The coordination of physiological processes between parents and infants is thought to support beh... more The coordination of physiological processes between parents and infants is thought to support behaviors critical for infant adaptation, but we know little about parent-child physiological coregulation during the preschool years. The present study examined whether time-varying changes in parent and child respiratory sinus arrhythmia (RSA) exhibited coregulation (acrossperson dynamics) accounting for individual differences in parent and child RSA, and whether there were differences in these parasympathetic processes by children's externalizing problems.
A number of models for estimating the coecients of dynamical systems have been proposed. One is t... more A number of models for estimating the coecients of dynamical systems have been proposed. One is the exact discrete model, another is the latent dierences
Here we present an overview of a system we are developing for animat- ing faces using appearance ... more Here we present an overview of a system we are developing for animat- ing faces using appearance models. To facilitate more widespread use of animated characters, we are interested in developing techniques that: 1) re- quire only easy to use and inexpensive data capture equipment, 2) are three- dimensional allowing virtual characters to be animated, 3) allow a range of
When people speak with one another they tend to adapt their head move- ments and facial expressio... more When people speak with one another they tend to adapt their head move- ments and facial expressions in response to each others' head movements and facial expressions. We present an experiment in which confederates' head movements and facial expressions were motion tracked during videoconfer- ence conversations, an avatar face was reconstructed in real time, and naive participants spoke with the
2009 10th Workshop on Image Analysis for Multimedia Interactive Services, 2009
Small digital video cameras have become increasingly common, appearing on portable consumer devic... more Small digital video cameras have become increasingly common, appearing on portable consumer devices such as cellular phones. The widespread use of video-conferencing, however, is limited in part by the lack of bandwidth available on such devices. Also, videoconferencing can produce feelings of discomfort in conversants due to a lack of co-presence. Current techniques to increase co-presence are not practical in the consumer market due to the costly and elaborate equipment required (such as stereoscopic displays and multicamera arrays).
Social psychological and personality science, 2014
A classical twin study was used to estimate the magnitude of genetic and environmental influences... more A classical twin study was used to estimate the magnitude of genetic and environmental influences on four measurements of within-person variability: dominance flux, warmth flux, spin and pulse. Flux refers to the variability of an individual's interpersonal dominance and warmth. Spin measures changes in the tone of interpersonal styles and pulse measures changes in the intensity of interpersonal styles. Daily reports of interpersonal styles were collected from 494 same-sex female twins (142 monozygotic pairs and 105 dizygotic pairs) over 45 days. For dominance flux, warmth flux, and spin, genetic effects accounted for a larger proportion of variance (37%, 24%, and 30%, respectively) than shared environmental effects (14%, 13%, 0%, respectively), with the remaining variance due to the non-shared environment (62%, 50%, 70% respectively). Pulse appeared to be primarily influenced by the non-shared environment, although conclusions about the contribution of familial influences were ...
Clinical psychological science : a journal of the Association for Psychological Science, 2014
Changes in ovarian hormones predict changes in emotional eating across the menstrual cycle. Howev... more Changes in ovarian hormones predict changes in emotional eating across the menstrual cycle. However, prior studies have not examined whether the nature of associations varies across dysregulated eating severity. The current study determined whether the strength and/or nature of hormone/dysregulated eating associations differ based on the presence of clinically diagnosed binge episodes (BEs). Participants included 28 women with BEs and 417 women without BEs who provided salivary hormone samples, ratings of emotional eating, and BE frequency for 45 days. Results revealed stronger associations between dysregulated eating and ovarian hormones in women with BEs as compared to women without BEs. The nature of associations also differed, as progesterone moderated the effects of lower estradiol levels on dysregulated eating in women with BEs only. Although hormone/dysregulated eating associations are present across the spectrum of pathology, the nature of associations may vary in ways that ...
In the present paper we investigate weekly fluctuations in the working memory capacity (WMC) asse... more In the present paper we investigate weekly fluctuations in the working memory capacity (WMC) assessed over a period of 2 years. We use dynamical system analysis, specifically a second order linear differential equation, to model weekly variability in WMC in a sample of 112 9th graders. In our longitudinal data we use a B-spline imputation method to deal with missing data. The results show a significant negative frequency parameter in the data, indicating a cyclical pattern in weekly memory updating performance across time. We use a multilevel modeling approach to capture individual differences in model parameters and find that a higher initial performance level and a slower improvement at the MU task is associated with a slower frequency of oscillation. Additionally, we conduct a simulation study examining the analysis procedure's performance using different numbers of B-spline knots and values of time delay embedding dimensions. Results show that the number of knots in the B-spline imputation influence accuracy more than the number of embedding dimensions.
