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Inner speech: A neglected phenomenon

 

 

 

 

 

 

Alain MORIN

Department of Psychology, Mount Royal College

4825 Mount Royal Gate S.W., Calgary, Alberta, Canada T3E 6K6

Phone: 403-440-7069

Fax: 403-440-7027

E-mail: amorin@mtroyal.ca

 

 

 

 

 

 

 

Abstract

 

Inner speech arguably plays a central role in human consciousness, and yet, compared to other key psychological phenomena it seems to be somewhat neglected. Two studies were conducted to test the hypothesis that inner speech may be under-cited in the literature and might not have received its share of attention as a research area. Study 1 investigated how frequently inner speech and related terms were mentioned in Introductory Psychology textbooks. Only 7 out of 32 textbooks (21.8%) cited either inner speech, self-talk, private speech, or self-statements in their subject indexes. Study 2 compared citation frequency in PsycINFO for inner speech and related terms to 103 key psychological concepts and phenomena in peer-reviewed journal articles. The average citation frequency for all psychological terms was 1719; by comparison, inner speech was cited 52 times. 84.5% of all terms were cited more often than inner speech. Taken together these observations suggest that inner speech does tend to be overlooked, not so much because it is unimportant but probably because it is taken for granted.

Inner speech: A neglected phenomenon

 

There is no doubt that inner speech represents a central process in consciousness and psychology. People report that approximately one fourth of their conscious waking life is made up of silent verbal thinking (Heavey & Hurlburt, 2008). In one study (Winsler et al., 2006), 96% of all adult participants indicated that they sometimes talk to themselves aloud when alone. Self-directed speech (first as private speech in children and then as inner speech in adults) has been shown to play a primary role in the regulation of thought and behavior (Fernyhough & Fradley, 2005; Fuson, 1979; Vygotsky, 1943/1962). All features of normal language functions (e.g., reading, writing, speaking, calculating) entail intact inner speech; consequently, loss of inner speech caused by brain damage leads to aphasia, agraphia, alexia, and acalculia (Levine & al., 1982). Verbal short-term memory engages a “phonological loop” (Baddeley & Hitch, 1974) that basically constitutes inner speech; autobiographical memory also involves inner speech, as recent research indicates that personal episodes are often encoded and retrieved in words (Larsen & al., 2002). Self-talk also plays a role in task switching performance (Miyake et al., 2004), remembering the goals of action (Meacham, 1979), and self-awareness (Morin & Michaud, 2007; Steels, 2003). When distorted, inner speech is frequently implicated in various forms of psychological disorders such as schizophrenia, social anxiety, and depression (e.g., Allen et al., 2007; Beazley et al., 2001).

Given the central role inner speech obviously plays in human cognition, memory, and consciousness, one would expect frequent reference to it in the scientific literature, as well as rich coverage in general textbooks and specialized handbooks and encyclopedias. Remarkably this does not seem to be the case. As Kinsbourne notes (2000, p. 120), “… inner speech is neglected at Millenium’s end, not even mentioned in the Handbook of Neurolinguistics (1998).” Indeed this statement also applies to the Handbook of Self and Identity (2003) and the Blackwell Companion to Consciousness (2007). I present below two studies conducted to expand on Kinsbourne’s observation that inner speech seems to be a neglected phenomenon. Study 1 investigated the extent to which inner speech and related terms were listed in subject indexes of Introductory Psychology textbooks. Study 2 calculated the number of peer-reviewed journal articles that cited inner speech and related terms in their title between 1900 and 2009; this number was taken as an exploratory objective measure of research output which was then compared to the number of citations for other key psychological concepts and phenomena. Study 1 thus attempted to examine the possibility that inner speech is under-cited in the Introductory Psychology literature, whereas Study 2 explored the notion that as a research area inner speech might not have received its share of attention.

 

Study 1

Method

The main purpose of Study 1 was to investigate the frequency with which inner speech was mentioned in Introductory Psychology textbooks. The rationale behind specifically focusing on Introductory Psychology textbooks was as follows. As seen above, inner speech arguably constitutes a key concept in psychology; one would thus expect that it would be introduced to first-year students. Also, inner speech has been studied from various perspectives, most notably cognition, language, development, social cognition, memory, consciousness, and psychotherapy. Each of these perspectives is typically covered as a full chapter in Introductory Psychology textbooks, thus increasing the likelihood that inner speech should be mentioned.

