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Purpose: In the current study, the author investigated the developmental course of phonetic imitation in childhood, and further evaluated existing accounts of phonetic imitation. Method: Sixteen preschoolers, 15 third graders, and 18 college students participated in the current study. An experiment with a modified imitation paradigm with a picture-naming task was conducted, in which participants' voice-onset time (VOT) was compared before and after they were exposed to target speech with artificially increased VOT. Results: Extended VOT in the target speech was imitated by preschoolers and 3rd graders as well as adults, confirming previous findings in phonetic imitation. Furthermore, an age effect of phonetic imitation was observed; namely, children showed greater imitation than adults, whereas the degree of imitation was comparable between preschoolers and 3rd graders. No significant effect of gender or word specificity was observed. Conclusions: Young children imitated fine phonetic details of the target speech, and greater degree of phonetic imitation was observed in children compared to adults. These findings suggest that the degree of phonetic imitation negatively correlates with phonological development., Imitation plays a crucial role in the development of cognitive and social behavior of humans, and it is one of the basic mechanisms governing language acquisition. In addition to well-attested [...]

Offering- and organization-level attributes that affect imitation of innovative products in the professional services industry are examined. Results indicate that the organization-level attributes of innovators increase imitation while offereing-level attributes lower imitation. The interaction between these attributes is also analyzed.

Decades of research in social psychology have captured the surprising ability of people to "read" one another. In contexts as different as evaluating classroom teachers, selecting job applicants or foretelling [...]

Evolutionary game dynamics describe not only frequency-dependent genetic evolution, but also cultural evolution in humans. In this context, successful strategies spread by imitation. It has been shown that the details of strategy update rules can have a crucial impact on evolutionary dynamics in theoretical models and, for example, can significantly alter the level of cooperation in social dilemmas. What kind of strategy update rules can describe imitation dynamics in humans? Here, we present a way to measure such strategy update rules in a behavioral experiment We use a setting in which individuals are virtually arranged on a spatial lattice. This produces a large number of different strategic situations from which we can assess strategy updating. Most importantly, spontaneous strategy changes corresponding to mutations or exploration behavior are more frequent than assumed in many models. Our experimental approach to measure properties of the update mechanisms used in theoretical models will be useful for mathematical models of cultural evolution. update mechanisms | cooperation | finite populations | structured populations www.pnas.org/cgi/doi/10.1073/pnas.0912515107

Macaques, like humans, rapidly orient their attention in the direction other individuals are looking. Both cortical and subcortical pathways have been proposed as neural mediators of social gaze following, but neither pathway has been characterized electrophysiologically in behaving animals. To address this gap, we recorded the activity of single neurons in the lateral intraparietal area (LIP) of rhesus macaques to determine whether and how this area might contribute to gaze following. A subset of LIP neurons mirrored observed attention by firing both when the subject looked in the preferred direction of the neuron, and when observed monkeys looked in the preferred direction of the neuron, despite the irrelevance of the monkey images to the task. Importantly, the timing of these modulations matched the time course of gaze-following behavior. A second population of neurons was suppressed by social gaze cues, possibly subserving task demands by maintaining fixation on the observed face. These observations suggest that LIP contributes to sharing of observed attention and link mirror representations in parietal cortex to a well studied imitative behavior. gaze following | imitation | joint attention | mirror neurons | shared attention

Previous research indicates that imitation of gestures in preschool children is goal-directed. A goal may be a salient feature from a presented movement: that goal may be imitated correctly, but other features were ignored, resulting in observable errors. Objects (e.g., a dot on the table) can become the most salient features and presence or absence of objects influences imitation responses. Imitation responses were examined under conditions in which objects could not be used directly as the most salient feature. 60 children (M age = 5:6) were assigned to Gestural, Dot, No-dot, and Un-dot conditions, and they were asked to imitate 20 movements. The type of presented movement and the occurrence of correct, mirror, and error responses were examined. Responses in the Un-dot condition were similar to those in the Dot condition. Error responses in the Un-dot condition were related to age. Children may extract a more abstract feature in a context without visible objects. This ability is associated with a cognitive mechanism developed in preschool years.