Objective: Associations between withinperson changes in ovarian hormones and dysregulated eating ... more Objective: Associations between withinperson changes in ovarian hormones and dysregulated eating (binge eating, emotional eating) have been observed across the menstrual cycle. However, studies have not examined moderators that may contribute to differential associations between individuals. We investigated body-weight regulation variables [body mass index (BMI), dietary restraint] that have theoretical relevance by virtue of their associations with both phenotypes.
Prenatal testosterone exposure may be protective against disordered eating. However, prior studie... more Prenatal testosterone exposure may be protective against disordered eating. However, prior studies have produced mixed results. Developmental differences in prenatal testosterone's protective effects on disordered eating may explain these discrepancies. Indeed, studies have differed in the age of participants assessed, with data supporting prenatal testosterone effects on disordered eating in early adolescent and young adult samples but not in late adolescence. The present studies are the first to investigate age differences in prenatal testosterone's protective effects on disordered eating. Two indirect markers of higher prenatal testosterone were examined: (a) lower finger-length ratios (Study 1: index [2D]/ring [4D] finger [2D:4D]) and (b) lower disordered eating in female s from opposite-sex twin pairs (who are thought to be exposed to higher prenatal testosterone from their male co-twin) relative to female controls (Study 2). Participants were twins from the Michigan State University Twin Registry (Study 1: n = 409; Study 2: n = 1,538) in early adolescence, late adolescence, or young adulthood. Disordered eating was assessed with well-validated questionnaires. Finger-length ratios were measured from hand scans, using electronic computer calipers. Findings were consistent across both studies. Higher prenatal testosterone (lower 2D:4D; females from opposite-sex twin pairs vs. controls) predicted lower disordered eating in early adolescence and young adulthood only. Prenatal testosterone-disordered eating associations were not observed during late adolescence. Results point to the possibility of developmental windows of expression for prenatal testosterone's protective effects on disordered eating and suggest that prior discrepant results may reflect age differences across samples.
Mean-levels of thin-ideal internalization increase during adolescence and pubertal development, b... more Mean-levels of thin-ideal internalization increase during adolescence and pubertal development, but it is unknown whether these phenotypic changes correspond to developmental changes in etiological (i.e., genetic and environmental) risk. Given the limited knowledge on risk for thin-ideal internalization, research is needed to guide the identification of specific types of risk factors during critical developmental periods. The present twin study examined genetic and environmental influences on thin-ideal internalization across adolescent and pubertal development. Participants were 1,064 female twins (ages 8-25 years) from the Michigan State University Twin Registry. Thin-ideal internalization and pubertal development were assessed using self-report questionnaires. Twin moderation models were used to examine if age and/or pubertal development moderate genetic and environmental influences on thin-ideal internalization. Phenotypic analyses indicated significant increases in thin-ideal internalization across age and pubertal development. Twin models suggested no significant differences in etiologic effects across development. Nonshared environmental influences were most important in the etiology of thin-ideal internalization, with genetic, shared environmental, and nonshared environmental accounting for approximately 8%, 15%, and 72%, respectively, of the total variance. Despite mean-level increases in thin-ideal internalization across development, the relative influence of genetic versus environmental risk did not differ significantly across age or pubertal groups. The majority of variance in thin-ideal internalization was accounted for by environmental factors, suggesting that mean-level increases in thin-ideal internalization may reflect increases in the magnitude/strength of environmental risk across this period. Replication is needed, particularly with longitudinal designs that assess thin-ideal internalization across key developmental phases.
Personality Disorders: Theory, Research, and Treatment, 2014
Previous research indicates that borderline personality disorder (BPD) is well conceptualized as ... more Previous research indicates that borderline personality disorder (BPD) is well conceptualized as a dimensional construct that can be represented using normal personality traits. A previous study successfully developed and validated a BPD measure embedded within a normal trait measure, the Minnesota Borderline Personality Disorder Scale (MBPD). The current study performed a further validation of the MBPD by examining its convergent validity, external correlates, and heritability in a sample of 429 female twins. The MBPD correlated strongly with the Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II) screener for BPD and moderately with external correlates. Moreover, the MBPD and SCID-II screener exhibited very similar patterns of external correlations. Additionally, results indicated that the genetic and environmental influences on MBPD overlap with the genetic and environmental influences on the SCID-II screener, which suggests that these scales are measuring the same construct. These data provide further evidence for the construct validity of the MBPD.
