satisfaction with previous decisions.For example, in a study conducted by Dijksterhuis and van Olden (2006), participants were asked to decide which of several abstract paintings they should purchase. Some participants were instructed to specify the merits and problems of each painting in sequence, representing conscious thinking. Other participants were instructed to observe the paintings briefly and decide immediately, rather than consciously, which painting they prefer. Finally, some participants observed the paintings briefly, but then completed a distracting task for several minutes, before reaching an intuitive and immediate decision.

Several weeks later, participants were asked to specify the amount of money they would need to receive before they would return the painting--a gauge of their satisfaction with this purchase. The individuals who had observed the paintings briefly, completed a distracting task, and then reached an intuitive decision were, several weeks later, the most satisfied with their purchase. This finding highlights the benefits of unconscious thinking when the alternatives differ on many ambiguous dimensions.

Accuracy of predictions

Unconscious thinking has also been shown to enhance the accuracy of predictions, especially in experts. In one study, conducted by Dijksterhuis, Bos, van der Leij, and van Baaren (2009), participants were asked to predict the outcome of soccer games. Some participants were asked to reach an immediate decision, precluding both conscious and unconscious thinking. Other participants were instructed to deliberate carefully for two minutes before reaching a decision. Finally some participants performed a cognitive task during this two minutes, to preclude conscious thinking about the soccer game and to facilitate unconscious thinking. Unconscious thinking generated the most accurate predictions, but only in people with solid knowledge of soccer. Presumably, unconscious thinking enabled individuals to integrate their extensive knowledge and experience.

Optimal solutions

Other studies have explored whether individuals are more likely to identify the optimal solution, as defined by some algorithm, if they apply conscious or unconscious thoughts. For example, participants might receive a mountain of information about several job applicants or roommates (e.g., Dijksterhuis, 2004;; Dijksterhuis, Bos, Nordgren, & Van Baaren, 2006). One of the job applicants or roommates is the most appropriate, according to the criteria that are stipulated. However, the volume of information precludes a systematic calculation of this solution. In these instances, according to these studies, unconscious thinking again optimizes decisions (for conflicting findings, see Newell, Wong, Cheung, & Rakow, 2008).

Expert decisions

Rather than focus on future satisfaction or optimal solutions, to assess whether unconscious thinking optimizes decisions, some studies compare the judgments of participants with the evaluations of experts. In a study conducted by Halberstadt and Green (2008), for example, participants watched a series of Olympic dives on video. They presented a rating out of 10, either without or after presenting reasons to justify their judgment. When participants were instructed to present reasons, their judgments were more likely to diverge from the assessments of experts.

Similarly, in a study conducted by Wilson and Schooler (1991), participants were asked to evaluate various brand of strawberry jam, only some of whom were instructed to justify their judgments with reasons. If participants were instructed to offer reasons, their evaluations were more likely to diverge from the assessments of contributors to a consumer magazine.

Contradictory evidence

The Newell, Wong, Cheung, and Rakow (2008) study

Newell, Wong, Cheung, and Rakow (2008), in a series of four studies, were unable to replicate the finding that unconscious thinking optimizes decisions. In their first study, participants needed to decide which of four apartments, which differed on ten attributes, they prefer. In addition, after selecting the apartment, they rated the importance of each attribute. Hence, the researchers could compute the utility of each apartment mathematically--by multiplying the benefits and drawbacks of each alternative by the corresponding importance of each attribute, called a weighted additive model.

Participants, generally, tended to select the apartment that is optimal, as defined by this model. Performance, however, did not differ between participants who were instructed to think consciously and participants who were instructed to think unconsciously. As Study 2 revealed, this pattern of results persisted even when more time elapsed between the presentation of stimuli and the selection of apartments. Likewise, this pattern of results persisted when all the information about each alternative was available while participants selected their preferred apartment (Newell, Wong, Cheung, & Rakow, 2008). Furthermore, as Study 3 showed, this pattern of findings was also observed when participants needed to choose one of four cars, which differed on 12 attributes--an example that was used by Dijksterhuis, Bos, Nordgren, and Van Baaren (2006). Finally, Newell, Wong, Cheung, and Rakow (2008), in their fourth study, showed that choices are biased by the most recent information--and this bias might even be most pronounced after unconscious thinking.

