The detection of a tone added to a narrow band of noise: The energy model revisited

In an effort to determine whether cues related to changes in energy contribute to the detection of a tone added to a narrow band of noise, we examined the effect of level variation on detection thresholds. In the first experiment, the level of each waveform was randomly varied on each presentation. Level variation had only marginal effects on performance. In addition, detection thresholds were obtained using bands of noise with equal energy across intervals. Neither increasing nor decreasing the variance of the noise-alone and tone-plus-noise energy difference distributions altered the detectability of a tone added to noise. Thus, the changes in energy that are concomitant with the addition of the tone are not the sole cue for the detection of the tone. In a second experiment, three psychometric functions were measured. One function was determined using no level variation, one was measured in the presence of level variation, and one was measured in the context of level variation, but for trials without level variation. The context of level variation slightly reduced detectability. In a third experiment, we compared detectability in three conditions: no level variation, across-trial level variation, and across-interval level variation. The thresholds obtained in the absence of level variation were superior to those measured in the presence of level variation, regardless of the manner in which the level variation was incorporated.     

The Effect of Differential Post-Weaning Environment on the Rigidity of an Animal's Behavior

Seventy-two first, second and third grade boys and girls were administered seriation problems involving different combinations of shape and color variation. Success rates and latency scores were influenced by shape variation, but not by color variation or grade level. The failure to obtain predicted interactions between the effects of grade level and stimulus variation was attributed to the clarity of the relevant stimulus dimension.     

The influence of temporal and spatial variation on tactile identification of letters

This study was designed to show that variation in stimulation has an influence on tactile perception similar to that in the visual modality. Thirty-two subjects were required to identify Hebrew letters by the tactile sense. Identification time was found to be significantly (p less than .01) shorter when subjects could feel the letters both with temporal variation (i.e., vibrations) and spatial variation (i.e., allowing the subjects to move their fingers over the letters) than when the letters were stable. The longest identification time was found when both temporal and spatial variation were absent. The effects of the two types of tactile variation were found to be compensatory, and a possible explanation for that is offered. Possible implications of these results regarding the use of tactile perception in man-machine systems are discussed.     

形成性测量模型：结构方程模型的新视角

形成性测量模型(Formative Model, FM)是指标变异导致潜变量变异的模型, 反映性测量模型(Reflective Model, RM)是潜变量变异导致指标变异的模型。FM在模型界定、识别和估计、信效度评价以及模型应用等方面均与RM存在极大的不同。模型界定错误会使参数估计发生偏差, 影响统计结论的有效性, 应当审慎考虑指标和潜变量之间的关系, 选择恰当的测量模型。进一步揭示两者的区别和误用带来的偏差, 完善FM的识别和估计、信效度评价方法、对变量含义的解释以及高阶FM的理论解释和模型估计是未来的研究方向。     

The role of variation in the perception of accented speech

Phonetic variation has been considered a barrier that listeners must overcome in speech perception, but has been proved beneficial in category learning. In this paper, I show that listeners use within-speaker variation to accommodate gross categorical variation. Within the perceptual learning paradigm, listeners are exposed to p-initial words in English produced by a native speaker of French. Critically, listeners are trained on these words with either invariant or highly-variable VOTs. While a gross boundary shift is made for participants exposed to the variable VOTs, no such shift is observed after exposure to the invariant stimuli. These data suggest that increasing variation improves the mapping of perceptually mismatched stimuli.     

Representational specificity of within-category phonetic variation in the long-term mental lexicon

This study examines the potential encoding in long-term memory of subphonemic, within-category variation in voice onset time (VOT) and the degree to which this encoding of subtle variation is mediated by lexical competition. In 4 long-term repetition-priming experiments, magnitude of priming was examined as a function of variation in VOT in words with voiced counterparts (cape-gape) and without (cow-*gow) and words whose counterparts were high frequency (pest-best) or low frequency (pile-bile). The results showed that within-category variation was indeed encoded in memory and could have demonstrable effects on priming. However, there were also robust effects of prototypical representations on priming. Encoding of within-category variation was also affected by the presence of lexical counterparts and by the frequency of counterparts.     

Evidence for instrument and family-specific variation of subclinical psychosis dimensions in the general population

It is unknown to what degree dimensions of schizotypy (subclinical psychosis) show independent, family-specific variation in the general population. Psychologists administered the Community Assessment of Psychic Experiences, the Structured Interview for Schizotypy-Revised (SIS-R), and the Brief Psychiatric Rating Scale to 257 subjects pertaining to 82 general population families. All 3 instruments showed family-specific variation for positive and negative subclinical psychosis dimensions with between-families proportions of total variance between 10% and 40%. However, only the SIS-R showed family-specific variation of the negative dimension independent of its correlation with the positive dimension. The positive dimension of subclinical psychosis shows familial-specific variation in samples unselected for psychiatric disorder, suggesting dimensional liability in the population. The SIS-R additionally captures family-specific variation in the negative domain.     

