Comparing the phenomenological qualities of stimulus-independent thought, stimulus-dependent thought and dreams using experience sampling

Humans spend a considerable portion of their lives engaged in 'stimulus-independent thoughts' (SIT), or mental activity that occurs independently of input from the immediate external environment. Although such SITs are, by definition, different from thoughts that are driven by stimuli in one's external environment (i.e. stimulus-dependent thoughts; SDTs), at times, the phenomenology of these two types of thought appears to be deceptively similar. But how similar are they? We address this question by comparing the content of two types of SIT (dreaming and waking SITs) with the content of SDTs. In this 7 day, smartphone-based experience-sampling procedure, participants were intermittently probed during the day and night to indicate whether their current thoughts were stimulus dependent or stimulus independent. They then responded to content-based items indexing the qualitative aspects of their experience (e.g. My thoughts were jumping from topic to topic). Results indicate substantial distinctiveness between these three types of thought: significant differences between at least two of the three mental states were found across every measured variable. Implications are discussed. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

Stereotype distinctiveness: how counterstereotypic behavior shapes the self-concept

Three experiments examined the relationship between distinctiveness and self-schematicity. Experiment 1 revealed that people were more likely to be self-schematic in domains of strong performance when they felt distinct from family and peers in those domains. Experiments 2 and 3 extended this finding into the arena of stereotypes by demonstrating that people were more likely to be self-schematic in domains of strong performance when their performance was counterstereotypic rather than stereotypic. In particular, African Americans and women were more likely to be schematic for intelligence than Caucasians and men if they performed well academically, whereas Caucasians-especially men-were more likely than African Americans to be schematic for athletics if they performed well athletically. These results suggest that counterstereotypic behavior plays a uniquely powerful role in the development of the self-concept.

Stereotype distinctiveness: how counterstereotypic behavior shapes the self-concept

Three experiments examined the relationship between distinctiveness and self-schematicity. Experiment 1 revealed that people were more likely to be self-schematic in domains of strong performance when they felt distinct from family and peers in those domains. Experiments 2 and 3 extended this finding into the arena of stereotypes by demonstrating that people were more likely to be self-schematic in domains of strong performance when their performance was counterstereotypic rather than stereotypic. In particular, African Americans and women were more likely to be schematic for intelligence than Caucasians and men if they performed well academically, whereas Caucasians-especially men-were more likely than African Americans to be schematic for athletics if they performed well athletically. These results suggest that counterstereotypic behavior plays a uniquely powerful role in the development of the self-concept.

Justification effects on the judgment of analogy

Many of us share a strong intuition that justification forces us to better understand the situations we face. And there is substantial evidence indicating that this is often the case. However, there is a growing body of research showing that, under certain circumstances, explanation and justification can impair performance on a variety of cognitive tasks. In the present research, the effects of justification on judgment of the soundness of analogies were examined. Subjects judged the quality of the match between pairs of stories with varying degrees of superficial and analogical similarity. Experimental subjects either provided reasons for their judgments or wrote recollections of the target stimuli. These subjects rated the match between stimulus pairs as more sound than did control subjects. Also, providing reasons led to poorer discrimination between superficially similar aspects of the stimuli and analogous aspects. Explanations of these findings are proposed, and implications for problem solving and confidence judgment are discussed.

The distinctions of false and fuzzy memories

Fuzzy-trace theory has recently been used to account for various types of "false memories" (Brainerd & Reyna, 1998, this issue). Although components of fuzzy-trace theory-in particular the distinction between gist and verbatim traces-overlap with distinctions made in other theories of memory, those in fuzzy-trace theory provide an illuminating account of the conditions under which semantic associates of previously seen items are erroneously recognized. However, the theory is less useful in explaining misinformation effects. Fuzzy-trace theory's differential success in accounting for these two types of errors follows from one of its central implications: whereas misinformation effects involve false memories, the erroneous recognition of related lures is due to a reliance on authentic, but underspecified, gist memories. As its name suggests, fuzzy-trace theory is best at explaining memory errors resulting from fuzzy traces. Consistent with this view, fuzzy-trace theory helps to explain another source of memory errors (verbal overshadowing of nonverbal memories) that may also be best characterized as resulting from a reliance on fuzzy, rather than false, memories.