Newell, Wong, Cheung, and Rakow (2008), however, did not examine whether unconscious thinking enhances decisions when the implications of attributes are more ambiguous, unpredictable, and undefined. Hence, the applicability of their findings to other contexts remains to be tested. In addition, personality system interaction theory implies that unconscious thinking might be most effective when individuals feel composed, not agitated (cf., Bolte, Goschke, & Kuhl, 2003)--a proposition that also awaits further investigation (see Personality systems interaction theory).

Duration of unconscious thought

According to unconscious thinking theory, as the duration of unconscious thinking increases, decisions are more likely to be correct. Huizenga, Wetzels, van Ravenzwaaij, and Wagenmakers (2012) conducted a study that was intended to assess this hypothesis. This study, however, did not vindicate this premise.

In particular, participants received information about four cars, such as whether the sound system was good or whether a sun roof had been installed. Some of the attributes of each car were positive, and other attributes were negative. Their task was to choose the best car-defined as the vehicle with the most positive attributes. After receiving this information, some participants were distracted by another task for 2, 4 or 8 minutes. Other participants were permitted to deliberate on their decision carefully. The percentage of correct responses did not depend on whether the period of distraction, in which unconscious thought is assumed to prevail, was 2, 4 or 8 minutes. Indeed, unconscious thought was not more likely than conscious thought to generate more accurate answers.

Availability of information

One criticism of past studies is that information about the alternatives, such as four cars, is usually presented in an unrealistic format. That is, only one attribute is presented at a time. In life, when individuals need to decide between several alternatives, they can access all the information simultaneously. That is, all the information may be summarized on a page.

When all the information can be accessed simultaneously,conscious thought tends to outperform unconscious thought, as demonstrated by Huizenga, Wetzels, van Ravenzwaaij, and Wagenmakers (2012). That is, in their study, participants received information about four cars, such as whether the sound system was good or whether a sun roof had been installed. One attribute of one car was presented at a time. After receiving this information, some participants were distracted for four minutes, representing unconscious thought. Other participants could skim the information for four minutes instead. This information either was presented haphazardly or was structured coherently: that is, the attributes were arranged in a logical order. Performance was most effective if conscious thought was permitted, especially if the material was structured coherently.

Prevailing strategy

To decide which of several alternatives, such as four cars or four apartments, individuals should use, several strategies can be utilized. Individuals can focus only on the most important attribute. Alternatively, individuals can weight all the attributes according to their importance. According to unconscious thinking theory (e.g., Dijksterhuis et al., 2006), unconscious thinking may be more likely than conscious thinking to weight the attributes. Huizenga, Wetzels, van Ravenzwaaij, and Wagenmakers (2012) did not uncover any evidence of this premise, however. That is, in this study, one car was optimal if a weighting strategy was used, and another car was optimal if people focused on the most important attribute. The majority of individuals, regardless of whether thinking was conscious or unconscious, seemed to focus on the most important attribute only.

Factors that moderator the benefits of unconscious thinking

Mood and affect

These controveries imply that several factors might moderate the benefits of unconscious thinking on outcomes. Mood, for example, might determine whether intuitive or unconscious strategies are more suitable than conscious and deliberate strategies. At least, mood might affect which of these strategies is likely to evoke decisions that promote satisfaction rather than regret.

This possibility was raised by de Vries, Holland, and Witteman (2009). These authors argued that happy moods often encourage an intuitive, unconscious approach, whereas sad moods often encourage a more deliberate, conscious approach. Accordingly, a happy mood seems congruent with unconscious thinking& in this mood, therefore, unconscious thinking should at least enhance the sense of certainty or satisfaction that individuals experience after they reach decisions. Likewise, a sad mood seems congruent with conscious thinking& in this mood, conscious thinking should foster this sense of certainty and satisfaction.

To explore this possibility, in the study conducted by de Vries, Holland, and Witteman (2009), participants watched a happy or sad movie clip. Next, participants were asked to reach a decision either intuitively or deliberately--which involved choosing a flask from a range of alternatives. Happy individuals were more likely to perceive this flask as valuable if they reached the decision intuitively. Sad individuals were more likely to perceive this flask as valuable if they reached the decision deliberately.

