Experiments investigated whether infants infer that a hidden, freely moving object will move cont... more Experiments investigated whether infants infer that a hidden, freely moving object will move continuously and smoothly. Infants aged 6 and 10 months, like the 4-month-old infants in previous experiments, inferred that the object's path would be connected and unobstructed, in accord with the principle of continuity. In contrast, 4- and 6-month-old infants did not appear to infer that the object's path would be smooth, in accord with the principle of inertia. At 8 and 10 months, knowledge of inertia appeared to be emerging but remained weaker than knowledge of continuity. These findings are consistent with the view that common sense knowledge of physical objects develops by enrichment around constant core principles.
A goal of research in human-computer interaction is computer systems that can recognize and under... more A goal of research in human-computer interaction is computer systems that can recognize and understand nonverbal communication. In a series of studies, we developed semiautomated methods of discriminating emotion and para-linguistic communication in face and voice. In study 1, three computervision based modules reliably recognized FACS action units, which are the smallest visibly discriminable changes in facial expression. Automated Face Analysis demonstrated convergent validity with manual coding for 15 action units and action unit combinations central to the expression of emotion. In study 2, prosodic measures discriminated pragmatic intent in infantdirected speech with accuracy ranging from 61-65% in test samples. In study 3, facial EMG and prosodic measures combined discriminated between negative, neutral, and positive emotion with accuracy ranging from 47-79% in test samples. These results support the feasibility of human-computer interfaces that are sensitive to the full range...
In this study, the authors demonstrated that 6-month-old infants are able to categorize natural, ... more In this study, the authors demonstrated that 6-month-old infants are able to categorize natural, 650 Hz low-pass filtered infant-directed utterances. In Experiment 1,24 male and 24 female infants heard 7 different okens from 1 class of utterance (comforting or approving). Then, some infants heard a novel test stimulus from the familiar class of tokens; others heard a test stimulus from the unfamiliar class. Infants categorized these tokens as evidenced by response recovery to tokens from the unfamil-iar class but not to novel tokens from the familiar class ~ Experiment 2 confirmed that the infants were able to discriminate between closely matched tokens from within each category, supporting the conclusion that the results of Experiment 1 indicated categorization. The authors discuss both a mechanism that might explain the development of this ability and the mutual adaptation seen in parent-infant communication. When adults speak to infants, they typically produce utter-ances that ha...
Infant-directed speech is an important but difficult to measure aspect of caregiver-infant intera... more Infant-directed speech is an important but difficult to measure aspect of caregiver-infant interaction. Specialized training in speech science is required and processing is computationally intensive and time consuming. We developed a computer-assisted method of measuring infantdirected speech that requires little specialized training, has high concurrent validity with alternative approaches, and has improved efficiency in estimating frequency and temporal parameters. In Schematic Pitch Coding, an operator uses a computer interface to play digitized speech samples, view the corresponding narrow-band spectrograms, and mark points of inflection in fundamental frequency (f o ) using a computer mouse. Custom software generates graphic representations of f o contours and quantitative estimates of the mean and standard deviation of f o , utterance duration, and turn-taking pauses. Our current system, which is not optimized for speed, can process a 30-second sample of infant-directed speech...
Infant-directed speech is an important but difficult to measure aspect of caregiver-infant intera... more Infant-directed speech is an important but difficult to measure aspect of caregiver-infant interaction. Specialized training in speech science is required and processing is computationally intensive and time consuming. We developed a computer-assisted method of measuring infantdirected speech that requires little specialized training, has high concurrent validity with alternative approaches, and has improved efficiency in estimating frequency and temporal parameters. In Schematic Pitch Coding, an operator uses a computer interface to play digitized speech samples, view the corresponding narrow-band spectrograms, and mark points of inflection in fundamental frequency (fo) using a computer mouse. Custom software generates graphic representations of fo contours and quantitative estimates of the mean and standard deviation of fo, utterance duration, and turn-taking pauses. Our current system, which is not optimized for speed, can process a 30-second sample of infant-directed speech in a...