Attenuating verbal overshadowing through color retrieval cues

Five experiments showed that interference resulting from verbalizing visual stimuli (verbal overshadowing) can be reduced by reintroducing visual cues present at encoding. Object color and background color were used as cues. Participants learned either easy- or hard-to-name figures and then performed an image rotation task. Before performing the imagery task, participants were re-presented with the color patch associated with each figure. Color re-presentation attenuated the impairment associated with easy-to-name stimuli (Experiment 1) as well as labeled hard-to-name stimuli (Experiment 2). However, background color cues had no effect on imagery performance (Experiment 3). Experiment 4 showed that naming the object colors at encoding makes color retrieval cues ineffective. Finally, Experiment 5 showed that object color cues can help participants to overcome previously exhibited impairment resulting from covert verbalization.

Attenuating verbal overshadowing through color retrieval cues

Five experiments showed that interference resulting from verbalizing visual stimuli (verbal overshadowing) can be reduced by reintroducing visual cues present at encoding. Object color and background color were used as cues. Participants learned either easy- or hard-to-name figures and then performed an image rotation task. Before performing the imagery task, participants were re-presented with the color patch associated with each figure. Color re-presentation attenuated the impairment associated with easy-to-name stimuli (Experiment 1) as well as labeled hard-to-name stimuli (Experiment 2). However, background color cues had no effect on imagery performance (Experiment 3). Experiment 4 showed that naming the object colors at encoding makes color retrieval cues ineffective. Finally, Experiment 5 showed that object color cues can help participants to overcome previously exhibited impairment resulting from covert verbalization.

The verbal overshadowing effect: why descriptions impair face recognition

Three experiments explored the verbal overshadowing effect, that is, the phenomenon that describing a previously seen face impairs recognition of this face. There were three main results: First, a verbal overshadowing effect was obtained both when subjects were provided with and when they generated a description of an earlier seen face. Second, instructing subjects at the time of test to be aware of potentially competing memories did not improve, and may even have worsened, recognition performance when the subjects had generated a description of the target face. However, these instructions improved performance and eliminated the verbal overshadowing effect when subjects were provided with someone else's description of the target face. Third, recognition of the target face was disrupted when subjects described a completely different face, such as their parent's face or a face of the opposite sex. The results are discussed in relation to two potential mechanisms: source confusion between previously encoded visual and verbal representations of the face and a shift in processing of the test faces at recognition.

Verbal vulnerability of perceptual expertise

Three experiments explored the role of perceptual expertise in mediating the finding (termed verbal overshadowing) that describing a face can impair later recognition. In Experiment 1, verbalization impaired White participants' recognition of White faces (expert domain) but not African American faces (novice domain). In Experiment 2, judges attempted to identify targets on the basis of the verbal descriptions generated in Experiment 1. Experiment 2 revealed a significant relationship between verbalization participants' recognition performance and yoked judges' identification performance for other-race but not own-race faces, suggesting that other-race recognition may involve a unique reliance on "verbalizable" information. In Experiment 3, the interaction between verbalization and race of face was replicated with upright faces but was attenuated with inverted recognition arrays (a manipulation that reduces the influence of configural information). Collectively, these findings suggest that verbalization may disrupt the nonreportable configural processes associated with recognizing stimuli with which one is an expert.

Verbal vulnerability of perceptual expertise

Three experiments explored the role of perceptual expertise in mediating the finding (termed verbal overshadowing) that describing a face can impair later recognition. In Experiment 1, verbalization impaired White participants' recognition of White faces (expert domain) but not African American faces (novice domain). In Experiment 2, judges attempted to identify targets on the basis of the verbal descriptions generated in Experiment 1. Experiment 2 revealed a significant relationship between verbalization participants' recognition performance and yoked judges' identification performance for other-race but not own-race faces, suggesting that other-race recognition may involve a unique reliance on "verbalizable" information. In Experiment 3, the interaction between verbalization and race of face was replicated with upright faces but was attenuated with inverted recognition arrays (a manipulation that reduces the influence of configural information). Collectively, these findings suggest that verbalization may disrupt the nonreportable configural processes associated with recognizing stimuli with which one is an expert.

Composites, compromises, and CHARM: what is the evidence for blend memory representations?