The spread of contentious practices from activism-prone to mainstream firms is studied. This spread is triggered by the adoption of such practices by firms known to resist activism. This effect is similar to that brought by former US President Richard Nixon's visit to China, which led other countries to open relations with that country.

Imitation, deliberation, and mindreading are characteristically human sociocognitive skills. Research on imitation and its role in social cognition is flourishing across various disciplines. Imitation is surveyed in this target article under headings of behavior, subpersonal mechanisms, and functions of imitation. A model is then advanced within which many of the developments surveyed can be located and explained. The shared circuits model (SCM) explains how imitation, deliberation, and mindreading can be enabled by subpersonaJ mechanisms of control, mirroring, and simulation. It is cast at a middle, functional level of description, that is, between the level of neural implementation and the level of conscious perceptions and intentional actions. The SCM connects shared informational dynamics for perception and action with shared informational dynamics for self and other, while also showing how the action/perception, self/other, and actual/possible distinctions can be overlaid on these shared informational dynamics. It avoids the common conception of perception and action as separate and peripheral to central cognition. Rather, it contributes to the situated cognition movement by showing how mechanisms for perceiving action can be built on those for active perception. The SCM is developed heuristically, in five layers that can be combined in various ways to flame specific ontogenetic or phylogenetic hypotheses. The starting point is dynamic online motor control, whereby an organism is closely attuned to its embedding environment through sensorimotor feedback. Onto this are layered functions of prediction and simulation of feedback, mirroring, simulation of mirroring, monitored inhibition of motor output, and monitored simulation of input. Finally, monitored simulation of input speeifying possible actions plus inhibited mirroring of such possible actions can generate information about the possible as opposed to actual instrumental actions of others, and the possible causes and effects of such possible actions, thereby enabling strategie social deliberation. Multiple instances of such shared circuits structures could be linked into a network permitting decomposition and recombination of elements, enabling flexible control, imitative learning, understanding of other agents, and instrumental and strategic deliberation. While more advanced forms of social cognition, which require tracking multiple others and their multiple possible actions, may depend on interpretative theorizing or language, the SCM shows how layered mechanisms of control, mirroring, and simulation can enable distinctively human cognitive capacities for imitation, deliberation, and mindreading. Keywords: action; active perception; control; embodied cognition; imitation; instrumental deliberation; isomorphism; mindreading; mirroring; mirror neurons; shared circuits; simulation; social cognition

A study on blind imitation behavior of pigeons based on food reward experiment is presented

The authors argue that imitation is a flexible and adaptive learning mechanism in that children do not always reproduce all of the details they can from a demonstration. Instead, they vary their replications depending on their interpretation of the situation. Specifically, the authors propose that when children do not understand the overall reason for a model's behavior, they will be more likely to imitate precisely. By copying conservatively in these situations, children may have a good chance of reproducing the action of the model correctly. In contrast, when the reason for an action is clear, children will be more likely to deviate from the manners and flourishes of the model and use their own means to complete the action. Keywords: imitation, goals, children, social learning

Since Thorstein Veblen, perennial themes in institutionalist writings have included the role of imitation (or emulation) and the tension between inertia (or conservatism) and innovation in individual and organizational behavior. [...]