The present investigator gathered as many recent textbooks as possible by consulting his private collection, by asking sales and editorial representatives to provide free copies, and by borrowing textbooks from colleagues. A total of 32 Introductory Psychology textbooks were collected and used (see Table 1 in the Results section below). Note that this sampling process was not meant to be exhaustive—an ultimately impossible task to achieve—but merely convenient while unbiased. The next step consisted in scanning through each textbook’s subject index for the term “inner speech” and related words. Many equivalent expressions are used in the literature to refer to the phenomenon of inner speech (Morin, 2009), including “propositional thought”, “subvocal speech”, “covert speech”, “self-referent speech”, “internal dialogue”, “internal monologue”, “auditory imagery”, “subvocalizations”, “subvocal articulation”, “utterances”, “self-verbalizations”, “acommunicative speech”, and “speech-for-self”. However, by far the most commonly used terms for inner speech are “private speech”, “self-talk”, and “self-statements”. Thus, the search was limited to “inner speech” and these three expressions.

 

Results

Table 1 presents the textbook analysis performed in Study 1. It contains (1) the author(s) of each textbook, (2) the editor, (3) the year of publication and edition, (4) the title, and (5) the result of the study per se—i.e., were the word “inner speech” and related terms listed in the subject index of the textbook (YES) or not (NO)? Only 7 out of 32 Introductory Psychology textbooks (21.8%) mentioned either inner speech, self-talk, private speech, or self-statements in their subject indexes. Stated differently: 78.2% of all textbooks in the current sample did not make a single reference to inner speech and related terms. Furthermore, closer analysis of those few textbooks that did cite inner speech and other expressions indicated that these mentions were extremely brief. To illustrate, Kosslyn and Rosenberg (2003) and Wade et al. (2007) both only dedicate one paragraph to private speech in their respective chapters on developmental psychology when discussing Vygotsty’s work. Nevid (2003, p. 563) has only one sentence on self-talk in the entire textbook (under psychotherapy), which reads: “In Kevin’s treatment, gradual exposure was combined with calming self-talk, such as telling himself to calm down and relax.” Likewise, Lilienfeld et al.’s analysis (2009, p. 689) of inner speech is summarized as follows: “Therapies modify patients’ self-statements, that is, their ongoing mental dialogue…” It is worth stressing that in this sample, the few textbooks that did cover inner speech did not produce a single in-depth section on the topic that would have provided an historical background and discussion of measurement techniques, development of private speech, neuroanatomy, functions of inner speech, dysfunctional self-talk, connections to consciousness, and so forth.

 

Table 1. Frequency of mentions to inner speech and related terms in subject indexes of 32 Introductory Psychology textbooks.

 

Study 2

Method

The goal of Study 2 was to compare citation frequency for inner speech and related expressions to other key psychological concepts and phenomena in peer-reviewed journal articles. The terms “inner speech”, “private speech”, “self-talk”, and “self-statements” utilized in Study 1 were used again in Study 2. Selection of key terms to which inner speech citation frequency would be contrasted was established by carefully scrutinizing the American Psychological Association (APA)’s Glossary. This list contains 643 key psychological terms with definitions presented in alphabetical order; it is supplied by Gerrig and Zimbardo (2002) and can be found on the organization’s website at www.psychologymatters.org/glossary.html. The glossary is assumed to represent an authoritative and representative directory of the most important concepts in psychology. The list includes an extremely wide array of terms; because the aim here was to compare major psychological processes and phenomena to inner speech related constructs, numerous non-pertinent categories of terms listed in the glossary had to be discarded. These were: effects (e.g., serial position effect), research designs (e.g., A-B-A design), psychology areas (e.g., comparative psychology), brain structures (e.g., hippocampus) and events (e.g., action potential), basic perceptual phenomena (e.g., absolute threshold), medical conditions (e.g., AIDS), mathematical formulas and procedures (e.g., algorithm), general disorders (e.g., psychotic disorders), general coping mechanisms (e.g., anticipatory coping), general theories (e.g., attribution theory), perceptual qualities (e.g., brightness), psychological tests (e.g., Thematic Apperception Test), general principles (e.g., classical conditioning), general terms (e.g., behavior), methodological issues (e.g., confounding variable), and psychotherapeutic techniques (e.g., placebo therapy). To avoid redundancy, specific cases of a more general process or phenomenon were eliminated; to illustrate, “heuristics” was retained while “availability heuristic”, “anchoring heuristic”, “representativeness heuristic”, and “simulation heuristic” were discarded. A final list of 105 words was selected from the original Glossary (see Table 2 in the Results section below).

PsycINFO was used as a database to perform the citation search. PsycINFO is maintained by the APA; it contains nearly 2.3 million citations of scholarly journal articles, book chapters, books, and dissertations in psychology dating as far back as the 1800s. Ninety seven percent of the covered material is peer-reviewed and includes international material selected from more than 2100 periodicals in more than 25 languages. An advanced search was conducted for each term listed in Table 2 using the following limits: (1) find term in title; (2) from 1900 to 2009; (3) publication type: peer reviewed journal articles; (4) population group: humans; (5) age groups, intended audience, methodology, document type, book type, and classification codes: all; (6) exclude dissertations.