A number of models for estimating the coecients of dynamical systems have been proposed. One is t... more A number of models for estimating the coecients of dynamical systems have been proposed. One is the exact discrete model, another is the latent dierences
Structural Equation Modeling: A Multidisciplinary Journal, 2002
Abstract Modern structural equation modeling software programs include user interfaces for the en... more Abstract Modern structural equation modeling software programs include user interfaces for the entry of graphical diagrams as a method for the production of the underlying matrices that are then manipulated in traditional ways to provide parameter estimates and fit statistics. This work presents an algorithm for the solution of the problem in the reverse order: automatically producing a graphical diagram from a matrix formula in such a way that its components are logically and hierarchically arranged. In the process, the individual path components of expected covariance between variables are calculated and feedback loops or so-called nonrecursive paths are recognized and tagged. Possible uses for this algorithm include automatic recognition of regions of structural underidentification in a model and the didactic graphical display of the components of expected covariance between variables. This algorithm relies on the matrix equations of , a general purpose SEM formulation.
OpenMx is free, full-featured, open source, structural equation modeling (SEM) software. OpenMx r... more OpenMx is free, full-featured, open source, structural equation modeling (SEM) software. OpenMx runs within the R statistical programming environment on Windows, Mac OS-X, and Linux computers. The rationale for developing OpenMx is discussed along with the philosophy behind the user interface. The OpenMx data structures are introduced-these novel structures define the user interface framework and provide new opportunities for model specification. Two short example scripts for the specification and fitting of a confirmatory factor model are next presented. We end with an abbreviated list of modeling applications available in OpenMx 1.0 and a discussion of directions for future development.
This paper investigates the precision of parameters estimated from local samples of time dependen... more This paper investigates the precision of parameters estimated from local samples of time dependent functions. We find that time delay embedding, i.e., structuring data prior to analysis by constructing a data matrix of overlapping samples, increases the precision of parameter estimates and in turn statistical power compared to standard independent rows of panel data. We show that the reason for this effect is that the sign of estimation bias depends on the position of a misplaced data point if there is no a priori knowledge about initial conditions of the time dependent function. Hence, we reason that the advantage of time delayed embedding is likely to hold true for a wide variety of functions. We support these conclusions both by mathematical analysis and two simulations. 159 design has the advantage of a large sample of individuals, and thus the standard error of the mean within-person time series coefficient may be small. In this example design, 1,000 observations were made: 5 observations on each of 200 individuals.
The coordination of physiological processes between parents and infants is thought to support beh... more The coordination of physiological processes between parents and infants is thought to support behaviors critical for infant adaptation, but we know little about parent-child physiological coregulation during the preschool years. The present study examined whether time-varying changes in parent and child respiratory sinus arrhythmia (RSA) exhibited coregulation (acrossperson dynamics) accounting for individual differences in parent and child RSA, and whether there were differences in these parasympathetic processes by children's externalizing problems.
A number of models for estimating the coecients of dynamical systems have been proposed. One is t... more A number of models for estimating the coecients of dynamical systems have been proposed. One is the exact discrete model, another is the latent dierences
Here we present an overview of a system we are developing for animat- ing faces using appearance ... more Here we present an overview of a system we are developing for animat- ing faces using appearance models. To facilitate more widespread use of animated characters, we are interested in developing techniques that: 1) re- quire only easy to use and inexpensive data capture equipment, 2) are three- dimensional allowing virtual characters to be animated, 3) allow a range of
When people speak with one another they tend to adapt their head move- ments and facial expressio... more When people speak with one another they tend to adapt their head move- ments and facial expressions in response to each others' head movements and facial expressions. We present an experiment in which confederates' head movements and facial expressions were motion tracked during videoconfer- ence conversations, an avatar face was reconstructed in real time, and naive participants spoke with the
2009 10th Workshop on Image Analysis for Multimedia Interactive Services, 2009
Small digital video cameras have become increasingly common, appearing on portable consumer devic... more Small digital video cameras have become increasingly common, appearing on portable consumer devices such as cellular phones. The widespread use of video-conferencing, however, is limited in part by the lack of bandwidth available on such devices. Also, videoconferencing can produce feelings of discomfort in conversants due to a lack of co-presence. Current techniques to increase co-presence are not practical in the consumer market due to the costly and elaborate equipment required (such as stereoscopic displays and multicamera arrays).