The impetus for the current study was from a student inquiry into the Levene Test that is used in... more The impetus for the current study was from a student inquiry into the Levene Test that is used in the very popular statistical package SPSS (Statistical Package for the Social Sciences) to test for homogeneity of variance prior to conducting tests of the equality of means. The student had read in David Howell's book Statistical Methods for Psychology, 5th Edition (Howell, 2002) that the Levene test may not be the best one available. The student wanted to know what research, if any, led to SPSS's decision to use this particular test for homogeneity of variance that is used in the independent samples t-test and one-way ANOVA. A subsequent literature search produced some research on the Levene Test (Brown & Forsyth, 1974; Levene, 1960; Tomarken & Serlin, 1986). A further search found other tests of homogeneity of variance in studies by Overall and Woodward (1974, 1976); O'Brien, (1981), and Levy (1975) that may have been better choices than the Levene Test. Brown and Forsyth (1974) compared the original Levene Test to two modifications of it. The original Levene Test used sample means. The modified Levene tests introduced by Brown and Forsyth (1974) used the median and the trimmed mean. They demonstrated through Monte Carlo studies that the median and the trimmed means outperformed the original test when the homogeneity of variance assumption was violated. Of particular interest is the modified Z-variance test presented by Overall and Woodward (1976). Overall and Woodward had compared the robustness and power of this modification against four other homogeneity-of-variance tests: (1) Z-variance unmodified, (2) Wilson-Hilferty (3) Bartlett and (4) Box. Using a series of Monte Carlo studies, Overall and Woodward (1976) demonstrated the superiority of the modified Z-variance test over the other four tests. Unfortunately, the Overall-Woodward modification of the Z-variance test is not well known. This modification appears only in a technical report that may no longer be available or easily accessible. A Google search for this modification did not produce any results. The O'Brien Test is also mentioned by Howell (2003) but little research could be found on it. From O'Brien's article (O'Brien, 1981) this test appears promising. With all of these more complicated formulas developed to measure homogeneity of variance, there is a simple one that will also be used in this study. The Fmax test developed by Hartley (1950) is very simple, involving no more than computing the ratio of the greatest subgroup variance and the smallest subgroup variance. In this study, all five homogeneity of variance tests were compared using a Monte Carlo approach. Of particular interest are the Overall-Woodward modification of the Z-variance test and the O'Brien Test. A major goal of the present study is to evaluate just how good the original Levene test is when compared to these other alternatives. "Goodness" of each test is determined by examining the robustness and power for each test. Should SPSS and other statistical packages consider using other tests along with the Levene? The Levene Test In 1960, Levene proposed an alternative method to the Bartlett Test (Bartlett, 1937) for testing the assumption of homogeneity of variance for the independent sample t-test and ANOVA designs. The Bartlett test works well for data that are normally or approximate normally distributed. The Bartlett test does not fare well for data that follow a leptokurtic or skewed distribution (Overall & Woodward, 1974). According to Levene (1960), the test he proposed was less sensitive to departures from normality. This says that the Levene Test had fewer Type 1 errors than the Bartlett Test for distributions that were aberrant from normality. The Levene Test is defined as the following: [H.sub.0]: [[sigma].sup.2.sub.1] = [[sigma].sup.2.sub.2] = [[sigma].sup.2.sub.3] = ... = [[sigma].sup.2.sub. …
In this study, the authors demonstrated that 6-month-old infants are able to categorize natural, ... more In this study, the authors demonstrated that 6-month-old infants are able to categorize natural, 650 Hz low-pass filtered infant-directed utterances. In Experiment 1, 24 male and 24 female infants heard 7 different tokens from 1 class of utterance (comforting or approving). Then, some infants heard a novel test stimulus from the familiar class of tokens; others heard a test stimulus from the unfamiliar class. Infants categorized these tokens as evidenced by response recovery to tokens from the unfamiliar class but not to novel tokens from the familiar class~ Experiment 2 confirmed that the infants were able to discriminate between closely matched tokens from within each category, supporting the conclusion that the results of Experiment 1 indicated categorization. The authors discuss both a mechanism that might explain the development of this ability and the mutual adaptation seen in parent-infant communication.
Infant-directed speech is an important but difficult-to-measure aspect of caregiver-infant intera... more Infant-directed speech is an important but difficult-to-measure aspect of caregiver-infant interaction. Specialized training in speech science is required and processing is computationally intensive and time consuming. We developed a computer-assisted method of measuring infant-directed speech that requires little specialized training, has high concurrent validity with alternative approaches, and has improved efficiency in estimating frequency and temporal parameters. In Schematic Pitch Coding, an operator uses a computer interface to play digitized speech samples, view the corresponding narrow-band spectrograms, and mark points of inflection in fundamental frequency (f 0) using a computer mouse. Custom software generates graphic representations of f 0 contours and quantitative estimates of the mean and standard deviation of f 0, utterance duration, and turn-taking pauses. Our current system, which is not optimized for speed, can process a 30-second sample of infant-directed speech ...