In a series of studies the Self Salience Model of other-to-self effects is tested. This model posits that self-construal salience is an important determinant of whether other-to-self effects follow the principles of self-enhancement, imitation, or complementarity. Participants imagined interactions (Studies 1 and 2) or were confronted (Studies 3 to 5) with dominant, submissive, agreeable, or quarrelsome person targets. Findings support the prediction that subsequent self-evaluations (Studies 1 to 3) and behaviors (Studies 4 and 5) follow the principles of self-enhancement when the personal self is activated (contrast away from undesirable targets, assimilation toward desirable targets); the principles of complementarity when the relational self is activated (contrast on the dominant--submissive dimension, assimilation on the agreeable--quarrelsome dimension); and the principles of imitation when the collective self is activated (assimilation regardless of desirability or dimension). Keywords: self-enhancement, imitation, complementarity, self-construal, social comparison

Perceiving other people's behaviors activates imitative motor plans in the perceiver, but there is disagreement as to the function of this activation. In contrast to other recent proposals (e.g., that it subserves overt imitation, identification and understanding of actions, or working memory), here it is argued that imitative motor activation feeds back into the perceptual processing of conspecifies' behaviors, generating top-down expectations and predictions of the unfolding action. Furthermore. This account incorporates recent ideas about emulators in the brain mental simulations that run in parallel to the external events they simulate to provide a mechanism by which motoric involvement could contribute to perception. Evidence from a variety of literatures is brought to bear to support this account of perceiving human body movement. Keywords: imitation, mirror neurons, prediction, emulator, representational momentum

An investigation into the possible relationship between imitation, intersubjectivity, and pretherapy is done. Brief explanations on pretherapeutic reflections engage basic, innate potentialities in infants and others, making it possible to explain the successful application of pretherapy from a developmental perspective.

Byline: Justin H. G. Williams (1), Andrew Whiten (2), Tulika Singh (3) Keywords: Imitation; gesture; action; autism; emulation; 'mirror neurons' Abstract: Imitative deficits have been associated with autistic spectrum disorder (ASD) for many years, most recently through more robust methodologies. A fresh, systematic review of the significance, characteristics, and underlying mechanism of the association is therefore warranted. From 121 candidates, we focused on 21 well-controlled studies involving 281 cases of ASD. Overall, children with ASD performed worse on imitative tasks (Combined Logit p value &lt .00005). The emerging picture is of delayed development in imitation, implicating a deficit in mapping neural codings for actions between sensory and motor modalities, rather than in motivation or executive function. We hypothesise that ASD is characterised by abnormal development of these mappings, such that they are biased towards object-oriented tasks at the expense of those required for action imitation per se. Author Affiliation: (1) Department of Child Health, University of Aberdeen, Medical School, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK (2) School of Psychology, University of St.Andrews, St.Andrews, Scotland, UK (3) Torbay Hospital, Torbay Article History: Registration Date: 18/10/2004

This essay examines the ways in which imitation, as a concept and as a practice, was caught up in the nineteenth century's racial politics. Theoretically, it argues that the interpretation of mimesis labels the imitator and either sustains or reconstitutes power relations within the context of mimetic performance. Historically, the essay contends that during the nineteenth century, and especially after the Civil War, black imitation threatened the dominant systems of white power. European Americans interpreted black mimesis as a primitive instinct, the sign of an inferior 'other.' Conversely, African Americans used imitation to exercise their liberty and pursue civil rights. Frederick Douglass viewed imitation as a progressive force in public life, and his conceptualization represents an alternative to the reductive construct that existed at the beginning of the twentieth century and continues today. Key words: imitation, mimesis, African American political rhetoric, Reconstruction, race

To explore whether imitation of novel behaviors might serve as a lexical acquisition strategy for some infants, relations between infants' early spontaneous reproduction of novel and of familiar words and [...]

In the present experiments, the 2-action method was used to determine whether pigeons could learn to imitate a conditional discrimination. Demonstrator pigeons (Columba livia) stepped on a treadle in the presence of 1 light and pecked at the treadle in the presence of another light. Demonstration did not seem to affect acquisition of the conditional discrimination (Experiment 1) but did facilitate its reversal of the conditional discrimination (Experiments 2 and 3). The results suggest that pigeons are not only able to learn a specific behavior by observing another pigeon, but they can also learn under which circumstances to perform that behavior. The results have implications for proposed mechanisms of imitation in animals.