Social psychological and personality science, 2014
A classical twin study was used to estimate the magnitude of genetic and environmental influences... more A classical twin study was used to estimate the magnitude of genetic and environmental influences on four measurements of within-person variability: dominance flux, warmth flux, spin and pulse. Flux refers to the variability of an individual's interpersonal dominance and warmth. Spin measures changes in the tone of interpersonal styles and pulse measures changes in the intensity of interpersonal styles. Daily reports of interpersonal styles were collected from 494 same-sex female twins (142 monozygotic pairs and 105 dizygotic pairs) over 45 days. For dominance flux, warmth flux, and spin, genetic effects accounted for a larger proportion of variance (37%, 24%, and 30%, respectively) than shared environmental effects (14%, 13%, 0%, respectively), with the remaining variance due to the non-shared environment (62%, 50%, 70% respectively). Pulse appeared to be primarily influenced by the non-shared environment, although conclusions about the contribution of familial influences were ...
Clinical psychological science : a journal of the Association for Psychological Science, 2014
Changes in ovarian hormones predict changes in emotional eating across the menstrual cycle. Howev... more Changes in ovarian hormones predict changes in emotional eating across the menstrual cycle. However, prior studies have not examined whether the nature of associations varies across dysregulated eating severity. The current study determined whether the strength and/or nature of hormone/dysregulated eating associations differ based on the presence of clinically diagnosed binge episodes (BEs). Participants included 28 women with BEs and 417 women without BEs who provided salivary hormone samples, ratings of emotional eating, and BE frequency for 45 days. Results revealed stronger associations between dysregulated eating and ovarian hormones in women with BEs as compared to women without BEs. The nature of associations also differed, as progesterone moderated the effects of lower estradiol levels on dysregulated eating in women with BEs only. Although hormone/dysregulated eating associations are present across the spectrum of pathology, the nature of associations may vary in ways that ...
In the present paper we investigate weekly fluctuations in the working memory capacity (WMC) asse... more In the present paper we investigate weekly fluctuations in the working memory capacity (WMC) assessed over a period of 2 years. We use dynamical system analysis, specifically a second order linear differential equation, to model weekly variability in WMC in a sample of 112 9th graders. In our longitudinal data we use a B-spline imputation method to deal with missing data. The results show a significant negative frequency parameter in the data, indicating a cyclical pattern in weekly memory updating performance across time. We use a multilevel modeling approach to capture individual differences in model parameters and find that a higher initial performance level and a slower improvement at the MU task is associated with a slower frequency of oscillation. Additionally, we conduct a simulation study examining the analysis procedure's performance using different numbers of B-spline knots and values of time delay embedding dimensions. Results show that the number of knots in the B-spline imputation influence accuracy more than the number of embedding dimensions.
Objective: Associations between withinperson changes in ovarian hormones and dysregulated eating ... more Objective: Associations between withinperson changes in ovarian hormones and dysregulated eating (binge eating, emotional eating) have been observed across the menstrual cycle. However, studies have not examined moderators that may contribute to differential associations between individuals. We investigated body-weight regulation variables [body mass index (BMI), dietary restraint] that have theoretical relevance by virtue of their associations with both phenotypes.
Prenatal testosterone exposure may be protective against disordered eating. However, prior studie... more Prenatal testosterone exposure may be protective against disordered eating. However, prior studies have produced mixed results. Developmental differences in prenatal testosterone's protective effects on disordered eating may explain these discrepancies. Indeed, studies have differed in the age of participants assessed, with data supporting prenatal testosterone effects on disordered eating in early adolescent and young adult samples but not in late adolescence. The present studies are the first to investigate age differences in prenatal testosterone's protective effects on disordered eating. Two indirect markers of higher prenatal testosterone were examined: (a) lower finger-length ratios (Study 1: index [2D]/ring [4D] finger [2D:4D]) and (b) lower disordered eating in female s from opposite-sex twin pairs (who are thought to be exposed to higher prenatal testosterone from their male co-twin) relative to female controls (Study 2). Participants were twins from the Michigan State University Twin Registry (Study 1: n = 409; Study 2: n = 1,538) in early adolescence, late adolescence, or young adulthood. Disordered eating was assessed with well-validated questionnaires. Finger-length ratios were measured from hand scans, using electronic computer calipers. Findings were consistent across both studies. Higher prenatal testosterone (lower 2D:4D; females from opposite-sex twin pairs vs. controls) predicted lower disordered eating in early adolescence and young adulthood only. Prenatal testosterone-disordered eating associations were not observed during late adolescence. Results point to the possibility of developmental windows of expression for prenatal testosterone's protective effects on disordered eating and suggest that prior discrepant results may reflect age differences across samples.