 

Results

Table 2 presents the terms searched in the titles of peer-reviewed journal articles using PsycINFO (left column) and the number of citations obtained in ascending order (right column). The words “conservation” (821 citations) and “resistance” (2115 citations) yielded many results not directly related to Piaget’s theory (for conservation—e.g., wildlife, energy) and Freud’s theory (for resistance—e.g., to insuline or extinction) and were thus discarded. 103 terms were thus retained from the original APA Glossary list.

 

Table 2. Citation frequencies obtained from PsycINFO in peer-reviewed journal articles for

(1) inner speech and related terms, and (2) other key psychological concepts and phenomena.

 

The average citation frequency for all the Glossary terms was 1719; by comparison, the terms “inner speech”, “private speech”, “self-statement”, and “self-talk” were cited 52, 69, 80, and 84 times, respectively. 84.5% of all terms were cited more often than inner speech, 80.6% more often than private speech, and 79.6% more often than both self-talk and self-statement. Sixteen terms were cited less often than inner speech, 20 less often than private speech, and 21 less often than both self-talk and self-statement; 87 terms were cited more often than inner speech, 83 more often than private speech, and 82 more often than both self-talk and self-statement. Remarkably, imagery, the visual counterpart of inner speech, was cited 2970 times while inner speech was cited 52 times.

Figure 1 below compares citation frequencies for 19 terms selected form the list offered in Table 2. These terms were chosen for their high degree of affinity with inner speech in that they may engage or underlie inner speech activity (e.g., short-term memory, self-awareness) and/or are closely related or theoretically comparable to inner speech (e.g., again imagery). Note that inner speech represents the second least frequently cited term (after controlled processes) on the chart.

 

Figure 1. Comparison of PsycINFO citation frequencies for 19 terms selected form the APA Glossary.

 

 

Discussion and Conclusion

Study 1 strongly suggests that inner speech is under-cited in the Introductory Psychology literature; when it is mentioned, coverage is superficial at best. This constitutes a surprising observation given the central role inner speech plays in consciousness and cognition. Future studies could explore if this inder-citation holds for Introductory Psychology textbooks, Developmental Psychology textbooks, Cognition texbooks, Psychotherapy textbooks, and so forth. The present author has already been conducting informal versions of such studies with Social Cognition textbooks in recent years, which so far have yielded results that are highly consistent with those obtained in Study 1 presented here.

Study 2 shows that compared to other important psychological concepts and phenomena, inner speech and related terms are much less frequently cited in peer-reviewed journal articles. Although speculative, one can tentatively argue that the low citation frequencies for inner speech are indicative of relatively poor research output. This is not to say that inner speech has not generated its share of research. To illustrate, Vygotsky’s (1943/1962) original ideas about private speech development stimulated numerous attempts at testing these hypotheses (e.g., Kohlberg et al., 1968); this line of research has recently re-emerged (e.g., Winsler et al., 2000). Sophisticated brain-imaging techniques have motivated the publication of quite a few empirical articles that now largely support the explanation of auditory verbal hallucinations in schizophrenic patients in terms of inner speech monitoring deficits (e.g., Shergill et al. 2003). Morever, dysfunctional self-talk and self-statement modification certainly represent reasonably rich research areas (e.g., Meichenbaum & Goodman, 1971). Yet the fact remains that in Study 2 inner speech and related terms produced much fewer citations in PsychINFO than for many other psychological concepts from the APA Glossary, suggesting that inner speech has been neglected compared to other research areas.

Why would inner speech tend to be ignored in the literature and even possibly neglected as a research topic? Although one is inclined to overlook unimportant things, most psychologists would concur that inner speech does represent a central phenomenon and thus would reject the claim that there has been a tendency to ignore it because it is trivial. Rather, one might argue that it is precisely because inner speech is so central to our mental life that we take it for granted—and hence are predisposed to overlook it—a tendency that ultimately manifests itself as under-citation and lack of research biases.

As indicated in introduction, Kinsbourne (2000) notes that inner speech represents a neglected phenomenon at Millenium’s end; one can only hope that this state of affairs will not perpetuate itself in the present Millenium as well.

 

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Author Note

 

 

I would like to thank Naomi Grant and Tony Chaston for their helpful editorial comments on previous versions of this paper. Requests for reprint should be sent to Alain Morin, Department of Psychology, Mount Royal College, 4825 Mount Royal Gate S.W., Calgary, Alberta, Canada T3E 6K6. E-mail: amorin@mtroyal.ca