Metcalfe's (1990) distributed memory model simulates many misinformation effects by assuming representations that superimpose information from multiple sources. In the present article, two types of evidence are reviewed for such "blend" representations: composite recollections, including items from both the original and postevent sources (e.g., a previously seen intersection is remembered with a subsequently suggested stop sign), and compromise recollections, including features that cannot be exclusively associated with either source (e.g., a green car that was later suggested to be blue is remembered as bluish green). The considerable evidence for composite recollections provides little support for blend representations. Compromise recollections, though seemingly more persuasive, are both rare and interpretable without postulating blend representations. Speculation is made about potential findings that would support blend representations.

Thinking too much: introspection can reduce the quality of preferences and decisions

In Study 1, college students' preferences for different brands of strawberry jams were compared with experts' ratings of the jams. Students who analyzed why they felt the way they did agreed less with the experts than students who did not. In Study 2, college students' preferences for college courses were compared with expert opinion. Some students were asked to analyze reasons; others were asked to evaluate all attributes of all courses. Both kinds of introspection caused people to make choices that, compared with control subjects', corresponded less with expert opinion. Analyzing reasons can focus people's attention on nonoptimal criteria, causing them to base their subsequent choices on these criteria. Evaluating multiple attributes can moderate people's judgments, causing them to discriminate less between the different alternatives.

Composites, compromises, and CHARM: What is the evidence for blend memory representations?

Metcalfe's (1990) distributed memory model simulates many misinformation effects by assuming representations that superimpose information from multiple sources. In the present article, two types of evidence are reviewed for such "blend" representations: composite recollections, including items from both the original and postevent sources (e.g., a previously seen intersection is remembered with a subsequently suggested stop sign), and compromise recollections, including features that cannot be exclusively associated with either source (e.g., a green car that was later suggested to be blue is remembered as bluish green). The considerable evidence for composite recollections provides little support for blend representations. Compromise recollections, though seemingly more persuasive, are both rare and interpretable without postulating blend representations. Speculation is made about potential findings that would support blend representations.

Thinking too much: Introspection can reduce the quality of preferences and decisions

In Study 1, college students' preferences for different brands of strawberry jams were compared with experts' ratings of the jams. Students who analyzed why they felt the way they did agreed less with the experts than students who did not. In Study 2, college students' preferences for college courses were compared with expert opinion. Some students were asked to analyze reasons; others were asked to evaluate all attributes of all courses. Both kinds of introspection caused people to make choices that, compared with control subjects', corresponded less with expert opinion. Analyzing reasons can focus people's attention on nonoptimal criteria, causing them to base their subsequent choices on these criteria. Evaluating multiple attributes can moderate people's judgments, causing them to discriminate less between the different alternatives.

Verbal overshadowing of visual memories: some things are better left unsaid

It is widely believed that verbal processing generally improves memory performance. However, in a series of six experiments, verbalizing the appearance of previously seen visual stimuli impaired subsequent recognition performance. In Experiment 1, subjects viewed a videotape including a salient individual. Later, some subjects described the individual's face. Subjects who verbalized the face performed less well on a subsequent recognition test than control subjects who did not engage in memory verbalization. The results of Experiment 2 replicated those of Experiment 1 and further clarified the effect of memory verbalization by demonstrating that visualization does not impair face recognition. In Experiments 3 and 4 we explored the hypothesis that memory verbalization impairs memory for stimuli that are difficult to put into words. In Experiment 3 memory impairment followed the verbalization of a different visual stimulus: color. In Experiment 4 marginal memory improvement followed the verbalization of a verbal stimulus: a brief spoken statement. In Experiments 5 and 6 the source of verbally induced memory impairment was explored. The results of Experiment 5 suggested that the impairment does not reflect a temporary verbal set, but rather indicates relatively long-lasting memory interference. Finally, Experiment 6 demonstrated that limiting subjects' time to make recognition decisions alleviates the impairment, suggesting that memory verbalization overshadows but does not eradicate the original visual memory. This collection of results is consistent with a recording interference hypothesis: verbalizing a visual memory may produce a verbally biased memory representation that can interfere with the application of the original visual memory.

