Search

We examine the English origins of Sranan, the English-lexicon creole of Suriname, as well as the necessity for presuming a mediating variety of colonial English as the source of the English features in Sranan. A comparison between the linguistic features of 45 Sranan words of English origin and those of the speech samples included in the Survey of English Dialects, when combined with an analysis of historical records of migration from England to the New World, suggests that Sranan was influenced by two clusters of lects, one from the South and West of England, and the other from East Anglia and the Southeast. In addition, we weigh the evidence concerning variation in word-initial phonemic /h/ and post-vocalic rhoticity, and conclude that it is not necessary to presume a mediating or leveled variety of colonial English (e.g., a koine) as the source for the feature values in the Sranan-45.

To determine if ivacaftor (Kalydeco) influences non-CF human CFTR function in vivo, we measured CFTR-dependent (C-sweat) and CFTR-independent (M-sweat) rates from multiple identified sweat glands in 8 non-CF adults. The two types of sweating were stimulated sequentially with intradermal injections of appropriate reagents; each gland served as its own control via alternating off-on drug tests on both arms, given at weekly intervals with 3 off and 3 on tests per subject. We compared drug effects on C-sweating stimulated by either high or low concentrations of β-adrenergic cocktail, and on methacholine-stimulated M-sweating. For each subject we measured ~700 sweat volumes from ~75 glands per arm (maximum 12 readings per gland), and sweat volumes were log-transformed for statistical analysis. T-tests derived from linear mixed models (LMMs) were more conservative than the familiar paired sample t-tests, and show that ivacaftor significantly increased C-sweating stimulated by both levels of agonist, with a larger effect in the low cocktail condition; ivacaftor did not increase M-sweat. Concurrent sweat chloride tests detected no effect of ivacaftor. We conclude that ivacaftor in vivo increases the open channel probability (PO) of WT CFTR, provided it is not already maximally stimulated.

Previous research has shown that American culture places a premium on excitement, enthusiasm, and other high-arousal positive states (HAP) compared with various East Asian cultures. In two studies, we tested the prediction that valuing HAP would be associated with less positive personal views of old age (i.e., fewer things people looked forward to and more things they dreaded about old age) in samples of European American, Chinese American, and Hong Kong Chinese younger, middle-aged, and older adults. In Study 1 (N = 849), participants rated how much they ideally wanted to feel HAP during a typical week and described their personal views of old age. As predicted, European American middle and older adults valued HAP more than did their Chinese American and Hong Kong Chinese peers, and these differences in ideal HAP were related to less positive personal views of old age. In Study 2 (N = 164), we experimentally manipulated how much individuals valued HAP and then assessed their personal views of old age: Across cultures, participants in the "value HAP" condition had less positive personal views of old age than did those in the control condition. These effects did not emerge for societal views of old age (i.e., what people associated with "someone" old vs. young). Together, these findings suggest that people's personal views of their own old age are due, in part, to how much excitement they ideally want to feel. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

African-American Vernacular English (AAVE) is systematic, rooted in history, and important as an identity marker and expressive resource for its speakers. In these respects, it resembles other vernacular or nonstandard varieties, like Cockney or Appalachian English. But like them, AAVE can trigger discrimination in the workplace, housing market, and schools. Understanding what shapes the relative use of AAVE vs. Standard American English (SAE) is important for policy and scientific reasons. This work presents, to our knowledge, the first experimental estimates of the effects of moving into lower-poverty neighborhoods on AAVE use. We use data on non-Hispanic African-American youth (n = 629) from a large-scale, randomized residential mobility experiment called Moving to Opportunity (MTO), which enrolled a sample of mostly minority families originally living in distressed public housing. Audio recordings of the youth were transcribed and coded for the use of five grammatical and five phonological AAVE features to construct a measure of the proportion of possible instances, or tokens, in which speakers use AAVE rather than SAE speech features. Random assignment to receive a housing voucher to move into a lower-poverty area (the intention-to-treat effect) led youth to live in neighborhoods (census tracts) with an 11 percentage point lower poverty rate on average over the next 10-15 y and reduced the share of AAVE tokens by ∼3 percentage points compared with the MTO control group youth. The MTO effect on AAVE use equals approximately half of the difference in AAVE frequency observed between youth whose parents have a high school diploma and those whose parents do not.

Phylogenies constructed from language Strickland from localities in England and Sranan. (A) Tree constructed from 86 localities in England and Sranan, with three migration events allowed. (B) Tree constructed from 126 localities in England and Sranan, with three migration events allowed.