Similarly, Hicks, Cicero, Trent, Burton, and King (2010) also showed that positive moods facilitate the application of intuition, analogous to unconscious thinking. Consistent with this proposition, the capacity to identify associations between three words that are remotely associated with each other was positively related to intuition, but only when positive affect was elevated (Hicks, Cicero, Trent, Burton, & King, 2010).

Nature of the task

The nature of a task also determines whether or not rational justifications of decisions are detrimental. In a study conducted by McMackin and Slovic (2000), participants completed two tasks. The first task involved evaluations of advertising, which entails subjective or affective processes. The second task involved the estimation of uncertain numbers, such as the length of the Amazon River, which entails more rational or analytical processes. Some of the participants were instructed to justify their answers with reasons& other participants did not receive this instruction.

The instruction to justify responses undermined performance on the advertising task but enhanced performance on the number estimation activity. Thus, deliberation seems to impair performance on tasks that demand affective or intuitive processes but can facilitate performance on tasks that demand rational and logical processes (for related findings, see Hammond, Hamm, Grassia, & Pearson, 1987).

Conceivably, the verbal processes that mediate deliberation could stifle intuition (cf., Schooler, Ohlsson, & Brooks, 1993). Consistent with this premise, when individuals engage in verbal processing, recognition of stimuli, which demands intuitive operations, is impaired (Schooler & Engster-Schooler, 1990), called verbal overshadowing. Similarly, Hogarth (2001) maintains that exemplary decision making demands a comprehensive understanding of the contexts in which deliberation and intuition are most applicable.

Measures and manipulations of unconscious thinking

No measures have been developed specifically to assess whether individuals apply conscious or unconscious thinking to solve problems. Nevertheless, many analogous scales have been constructed. Novak and Hoffman (2009), for example, constructed a measure that determines whether individuals applied deliberate, rational processes--analogous to conscious thinking--or intuitive, experiential processes--analogous to unconscious thinking to reach decisions or judgments (see Cognitive experiential theory). This measure, however, does not distinguish between impulses that are evoked immediately and intuitions that evolve over time.

Several protocols have been developed a evoke conscious or unconscious thinking. Usually, to evoke conscious thinking, participants are asked to reflect upon the benefits and drawbacks of various options (see Dijksterhuis, 2004;; Dijksterhuis & van Olden, 2006) or the reasons to justify their choices (e.g., Halberstadt & Green, 2008). To evoke unconscious thinking, individuals are distracted for several minutes (Dijksterhuis & van Olden, 2006) or merely not asked to justify their choices (e.g., Halberstadt & Green, 2008).

Many other procedures could evoke conscious or unconscious thinking. When the time that is available to complete a task is limited, individuals are more inclined to apply their intuition than deliberately carefully (Ambady & Rosenthal, 1992). That is, in many studies, participants observe thin slices of behavior. They might watch 5 seconds of an extended speech. Participants can often evaluate a person accurately, even after observing only these fleeting clips (e.g., Ambady Hallahan, & Conner, 1999;; Ambady & Rosenthal, 1993).

Some research indicates that such thin slices might foster a reliance on intuitive--or unconscious--processes. In a study reported by Albrechtsen, Meissner, and Susa (2009), for example, participants observed a series of ten confession statements, proposed by inmates of a correctional facility. When participants observed limited slices of behavior, they could more accurately differentiate sincere and insincere statements, and this capacity seems to reflect intuitive processes. That is, other conditions that foster intuitive processes also enhance this capacity.

Similarly, when individuals need to complete more than one demanding activity within a limited duration, they also apply unconscious, intuitive processes. Multiple tasks also improves the ability of individuals to discern dishonesty (Albrechtsen, Meissner, & Susa, 2009).

Alternative explanations

Mental shift fixing

Conceivably, some of the purported benefits of unconscious thinking, especially in the realm of creativity, might involve mental set shifting. In particular, Dijksterhuis and Meurs (2006) showed that unconscious thought can promote more creative responses to questions--that is, responses that deviated from some algorithm or pattern. In one of their studies, for example, participants were assigned the task to identify names for novel shapes of pasta. In addition, they received a few examples, all ending in the letter i. Before presenting their solutions, some of the participants engaged in a distracting task for a few minutes, representing the unconscious thinking condition. Other participants could reflect upon the solutions consciously.