The purpose of this study was to examine college-age males' ability to produce the acoustic properties of the normally aging voice when reading. The 17 subjects (M age=21.13 yr., SD=1.0) selected for this study were undergraduates who were placed into a single group. The procedure involved recording the subjects while reading The Rainbow Passage aloud. The first reading was in the subject's natural speaking voice. During the second reading, the reader imitated the voice of a normally aging 70-yr.-old man. Fundamental frequency and temporal measures were analyzed for each voice sample. Mean scores for each measure werecompared for the natural speaking-voice production and the production when imitatihg the voice of a normally aging 70-yr.-old man. Analysis showed that temporal measures appear to have the most significant influence on subjects' production when imitating the normally aging voice as seen in the overall increase in all temporal measures.

This article discusses the influence of sociologist Gudmundur Finnbogason. The author examines Finnbogason's research on the significance of imitation in understanding the minds of others, in which Finnbogason argues that imitating someone else is essential to comprehending their mentality

The purpose of the study was to investigate what kind of factors determine the degree of difficulty for chimpanzees (Pan troglodytes) when they imitate actions. Five adult chimpanzees were instructed to perform 48 arbitrary manipulatory actions consisting of different bodily motor patterns and object directionality. Results showed that actions in which an object is directed toward another external location (another object and one's own body) were easier to perform than those that involved manipulating a single object alone. Actions involving unfamiliar motor patterns were more difficult to perform than those involving familiar motor patterns that were already present in the subject's repertoire. Error responses were characterized as perseverative repetition of previously instructed actions. These findings suggest that chimpanzees find the directionality of manipulated objects a more salient cue than details of the demonstrator's body movements performing the manipulation.

Imitation was studied experimentally by allowing chimpanzees (Pan troglodytes) to observe alternative patterns of actions for opening a specially designed 'artificial fruit.' Like problematic foods primates deal with naturally, with the test fruit several defenses had to be removed to gain access to an edible core, but the sequential order and method of defense removal could be systematically varied. Each subject repeatedly observed 1 of 2 alternative techniques for removing each defense and 1 of 2 alternative sequential patterns of defense removal. Imitation of sequential organization emerged after repeated cycles of demonstration and attempts at opening the fruit. Imitation in chimpanzees may thus have some power to produce cultural convergence, counter to the supposition that individual learning processes corrupt copied actions. Imitation of sequential organization was accompanied by imitation of some aspects of the techniques that made up the sequence.

A male zebra finch, Taeniopygia guttata, kept with its father until adulthood develops an imitation of its father's song motif. We report here that the completeness of this imitation was sensitive to the social or auditory context in which the bird grew up: the greater the number of male siblings in a clutch, the shorter the mean duration of the song motif and the fewer the mean number of song notes imitated from the father; the latter shortfall was not compensated by other, improvised notes. We call this effect fraternal inhibition. Fraternal inhibition was avoided by members of a clutch that developed the song first. To our surprise, this role commonly fell to one of the younger birds in the clutch. Early song learning may influence fitness since individuals that produced the most complete imitations also tended to induce more egg laying.

A sample of 80 economics and econometrics majors from a university participated in an experiment to determine which type of learning can be experimentally observed. The three types of learning, which include learning from experience, learning by imitation, and learning from secondhand experience, were compared against the ideal Bayesian. Results supported the theory that individuals learn from their own experience but not as much as the model Bayesian would.