Background: Growing evidence indicates that major depressive disorder (MDD) is characterized by accelerated biological aging, including greater age-related changes in physiological functioning. The disorder is also associated with abnormal neural reward circuitry, particularly in the basal ganglia (BG). Here we assessed age-related changes in BG volume in both patients with MDD and healthy control participants. Methods: We obtained whole-brain T1-weighted images from patients with MDD and healthy controls. We estimated grey matter volumes of the BG, including the nucleus accumbens, caudate, pallidum and putamen. Volumes were assessed using multivariate analysis of covariance (MANCOVA) with age as a covariate, followed by appropriate post hoc tests. Results: We included 232 individuals (116 patients with MDD) in our analysis. The MANCOVA yielded a significant group × age interaction (p = 0.043). Analyses for each region yielded a significant group × age interaction in the putamen (univariate test, p = 0.005; permutation test, p = 0.004); this effect was not significant in the other regions. The negative association between age and putamen volume was twice as large in the MDD than in the control group (−35.2 v. −16.7 mm3/yr), indicating greater age-related volumetric decreases in the putamen in individuals with MDD than in controls. Limitations: These findings are cross-sectional; future studies should assess the longitudinal impact of accelerated aging on anhedonia and neural indices of reward processing. Conclusion: Our results indicate that putamen aging is accelerated in patients with MDD. Thus, the putamen may uniquely contribute to the adverse long-term effects of depressive psychopathology and may be a useful target for the treatment of MDD across the lifespan.

Creole languages are formed in conditions where speakers from distinct languages are brought together without a shared first language, typically under the domination of speakers from one of the languages and particularly in the context of the transatlantic slave trade and European colonialism. One such Creole in Suriname, Sranan, developed around the mid-seventeenth century, primarily out of contact between varieties of English from England, spoken by the dominant group, and multiple West African languages. The vast majority of the basic words in Sranan come from the language of the dominant group, English. Here, we compare linguistic features of modern-day Sranan with those of English as spoken in 313 localities across England. By way of testing proposed hypotheses for the origin of English words in Sranan, we find that 80% of the studied features of Sranan can be explained by similarity to regional dialect features at two distinct input locations within England, a cluster of locations near the port of Bristol and another cluster near Essex in eastern England. Our new hypothesis is supported by the geographical distribution of specific regional dialect features, such as post-vocalic rhoticity and word-initial ‘h’, and by phylogenetic analysis of these features, which shows evidence favouring input from at least two English dialects in the formation of Sranan. In addition to explicating the dialect features most prominent in the linguistic evolution of Sranan, our historical analyses also provide supporting evidence for two distinct hypotheses about the likely geographical origins of the English speakers whose language was an input to Sranan. The emergence as a likely input to Sranan of the speech forms of a cluster near Bristol is consistent with historical records, indicating that most of the indentured servants going to the Americas between 1654 and 1666 were from Bristol and nearby counties, and that of the cluster near Essex is consistent with documents showing that many of the governors and important planters came from the southeast of England (including London) (Smith 1987 The Genesis of the Creole Languages of Surinam ; Smith 2009 In The handbook of pidgin and creole studies , pp. 98–129). This article is part of the theme issue ‘Bridging cultural gaps: interdisciplinary studies in human cultural evolution’.

To determine if oral dosing with the CFTR-potentiator ivacaftor (VX-770, Kalydeco) improves CFTR-dependent sweating in CF subjects carrying G551D or R117H-5T mutations, we optically measured sweat secretion from 32-143 individually identified glands in each of 8 CF subjects; 6 F508del/G551D, one G551D/R117H-5T, and one I507del/R117H-5T. Two subjects were tested only (-) ivacaftor, 3 only (+) ivacaftor and 3 (+/-) ivacaftor (1-5 tests per condition). The total number of gland measurements was 852 (-) ivacaftor and 906 (+) ivacaftor. A healthy control was tested 4 times (51 glands). For each gland we measured both CFTR-independent (M-sweat) and CFTR-dependent (C-sweat); C-sweat was stimulated with a β-adrenergic cocktail that elevated [cAMP]i while blocking muscarinic receptors. Absent ivacaftor, almost all CF glands produced M-sweat on all tests, but only 1/593 glands produced C-sweat (10 tests, 5 subjects). By contrast, 6/6 subjects (113/342 glands) produced C-sweat in the (+) ivacaftor condition, but with large inter-subject differences; 3-74% of glands responded with C/M sweat ratios 0.04%-2.57% of the average WT ratio of 0.265. Sweat volume losses cause proportionally larger underestimates of CFTR function at lower sweat rates. The losses were reduced by measuring C/M ratios in 12 glands from each subject that had the highest M-sweat rates. Remaining losses were estimated from single channel data and used to correct the C/M ratios, giving estimates of CFTR function (+) ivacaftor = 1.6%-7.7% of the WT average. These estimates are in accord with single channel data and transcript analysis, and suggest that significant clinical benefit can be produced by low levels of CFTR function.

When given a choice, how do people decide which physician to select? Although significant research has demonstrated that how people actually feel (their “actual affect”) influences their health care preferences, how people ideally want to feel (their “ideal affect”) may play an even greater role. Specifically, we predicted that people trust physicians whose affective characteristics match their ideal affect, which leads people to prefer those physicians more. Consistent with this prediction, the more participants wanted to feel high arousal positive states on average ([ideal HAP]; e.g., excited), the more likely they were to select a HAP-focused physician. Similarly, the more people wanted to feel low arousal positive states on average ([ideal LAP]; e.g., calm), the more likely they were to select a LAP-focused physician. Also as predicted, these links were mediated by perceived physician trustworthiness. Notably, while participants’ ideal affect predicted physician preference, actual affect (how much people actually felt HAP and LAP on average) did not. These findings suggest that people base even serious decisions on how they want to feel and highlight the importance of considering ideal affect in models of decision making, person perception, and patient physician communication.