Participants who engaged in unconscious thinking, not conscious deliberation, were more inclined to suggest names that did not in the letter i--departing from the prevailing pattern. According to unconscious thinking theory (Dijksterhuis & Meurs, 2006), unconscious thought might facilitate the departure from conventional associations and algorithms. In other words, unconscious thoughts can facilitate remove associations.

Alternatively, mental set shifting, also called forgetting fixation, can explain some of these benefits. Temporary distractions from some task can diminish the accessibility of previous thoughts--thoughts might have been misleading. Hence, merely divorcing attention from ineffective or misleading thought patterns can improve subsequent insight or creativity (e.g., Schooler, Ohlsson, & Brooks, 1993;; Smith, & Blankenship, 1989).

Nevertheless, several studies indicate that unconscious thinking cannot be entirely ascribed to mental set shifting--but instead represents active processes. In particular, the benefits of unconscious thinking dissipate if individuals do not believe they will need to present answers after the period of distraction (see Bos, Dijksterhuis, & van Baaren 2008;; Zhong, Dijksterhuis, & Galinsky, 2008). That is, only if participants form the goal to solve the problem will the benefits of unconscious thought emerge.

On-line versus memory processing

Lassiter, Lindberg, Gonzalez-Vallejo, Bellezza, and Phillips (2009) offered an alternative explanation to accommodate at least some of the observations that, typically, are ascribed to unconscious thinking theory. In particular, in the condition that putatively elicits unconscious thinking, participants are likely to form an impression as they accumulation information about each option. After the period of distraction, they are inclined to utilize this impression to decide which of the alternatives to select.

In contrast, in the condition that putatively elicits conscious thinking, participants are instructed to consider the merits and drawbacks of each alternative. In response to this instruction, participants might strive to recall the key features of each option. Then, to decide which alternative to select, their judgment might be derived from the retrieved information only--which compromises their decisions.

Lassiter, Lindberg, Gonzalez-Vallejo, Bellezza, and Phillips (2009) undertook a pair of studies, which seem to vindicate this alternative explanation. In their study, participants 12 attributes of 4 cars were presented in a random order. Only one of the cars was associated with more positive than negative features. As with previous studies in this domain, some participants were instructed to deliberately carefully or were distracted with an alternative task, intended to facilitate unconscious thinking.

Furthermore, and unique to this study, before the attributes were presented, some participants were instructed to form an impression of each car. Other participants were told to memorize the attributes. If instructed to form an impression, participants were less inclined to select the correct car if instructed to deliberate carefully. In contrast, if instructed to memorize attributes, participants were more inclined to select the correct car. A second study showed this pattern was observed only when need for cognition was high (Lassiter, Lindberg, Gonzalez-Vallejo, Bellezza, & Phillips, 2009).

According to Lassiter, Lindberg, Gonzalez-Vallejo, Bellezza, and Phillips (2009), when instructed to deliberate carefully, individuals strive to retrieve the attributes. This retrieval process is more likely to be effective--and hence the final decision is more likely to be suitable--if participants strive to memorize the information from the outset.

One possible complication, however, is that instructions to memorize information might subsequently stifle unconscious thinking. After individuals engage in a verbal task, they become more likely to adopt a rational or deliberate rather than intuitive or unconscious processing style (Novak & Hoffman, 2009). Hence, these instructions could stifle any subsequent attempts to trust intuition--a key facet of unconscious thinking.

Strick, Dijksterhuis, and van Baaren (2010) conducted a pair of studies that challenge the account that was proposed by Lassiter, Lindberg, Gonzalez-Vallejo, Bellezza, and Phillips (2009). Like other studies, participants received positive and negative information about four alternatives--in this instance, four potential roommates. Participants were instructed to choose a roommate immediately after the information was presented, after a period of deliberation, or after a period of distraction, to enable unconscious processing. However, unlike previous studies, after reaching their choice, participants were asked to indicate when they chose this roommate.

If participants indicated they selected this roommate while reading the information or immediately after receiving this information, they seldom chose the roommate with the most positive attributes. In contrast, if participants indicated they selected this roommate not before they were asked to reach a choice, they performed more effectively--but only when unconscious thinking was encouraged. That is, participants chose the best roommate only if they delayed their choice to after the period of distraction, confirming the benefits of unconscious thinking.


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