Suicide and homicide rates: their relationship to latitude and longitude and to the weather

The variation of suicide and homicide rates in the major standard metropolitan statistical areas of the United States was explored to see whether regional variations in temperature and precipitation could account for some of the variation. Controls for temperature eliminated the North-South variation in suicide rates, but not the North-South variation in homicide rates or the East-West variation in suicide rates. Only the correlation between precipitation and homicide rates survived controls for latitude and longitude.     

On the perception of speech from time-varying acoustic information: contributions of amplitude variation

The cyclic variation in the energy envelope of the speech signal results from the production of speech in syllables. This acoustic property is often identified as a source of information in the perception of syllable attributes, though spectral variation can also provide this information reliably. In the present study of the relative contributions of the energy and spectral envelopes in speech perception, we employed sinusoidal replicas of utterances, which permitted us to examine the roles of these acoustic properties in establishing or maintaining time-varying perceptual coherence. Three experiments were carried out to assess the independent perceptual effects of variation in sinusoidal amplitude and frequency, using sentence-length signals. In Experiment 1, we found that the fine grain of amplitude variation was not necessary for the perception of segmental and suprasegmental linguistic attributes; in Experiment 2, we found that amplitude was nonetheless effective in influencing syllable perception, and that in some circumstances it was crucial to segmental perception; in Experiment 3, we observed that coarse-grain amplitude variation, above all, proved to be extremely important in phonetic perception. We conclude that in perceiving sinusoidal replicas, the perceiver derives much from following the coherent pattern of frequency variation and gross signal energy, but probably derives rather little from tracking the precise details of the energy envelope. These findings encourage the view that the perceiver uses time-varying acoustic properties selectively in understanding speech.     

The role of variation in thought experiments

The main concern of this paper is to show that understanding mental variation may prove to be relevant to inquiry into thought experiments. First, I examine why Ernst Mach considered the ability to vary the contents of one's thoughts the principal requirement for thought experimentation. Second, I illustrate the wide applicability of mental variation in thought experiments. Third, I suggest, following Kathleen Wilkes, that variation is frequently employed in “realistic” thought experiments.     

The nature of extraversion: a genetical analysis.

A biometrical-genetical analysis of twin data to elucidate the determinants of variation in extraversion and its components, sociability and impulsiveness, revealed that both genetical and environmental factors contributed to variation in extraversion, to the variation and covariation of its component scales, and to the interaction between subjects and scales. A large environmental correlation between the scales suggested that environmental factors may predominate in determining the unitary nature of extraversion. The interaction between subjects and scales depended more on genetical factors, which suggests that the dual nature of extraversion has a strong genetical basis. A model assuming random mating, additive gene action, and specific environmental effects adequately describes the observed variation and covariation of sociability and impulsiveness. Possible evolutionary implications are discussed.     

The eclipse of heritability and the foundations of intelligence

It is well known that theory in human cognitive ability or ‘intelligence’ is not well developed, especially with regard to sources of trait variation. Roots of theory have been sought in biology, and it is now widely accepted, on the basis of twin studies, and statistical analysis of variance, that at least half of the normal trait variation can be attributed to genetic variation, a correlation known as the trait ‘heritability’. Since the 1990s, methods in molecular biology have been adopted to go ‘beyond’ this mere statistical attribution to the identification of individual genes responsible for trait variation. More than a decade of intense effort, however, has failed to produce unambiguous, replicable findings; explanations for the ‘missing heritability’ are now being demanded; and calls for new perspectives on the roles of genes and environments in development and trait variation are being demanded. Here, I propose a dynamic systems perspective indicating how the processes in which heritability becomes missing are the very ones that provide the roots of new intelligence theory.     

The encoding of rate and talker information during phonetic perception

The acoustic structure of the speech signal is extremely variable due to a variety of contextual factors, including talker characteristics and speaking rate. To account for the listener’s ability to adjust to this variability, speech researchers have posited the existence of talker and rate normalization processes. The current study examined how the perceptual system encoded information about talker and speaking rate during phonetic perception. Experiments 1–3 examined this question, using a speeded classification paradigm developed by Garner (1974). The results of these experiments indicated that decisions about phonemic identity were affected by both talker and rate information: irrelevant variation in either dimension interfered with phonemic classification. While rate classification was also affected by phoneme variation, talker classification was not. Experiment 4 examined the impact of talker and rate variation on the voicing boundary under different blocking conditions. The results indicated that talker characteristics influenced the voicing boundary when talker variation occurred within a block of trials only under certain conditions. Rate variation, however, influenced the voicing boundary regardless of whether or not there was rate variation within a block of trials. The findings from these experiments indicate that phoneme and rate information are encoded in an integral manner during speech perception, while talker characteristics are encoded separately.     