Drawing on neoinstitutional and learning theories, we distinguish three distinct modes of selective interorganizational imitation: frequency imitation (copying very common practices), trait imitation (copying practices of other organizations with certain features), and outcome imitation (imitation based on a practice's apparent impact on others). We investigate whether these imitation modes occur independently and are affected by outcome salience and contextual uncertainty in the context of an important decision: which investment banker to use as adviser on an acquisition. Results of testing hypotheses on 539 acquisitions that occurred in 1988-1993 show that all three imitation modes occur independently, but only highly salient outcomes sustain outcome imitation. Uncertainty enhances frequency imitation, but only some trait and outcome imitation. The results highlight the possible joint operation of social and technical indicators in imitation, illuminate factors that moderate vicarious learning processes, and show asymmetries between learning from success and failure.(*), Many early theories emphasizing the importance of organizational context portrayed organizational environments as broad, static entities, characterized by stable properties such as turbulence or munificence (e.g., Lawrence and Lorsch, 1967). [...]

Four multimethod studies probed the hypothesis, derived from the Zajonc-Markus motor theory of emotion, that facial recognition is enhanced by imitation of the faces. In all studies, participants were (a) randomly assigned to imitate or to concentrate on a set of faces presented on slides; (b) covertly videotaped, or measured for facial electromyographic responses, to assess facial motor responsiveness; (c) asked to recognize faces previously seen from a larger set; and (d) asked to complete individual difference measures relevant to imitation or memory. The major dependent variable was the percentage of faces accurately recognized. Across variations in procedure, persons who initially imitated faces later recognized fewer faces than did persons in various control conditions. No evidence was found for individual difference moderators of this general conclusion. Results call into question the adequacy of the Zajonc-Markus motoric theory explanation of memory for faces.

The study of imitative learning in animals has suffered from the presence of a number of confounding motivational and attentional factors (e.g., social facilitation and stimulus enhancement). The two-action method avoids these problems by exposing observers to demonstrators performing a response (e.g., operating a treadle) using 1 of 2 distinctive topographies (e.g., by pecking or by stepping). Japanese quail (Coturnix japonica) observers exposed to conspecific demonstrators showed a high correlation between the topography of the response they observed and the response they performed. These data provide strong evidence for the existence of true imitative learning in an active, precocious bird under conditions that control for alternative accounts.

Fourteen juvenile and adult orangutans and 24 3- and 4-year-old children participated in 4 studies on imitative learning in a problem-solving situation. In all studies a simple to operate apparatus was used, but its internal mechanism was hidden from subjects to prevent individual learning. In the 1st study, orangutans observed a human demonstrator perform 1 of 4 actions on the apparatus and obtain a reward; they subsequently showed no signs of imitative learning. Similar results were obtained in a 2nd study in which orangutan demonstrators were used. Similar results were also obtained in a 3rd study in which a human encouraged imitation from an orangutan that had previously been taught to mimic arbitrary human actions. In a 4th study, human 3- and 4-year-old children learned the task by means of imitation.

We discuss selectivity in great ape imitation, on the basis of an observational study of spontaneous imitation in free-ranging rehabilitant orangutans (Pongo pygmaeus). Research on great ape imitation has neglected selectivity, although comparative evidence suggests it may be important. We observed orangutans in central Indonesian Borneo and assessed patterns in the models and actions they spontaneously imitated. The patterns we found resembled those reported in humans. Orangutans preferred models with whom they had positive affective relationships (e.g., important caregiver or older sibling) and actions that reflected their current competence, were receptively familiar, and were relevant to tasks that faced them. Both developmental and individual variability were found. We discuss the probable functions of imitation for great apes and the role of selectivity in directing it. We also make suggestions for more effective elicitation of imitation.

The encouragement of imitation may be a wise strategy in industries where a positive network externality exists. In such industries, the presence of a network externality rewards imitation because consumers in these industries tend to value a product more when more consumers use the product. Examples of such industries are those involving networks such as telephones and railroads and those requiring the use of other products for their operation such as computer software and video casette recorders. A model that can be used by innovators in industries where a positive network externality is present is described. The model allows innovators to assess the key factors that determine when imitation or 'cloning' may be advisable. As a rule, the model advises a cloning strategy if the benefits obtained from a bigger user base outweigh the sales losses that accrue due to the presence of clones.