Creating new memories that are quickly accessed and confidently held

In two experiments involving a total of 542 subjects, a series of slides depicting a burglary was shown. After the initial event, subjects were exposed to one or more narratives about the event that contained some misinformation or neutral information about four critical details. Finally, subjects were tested on their memories of what they saw, and their reaction times and confidence levels were measured. When subjects took a standard test in which the misinformation item was a possible response option, they responded very quickly and confidently when making this incorrect choice. Misled subjects responded as quickly and confidently to these "unreal" memories as they did to their genuine memories. It does not seem, then, that the misinformation effect arises from a large proportion of subjects who must resolve a conflict between two memories when they are tested, a conflict that would be expected to take time. When subjects took a modified test in which the misinformation item was not a possible response, misled subjects were as accurate as were controls, but they responded more slowly, regardless of whether they ultimately chose the right or wrong option. These findings indicate that misinformation does introduce some form of interference not detected by a simple test of accuracy.

Qualities of the unreal

Witnesses to complex events often recall nonexistent objects after being exposed to misleading postevent information. The present series of experiments investigated whether descriptions of these "unreal" memories differ from those of memories based on perception. In Experiment 1 subjects viewed a slide sequence depicting a traffic accident. In one condition, the sequence included a slide involving a yield sign. In a second condition, subjects did not see the sign but merely had its existence suggested. Many subjects in both groups later reported seeing the sign, and these subjects provided verbal descriptions. Descriptions that resulted from suggestion were longer and contained more hedges, more reference to cognitive operations, and fewer sensory details. Experiment 2 replicated these findings with a different object. Experiment 3 investigated judges' ability to discriminate the source of the descriptions based on perception and suggestion. Although judges often employed the appropriate criteria, their performance was only slightly above chance. Experiments 4 and 5 revealed that providing judges with clues regarding differences between perceived and suggested memories facilitated discrimination. The results of these experiments indicate that subtle differences exist between perceived and suggested memories, that people have a minimal ability to detect these differences, and that instructions can improve that ability.

Qualities of the unreal

Witnesses to complex events often recall nonexistent objects after being exposed to misleading postevent information. The present series of experiments investigated whether descriptions of these "unreal" memories differ from those of memories based on perception. In Experiment 1 subjects viewed a slide sequence depicting a traffic accident. In one condition, the sequence included a slide involving a yield sign. In a second condition, subjects did not see the sign but merely had its existence suggested. Many subjects in both groups later reported seeing the sign, and these subjects provided verbal descriptions. Descriptions that resulted from suggestion were longer and contained more hedges, more reference to cognitive operations, and fewer sensory details. Experiment 2 replicated these findings with a different object. Experiment 3 investigated judges' ability to discriminate the source of the descriptions based on perception and suggestion. Although judges often employed the appropriate criteria, their performance was only slightly above chance. Experiments 4 and 5 revealed that providing judges with clues regarding differences between perceived and suggested memories facilitated discrimination. The results of these experiments indicate that subtle differences exist between perceived and suggested memories, that people have a minimal ability to detect these differences, and that instructions can improve that ability.

The fate of memory: comment on McCloskey and Zaragoza

McCloskey and Zaragoza (1985) argue that misleading postevent suggestions do not affect the availability of originally encoded information. Their hypothesis stems from empirical work using a modified paradigm in which no effect of postevent information is observed. Although their "no impairment" hypothesis is plausible, careful consideration of the predictions of their experimental test suggests that it may be insufficiently sensitive to reveal the impact of postevent information. A small effect of postevent information can be observed when their paradigm is repeated with a more sensitive recognition test. McCloskey and Zaragoza's no impairment hypothesis is also difficult to reconcile with numerous reports of "blend" memories that reflect a compromise between the original and postevent information.

The fate of memory: Comment on McCloskey and Zaragoza

McCloskey and Zaragoza (1985) argue that misleading postevent suggestions do not affect the availability of originally encoded information. Their hypothesis stems from empirical work using a modified paradigm in which no effect of postevent information is observed. Although their "no impairment" hypothesis is plausible, careful consideration of the predictions of their experimental test suggests that it may be insufficiently sensitive to reveal the impact of postevent information. A small effect of postevent information can be observed when their paradigm is repeated with a more sensitive recognition test. McCloskey and Zaragoza's no impairment hypothesis is also difficult to reconcile with numerous reports of "blend" memories that reflect a compromise between the original and postevent information.