Experiments investigated whether infants infer that a hidden, freely moving object will move cont... more Experiments investigated whether infants infer that a hidden, freely moving object will move continuously and smoothly. Infants aged 6 and 10 months, like the 4-month-old infants in previous experiments, inferred that the object's path would be connected and unobstructed, in accord with the principle of continuity. In contrast, 4- and 6-month-old infants did not appear to infer that the object's path would be smooth, in accord with the principle of inertia. At 8 and 10 months, knowledge of inertia appeared to be emerging but remained weaker than knowledge of continuity. These findings are consistent with the view that common sense knowledge of physical objects develops by enrichment around constant core principles.
A goal of research in human-computer interaction is computer systems that can recognize and under... more A goal of research in human-computer interaction is computer systems that can recognize and understand nonverbal communication. In a series of studies, we developed semiautomated methods of discriminating emotion and para-linguistic communication in face and voice. In study 1, three computervision based modules reliably recognized FACS action units, which are the smallest visibly discriminable changes in facial expression. Automated Face Analysis demonstrated convergent validity with manual coding for 15 action units and action unit combinations central to the expression of emotion. In study 2, prosodic measures discriminated pragmatic intent in infantdirected speech with accuracy ranging from 61-65% in test samples. In study 3, facial EMG and prosodic measures combined discriminated between negative, neutral, and positive emotion with accuracy ranging from 47-79% in test samples. These results support the feasibility of human-computer interfaces that are sensitive to the full range...
In this study, the authors demonstrated that 6-month-old infants are able to categorize natural, ... more In this study, the authors demonstrated that 6-month-old infants are able to categorize natural, 650 Hz low-pass filtered infant-directed utterances. In Experiment 1,24 male and 24 female infants heard 7 different okens from 1 class of utterance (comforting or approving). Then, some infants heard a novel test stimulus from the familiar class of tokens; others heard a test stimulus from the unfamiliar class. Infants categorized these tokens as evidenced by response recovery to tokens from the unfamil-iar class but not to novel tokens from the familiar class ~ Experiment 2 confirmed that the infants were able to discriminate between closely matched tokens from within each category, supporting the conclusion that the results of Experiment 1 indicated categorization. The authors discuss both a mechanism that might explain the development of this ability and the mutual adaptation seen in parent-infant communication. When adults speak to infants, they typically produce utter-ances that ha...
Infant-directed speech is an important but difficult to measure aspect of caregiver-infant intera... more Infant-directed speech is an important but difficult to measure aspect of caregiver-infant interaction. Specialized training in speech science is required and processing is computationally intensive and time consuming. We developed a computer-assisted method of measuring infantdirected speech that requires little specialized training, has high concurrent validity with alternative approaches, and has improved efficiency in estimating frequency and temporal parameters. In Schematic Pitch Coding, an operator uses a computer interface to play digitized speech samples, view the corresponding narrow-band spectrograms, and mark points of inflection in fundamental frequency (f o ) using a computer mouse. Custom software generates graphic representations of f o contours and quantitative estimates of the mean and standard deviation of f o , utterance duration, and turn-taking pauses. Our current system, which is not optimized for speed, can process a 30-second sample of infant-directed speech...
Infant-directed speech is an important but difficult to measure aspect of caregiver-infant intera... more Infant-directed speech is an important but difficult to measure aspect of caregiver-infant interaction. Specialized training in speech science is required and processing is computationally intensive and time consuming. We developed a computer-assisted method of measuring infantdirected speech that requires little specialized training, has high concurrent validity with alternative approaches, and has improved efficiency in estimating frequency and temporal parameters. In Schematic Pitch Coding, an operator uses a computer interface to play digitized speech samples, view the corresponding narrow-band spectrograms, and mark points of inflection in fundamental frequency (fo) using a computer mouse. Custom software generates graphic representations of fo contours and quantitative estimates of the mean and standard deviation of fo, utterance duration, and turn-taking pauses. Our current system, which is not optimized for speed, can process a 30-second sample of infant-directed speech in a...