Each of two bottlenose dolphins, Tursiops truncatus, was trained to mimic a set of behaviors on command. They were tested on transfer of the mimic command to a set of familiar behaviors which they had not previously been commanded to mimic. They were similarly tested on two novel behaviors. One dolphin demonstrated complete mimicry of 5 of 11 familiar behaviors; the other dolphin mimicked 1 of 9 behaviors. None of the mimicked behaviors was exhibited to an inappropriate model, suggesting that performance was not due to chance. Neither dolphin imitated the novel behaviors.

This article considers the evidence for an imitative deficit in autism and for the possible role of deficiencies in the representation of actions. An argument is developed for the claim that the imitation problem is diagnostic of a basic information-processing rather than a social dysfunction. Reviews are offered of the empirical literature on gestural imitation in autism (and other developmental disorders) and the more anecdotal evidence for problems in the domain of action development in autism. An account that may help to integrate these areas is suggested, as are directions for future research.

Rats that observed demonstrators pushing joysticks in a particular direction were likelier to then push it in the same direction only if the demonstrator received food and a tone was sounded as a reward. A 5-sec delay between the act and the reward did not affect this imitation, nor did intermittent rather than continuous rewards. However, observers that saw demonstrators rewarded with tone or food alone were not likely to select the chosen direction for their own pushes.

We made an observational study of spontaneous imitation in orangutans (Pongo pygmaeus). Previous studies may have underestimated great apes' imitative capacities by studying subjects under inhibiting conditions. We used subjects living in enriched environments, namely, rehabilitation. We collected a sample of spontaneous imitations and analyzed the most complex incidents for the likelihood that true imitation, learning new actions by observing rather than by doing, was involved in their acquisition. From 395 hr of observation and other reports on 26 orangutans, we identified 354 incidents of imitation. Of these, 54 complex incidents were difficult to explain by forms of imitation based on associative processes grounded in experiential learning alone; they were, however, congruent with acquisition processes that include true imitation. These findings suggest that orangutans may be capable of true imitation and point to critical eliciting factors.

The term 'imitation' is generally used by ethologists to cover interactions between conspecifics in which an unusual or novel behavioral repertoire exhibited by an animal is emitted by an observing conspecific. The major explanatory classes created to explain this phenomenon will be briefly outlined in the current review. In particular, attention shall be drawn to the debate surrounding the existence of 'true imitation' in animals, which is generally regarded as the ability to imitate response topography in a reflective' and 'goal orientated' manner. This paper proposes that current procedural difficulties found in the field are a product of a number of implicit theoretical assumptions and trends in methodological design. In particular, the importance of discriminating between functional and topographical aspects of behavior is highlighted. Finally, the employment of a behavior synthesis methodology to facilitate the demonstration of true imitation in animals is presented as a feasible alternative to current approaches in this field., Diverse, unusual, and often highly complex behaviors are emitted by individual organisms across the animal kingdom. One feature common to most behavioral patterns is that the same behaviors tend to [...]

A study was conducted to analyze how a bounded rational person should learn from the experience of a limited number of other individuals who face the same decision. The double sampling method was utilized, in which an individual may learn between making choices from the experience of two other randomly chosen persons. Results indicated that the formalization of performance correlates with the same class of so-called 'strictly improving' behavioral rules.

A study was conducted to investigate how waiting to imitate a product affects the performance of the imitator compared to the innovator. It is argued that the increasing availability of information on the innovator's product increases the imitator's returns to waiting. It is concluded that imitation timing reflects the uncertainty inherent in imitation efforts.

An evolutionary cladogram linking nearly one hundred forms of learning and showing the paths through which they evolved are reviewed. The findings indicate that cladogram involved at least eight new process including abstract concept formation, and percussive mimicry.