The origins of extraversion: joint effects of facultative calibration and genetic polymorphism

The origins of variation in extraversion are largely mysterious. Recent theories and some findings suggest that personality variation can be orchestrated by specific genetic polymorphisms. Few studies, however, have examined an alternative hypothesis that personality traits are facultatively calibrated to variations in other phenotypic features, and none have considered how these distinct processes may interact in personality determination. Since physical strength and physical attractiveness likely predicted the reproductive payoffs of extraverted behavioral strategies over most of human history, it was theorized that extraversion is calibrated to variation in these characteristics. Confirming these predicted patterns, strength and attractiveness together explained a surprisingly large fraction of variance in extraversion across two studies--effects that were independent of variance explained by an androgen receptor gene polymorphism. These novel findings initially support an integrative model wherein facultative calibration and specific genetic polymorphisms operate in concert to determine personality variation.     

Looking for a structural network: effects of changing size and style on letter recognition.

The accuracy of identifying backward-masked strings of unrelated letters was measured to test a prediction of a structural network model in which information about the absolute size of letters in a font is factored out from other types of information and is represented by a single size parameter. In this model, variation from block to block in the font size should be handled relatively easily by changing this parameter. In contrast, variation in several aspects of the font style would require changing multiple parameters and should be more difficult. In three experiments, the font was alternated in style, size, size and style, or not at all, at the end of each block of eight trials. The accuracy was lower overall when the font was varied, but contrary to the predictions of the model, variation in size reduced the accuracy of performance as much as did variation in style and variation in size and style.     

Growing Up with Child Sexual Abuse in an Experimental Commune: Making Sense of Narrative Variation

The legitimacy of adult's accounts of child sexual abuse depends on the consistency of the story they tell about this experience. But there are a variety of influences that conspire to create dynamic variation in retrospective accounts of child sexual abuse. In a study of an experimental New Zealand commune called Centrepoint, participants showed considerable variation in accounting for the child sexual abuse that was known to have occurred there. We used a narrative methodology to show the variation between stories that highlighted abuse and suffering and others that represented an idyllic childhood within which sex between children and adults was normalised. There was also considerable variation within individual participant's accounts. The variation within and between accounts was shaped by features such exposure to contradictory experiences, different social positioning in relation to child sexual abuse, shifts in memory and interpretation over time, differences between insider and outsider perspectives on child sexual activity at the commune and alternative perspectives on victimhood. This research challenges the mythology that accounts of child sexual abuse should be expected to be clear and consistent. Instead, variation should be treated the rule rather than the exception in these accounts. Copyright © 2012 John Wiley & Sons, Ltd.     

Accommodating variation: dialects, idiolects, and speech processing

Listeners are faced with enormous variation in pronunciation, yet they rarely have difficulty understanding speech. Although much research has been devoted to figuring out how listeners deal with variability, virtually none (outside of sociolinguistics) has focused on the source of the variation itself. The current experiments explore whether different kinds of variation lead to different cognitive and behavioral adjustments. Specifically, we compare adjustments to the same acoustic consequence when it is due to context-independent variation (resulting from articulatory properties unique to a speaker) versus context-conditioned variation (resulting from common articulatory properties of speakers who share a dialect). The contrasting results for these two cases show that the source of a particular acoustic-phonetic variation affects how that variation is handled by the perceptual system. We also show that changes in perceptual representations do not necessarily lead to changes in production.     

The Modulation of Operant Variation by the Probability, Magnitude, and Delay of Reinforcement

Recent studies have demonstrated that the expectation of reward delivery has an inverse relationship with operant behavioral variation (e.g., Stahlman, Roberts, & Blaisdell, 2010). Research thus far has largely focused on one aspect of reinforcement – the likelihood of food delivery. In two experiments with pigeons, we examined the effect of two other aspects of reinforcement: the magnitude of the reward and the temporal delay between the operant response and outcome delivery. In the first experiment, we found that a large reward magnitude resulted in reduced spatiotemporal variation in pigeons’ pecking behavior. In the second experiment, we found that a 4-s delay between response-dependent trial termination and reward delivery increased variation in behavior. These results indicate that multiple dimensions of the reinforcer modulate operant response variation.     

Whiteness constancy: Inference or insensitivity?

Two general viewpoints were advanced as explanations of whiteness constancy: (a) an inferential process, in which noise illuminance variation) is suppressed, and (b) an insensitivity hypothesis, in which Os show an insensitivity to illuminance variation in well-articulated fields. Category judgments of illuminance and albedo variation were given by three Os to either unpatterned (isolated surface) or patterned (two surfaces, one of which was constant in albedo) stimuli. Judgments of the patterned stimuli differed from judgments of the unpatterned stimuli in that Os showed increased sensitivity to real albedo variation (whiteness constancy) and a corresponding decreased sensitivity to real illuminance variation, allowing the interpretation that stimulus conditions producing whiteness constancy are also those producing insensitivity to illuminance variation.