The impetus for the current study was from a student inquiry into the Levene Test that is used in... more The impetus for the current study was from a student inquiry into the Levene Test that is used in the very popular statistical package SPSS (Statistical Package for the Social Sciences) to test for homogeneity of variance prior to conducting tests of the equality of means. The student had read in David Howell's book Statistical Methods for Psychology, 5th Edition (Howell, 2002) that the Levene test may not be the best one available. The student wanted to know what research, if any, led to SPSS's decision to use this particular test for homogeneity of variance that is used in the independent samples t-test and one-way ANOVA. A subsequent literature search produced some research on the Levene Test (Brown & Forsyth, 1974; Levene, 1960; Tomarken & Serlin, 1986). A further search found other tests of homogeneity of variance in studies by Overall and Woodward (1974, 1976); O'Brien, (1981), and Levy (1975) that may have been better choices than the Levene Test. Brown and Forsyth (1974) compared the original Levene Test to two modifications of it. The original Levene Test used sample means. The modified Levene tests introduced by Brown and Forsyth (1974) used the median and the trimmed mean. They demonstrated through Monte Carlo studies that the median and the trimmed means outperformed the original test when the homogeneity of variance assumption was violated. Of particular interest is the modified Z-variance test presented by Overall and Woodward (1976). Overall and Woodward had compared the robustness and power of this modification against four other homogeneity-of-variance tests: (1) Z-variance unmodified, (2) Wilson-Hilferty (3) Bartlett and (4) Box. Using a series of Monte Carlo studies, Overall and Woodward (1976) demonstrated the superiority of the modified Z-variance test over the other four tests. Unfortunately, the Overall-Woodward modification of the Z-variance test is not well known. This modification appears only in a technical report that may no longer be available or easily accessible. A Google search for this modification did not produce any results. The O'Brien Test is also mentioned by Howell (2003) but little research could be found on it. From O'Brien's article (O'Brien, 1981) this test appears promising. With all of these more complicated formulas developed to measure homogeneity of variance, there is a simple one that will also be used in this study. The Fmax test developed by Hartley (1950) is very simple, involving no more than computing the ratio of the greatest subgroup variance and the smallest subgroup variance. In this study, all five homogeneity of variance tests were compared using a Monte Carlo approach. Of particular interest are the Overall-Woodward modification of the Z-variance test and the O'Brien Test. A major goal of the present study is to evaluate just how good the original Levene test is when compared to these other alternatives. "Goodness" of each test is determined by examining the robustness and power for each test. Should SPSS and other statistical packages consider using other tests along with the Levene? The Levene Test In 1960, Levene proposed an alternative method to the Bartlett Test (Bartlett, 1937) for testing the assumption of homogeneity of variance for the independent sample t-test and ANOVA designs. The Bartlett test works well for data that are normally or approximate normally distributed. The Bartlett test does not fare well for data that follow a leptokurtic or skewed distribution (Overall & Woodward, 1974). According to Levene (1960), the test he proposed was less sensitive to departures from normality. This says that the Levene Test had fewer Type 1 errors than the Bartlett Test for distributions that were aberrant from normality. The Levene Test is defined as the following: [H.sub.0]: [[sigma].sup.2.sub.1] = [[sigma].sup.2.sub.2] = [[sigma].sup.2.sub.3] = ... = [[sigma].sup.2.sub. …
In this study, the authors demonstrated that 6-month-old infants are able to categorize natural, ... more In this study, the authors demonstrated that 6-month-old infants are able to categorize natural, 650 Hz low-pass filtered infant-directed utterances. In Experiment 1, 24 male and 24 female infants heard 7 different tokens from 1 class of utterance (comforting or approving). Then, some infants heard a novel test stimulus from the familiar class of tokens; others heard a test stimulus from the unfamiliar class. Infants categorized these tokens as evidenced by response recovery to tokens from the unfamiliar class but not to novel tokens from the familiar class~ Experiment 2 confirmed that the infants were able to discriminate between closely matched tokens from within each category, supporting the conclusion that the results of Experiment 1 indicated categorization. The authors discuss both a mechanism that might explain the development of this ability and the mutual adaptation seen in parent-infant communication.
Infant-directed speech is an important but difficult-to-measure aspect of caregiver-infant intera... more Infant-directed speech is an important but difficult-to-measure aspect of caregiver-infant interaction. Specialized training in speech science is required and processing is computationally intensive and time consuming. We developed a computer-assisted method of measuring infant-directed speech that requires little specialized training, has high concurrent validity with alternative approaches, and has improved efficiency in estimating frequency and temporal parameters. In Schematic Pitch Coding, an operator uses a computer interface to play digitized speech samples, view the corresponding narrow-band spectrograms, and mark points of inflection in fundamental frequency (f 0) using a computer mouse. Custom software generates graphic representations of f 0 contours and quantitative estimates of the mean and standard deviation of f 0, utterance duration, and turn-taking pauses. Our current system, which is not optimized for speed, can process a 30-second sample of infant-directed speech ...
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