Two experiments were conducted to investigate whether mimicry leads to pro-social behavior. The results revealed that, compared to the baseline, mimicry leads to larger tips, and demonstrate that mimicry can be advantageous for the imitator because it can make people more generous.

With regard to prey motion, the evolution of mimicry has been investigated in three areas: 1) locomotor mimicry, 2) anti-apostatic selection, and 3) escape mimicry. Locomotor mimicry is the similarity in motion of two distantly-related prey species. Because of evolutionary convergence in key morphological features that are relevant to flight, convergence in the flight behavior of distasteful, mimetic passion-vine butterflies in the genus Heliconius was predicted. Applying a methodology developed in C.P. Ellingtonis laboratory, I present evidence that mimetic Heliconius are more similar in wingbeat frequency and the degree of asymmetry in the wing motion than they are to their sister species. Anti-apostatic selection, or selection against odd individuals, may be the selective force for behavioral similarity among M,Ilerian mimics. Prey motion increases selection against odd individuals when prey are at high densities, and perhaps when the prey are M,Ilerian mimics. Ultimately, the behaviors of the different mimetic morphs should converge on that behavior which minimizes the energetic cost of flight. Applying Ellingtonis aerodynamic models, I estimated the energetic cost of each mimetic morphis flight behavior in order to qualitatively predict the difference in height of each fitness peak and the direction of convergent selection. Following adjustments for body mass, mimetic H. melpomene and H. erato required more aerodynamic power than H. cydno and H. sapho. This difference was attributed to the slower flight speeds and higher wingbeat frequencies of H. melpomene and H. erato. From morphology, locomotor mimicry with important limitations is also predicted to occur in palatable species that appear like distasteful models (Batesian mimics), and among palatable species that are color mimetic due to unprofitable prey (or escape) mimicry.

In this study, the authors investigated the understanding of other's actions in 5 adult chimpanzees (Pan troglodytes). A human demonstrated an attempt to open different containers. Each container required a different motor pattern to open it. Along with the container, a 2nd object was made available. After a free play period in which the chimpanzees' natural behaviors toward the objects were recorded, the authors tested the following 2 phases: The demonstrator (a) tried but failed to open and (b) opened the container successfully, with 1 of 2 alternative strategies, either using an 'irrelevant tool' or by hand. The chimpanzees did not reproduce the demonstrator's motor patterns precisely but did reproduce the demonstrated strategies in both phases. These results suggest that chimpanzees anticipate the intentions of others by perceiving the directionality and causality of object(s) as available cues.

The purpose of the present study was to investigate the impact of utterance length and syntactic complexity on the speech motor stability of adults who stutter. Lower lip movement was recorded from 8 adults who stutter and 8 normally fluent controls. They produced a target phrase in isolation (baseline condition) and the same phrase embedded in utterances of increased length and/or increased syntactic complexity. The spatiotemporal index (STI) was used to quantify the stability of lower lip movements across multiple repetitions of the target phrase. Results indicated: (a) Adults who stutter demonstrated higher overall STI values than normally fluent adults across all experimental conditions, indicating decreased speech motor stability; (b) the speech motor stability of normally fluent adults was not affected by increasing syntactic complexity, but the speech motor stability of adults who stutter decreased when the stimuli were more complex; (c) increasing the length of the target utterance (without increasing syntactic complexity) did not affect the speech motor stability of either speaker group. These results indicate that language formulation processes may affect speech production processes and that the speech motor systems of adults who stutter may be especially susceptible to the linguistic demands required to produce a more complex utterance. The present findings, therefore, support the hypothesis that linguistic complexity is one factor that contributes to the disruptions of speech motor stability characteristic of stuttering. KEY WORDS: stuttering, fluency, linguistic complexity, kinematics, speech motor control, For the past 50 years, researchers have attempted to discover the relationship between linguistic variables and overt stuttering behaviors. Early experiments focused primarily on the properties of stuttered words. For [...]