Mean-levels of thin-ideal internalization increase during adolescence and pubertal development, b... more Mean-levels of thin-ideal internalization increase during adolescence and pubertal development, but it is unknown whether these phenotypic changes correspond to developmental changes in etiological (i.e., genetic and environmental) risk. Given the limited knowledge on risk for thin-ideal internalization, research is needed to guide the identification of specific types of risk factors during critical developmental periods. The present twin study examined genetic and environmental influences on thin-ideal internalization across adolescent and pubertal development. Participants were 1,064 female twins (ages 8-25 years) from the Michigan State University Twin Registry. Thin-ideal internalization and pubertal development were assessed using self-report questionnaires. Twin moderation models were used to examine if age and/or pubertal development moderate genetic and environmental influences on thin-ideal internalization. Phenotypic analyses indicated significant increases in thin-ideal internalization across age and pubertal development. Twin models suggested no significant differences in etiologic effects across development. Nonshared environmental influences were most important in the etiology of thin-ideal internalization, with genetic, shared environmental, and nonshared environmental accounting for approximately 8%, 15%, and 72%, respectively, of the total variance. Despite mean-level increases in thin-ideal internalization across development, the relative influence of genetic versus environmental risk did not differ significantly across age or pubertal groups. The majority of variance in thin-ideal internalization was accounted for by environmental factors, suggesting that mean-level increases in thin-ideal internalization may reflect increases in the magnitude/strength of environmental risk across this period. Replication is needed, particularly with longitudinal designs that assess thin-ideal internalization across key developmental phases.
Personality Disorders: Theory, Research, and Treatment, 2014
Previous research indicates that borderline personality disorder (BPD) is well conceptualized as ... more Previous research indicates that borderline personality disorder (BPD) is well conceptualized as a dimensional construct that can be represented using normal personality traits. A previous study successfully developed and validated a BPD measure embedded within a normal trait measure, the Minnesota Borderline Personality Disorder Scale (MBPD). The current study performed a further validation of the MBPD by examining its convergent validity, external correlates, and heritability in a sample of 429 female twins. The MBPD correlated strongly with the Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II) screener for BPD and moderately with external correlates. Moreover, the MBPD and SCID-II screener exhibited very similar patterns of external correlations. Additionally, results indicated that the genetic and environmental influences on MBPD overlap with the genetic and environmental influences on the SCID-II screener, which suggests that these scales are measuring the same construct. These data provide further evidence for the construct validity of the MBPD.
A number of models for estimating the coecients of dynamical systems have been proposed. One is t... more A number of models for estimating the coecients of dynamical systems have been proposed. One is the exact discrete model, another is the latent dierences
Structural Equation Modeling: A Multidisciplinary Journal, 2002
Abstract Modern structural equation modeling software programs include user interfaces for the en... more Abstract Modern structural equation modeling software programs include user interfaces for the entry of graphical diagrams as a method for the production of the underlying matrices that are then manipulated in traditional ways to provide parameter estimates and fit statistics. This work presents an algorithm for the solution of the problem in the reverse order: automatically producing a graphical diagram from a matrix formula in such a way that its components are logically and hierarchically arranged. In the process, the individual path components of expected covariance between variables are calculated and feedback loops or so-called nonrecursive paths are recognized and tagged. Possible uses for this algorithm include automatic recognition of regions of structural underidentification in a model and the didactic graphical display of the components of expected covariance between variables. This algorithm relies on the matrix equations of , a general purpose SEM formulation.
OpenMx is free, full-featured, open source, structural equation modeling (SEM) software. OpenMx r... more OpenMx is free, full-featured, open source, structural equation modeling (SEM) software. OpenMx runs within the R statistical programming environment on Windows, Mac OS-X, and Linux computers. The rationale for developing OpenMx is discussed along with the philosophy behind the user interface. The OpenMx data structures are introduced-these novel structures define the user interface framework and provide new opportunities for model specification. Two short example scripts for the specification and fitting of a confirmatory factor model are next presented. We end with an abbreviated list of modeling applications available in OpenMx 1.0 and a discussion of directions for future development.
This paper investigates the precision of parameters estimated from local samples of time dependen... more This paper investigates the precision of parameters estimated from local samples of time dependent functions. We find that time delay embedding, i.e., structuring data prior to analysis by constructing a data matrix of overlapping samples, increases the precision of parameter estimates and in turn statistical power compared to standard independent rows of panel data. We show that the reason for this effect is that the sign of estimation bias depends on the position of a misplaced data point if there is no a priori knowledge about initial conditions of the time dependent function. Hence, we reason that the advantage of time delayed embedding is likely to hold true for a wide variety of functions. We support these conclusions both by mathematical analysis and two simulations. 159 design has the advantage of a large sample of individuals, and thus the standard error of the mean within-person time series coefficient may be small. In this example design, 1,000 observations were made: 5 observations on each of 200 individuals.
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Papers by Steven Boker