The women portrayed in the bijin-ga of the past, particularly those from the Meiji Period (1868–1912), tended not to show much resemblance to those of women portrayed in the more modern bijin-ga (from after World War II), and such an observation came across as a possible indication that Japanese standards of beauty have changed over the two eras. To examine whether the apparent discrepancy can be interpreted as an actual change in the standards or not, a study was designed with the aim of assigning numeric values to several aspects of the eyes and testing for the presence of a statistically significant difference in each of the aspects between the Meiji bijin-ga and the modern bijin-ga. For this study, 29 Meiji bijin-ga and 36 modern bijin-ga were selected. The eye was chosen as the subject of comparison, and five aspects were categorized and measured: (1) presence or absence of a double fold, (2) eye width, (3) eye height, (4) eyebrow-to-upper lid distance, and (D) corneal diameter. The eye width, the eye height, and the eyebrow-to-upper lid distance were divided by the corneal diameter to derive standardized grounds for comparison. The difference in double-fold frequencies between the Meiji bijin-ga (24%) and the modern bijin-ga (36%) was not found to be statistically significant (p = 0.298). There was no difference in the eye width-to-corneal diameter ratio between the Meiji bijin-ga (mean 2.57 ± 0.6) and the modern bijin-ga (mean 2.61 ± 0.85) (p = 0.86). The eye height-to-corneal diameter ratio derived from the Meiji bijin-ga (mean 0.62 ± 0.15) was significantly smaller than that derived from the modern bijin-ga (mean 0.82 ± 0.18) (p = 0.000). The eyebrow to upper lid distance-to-corneal diameter ratio derived from the Meiji bijin-ga (mean 2.21 ± 0.83) was significantly greater than that derived from the modern bijin-ga (mean 1.36 ± 0.78) (p = 0.000). The results of the study support the notion that Westernization contributed to bringing about changes in the Japanese standards of beautiful eyes in the context of bijin-ga. However, the fact that the changeover has not occurred in all the categories in question does not indicate that the Occidental characteristics came to be emulated in their entirety. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors at http://www.springer.com/00266 .

The theory of signal detectability typically tits data from Yes-No detection experiments by assuming a particular form for the noise and signal plus noise distributions of the Observer. Previous work suggests that estimates of the Observer’s sensitivity are little affected by small discrepancies between the assumed distributions (usually Gaussian) and the Observer’s true underlying distributions. Possibly for this reason, estimates of the Observer’s choice of criterion or likelihood ratio suggesting suboptimal performance have also been taken at face value. It is, for example, commonly accepted that human Observers are conservafive: They are said to choose criteria corresponding to likelihood ratios that are closer to 1 than the ratios produced by optimal criteria. We demonstrate that estimates of likelihood ratio can be markedly biased when the distributions assumed in estimation are not the Observer’s true distributions. We derive necessary and sufficient conditions for an optimal Observer to appear conservative when fitted by distributions different from those governing his choices. These results raise a fundamental question: What information about the Observer’s underlying noise and signal plus noise distributions does the Observer’s performance in a Yes-No detection task provide? We demonstrate that a small number of isosensitivity (ROC) curves completely determines the Observer’s underlying noise and signal plus noise distributions for many familiar forms of the theory of signal detectability. These results open up the possibility of a semiparametric theory of signal detectability. el 1991 Academic Press, Inc.

Participants recruited from one Historically Black University (HBU) and two predominantly White higher-education institutions evaluated and decided simulated voting rights case summaries in which the plaintiff was either a racially-defined (African American) or a nonracially-defined (farmers) minority group. Contrary to social identity and social justice findings of an in-group bias, the present study showed greater support at all institutions for the voting rights of the African Americans than for the rural farmers, and the greatest support for both minority groups was found at the HBU. Perceived evidence strength was a better predictor of decisions than perceived unfairness, and both of these predictor variables completely mediated the effects of institution-type and involvement of a racially-defined group on decisions.

Link and Heath [1975] have analysed a random walk model for two-choice reaction time on the assumption that the two probability density functions (p.d.f.s) of the step-size, each p.d.f. corresponding to one stimulus, are mirror reflections of each other; and they have demonstrated the critical role played by the symmetry of the moment generating function (m.g.f.) of the step size in the determination of whether or not error and correct reaction times are equal. It is shown here that, given reflection symmetry, m.g.f. symmetry is necessary and sufficient for the random walk model to be equivalent to a sequential probability ratio test.

Iterated Prisoner's Dilemma models are proposed in which, at any trial, the probability of staying in the game depends on the outcome of the previous trial. If a player's choice depends on its own play (cooperate or defect) at the previous trial, it becomes possible for cooperative strategies to increase when rare in a population of egoists. A dynamic analysis is used to demonstrate that stable polymorphisms may result, and may involve more strategies than just Tit-for-Tat and all-Defect. The tendency for clustering among like strategists to enhance their initial increase when rare is also explored dynamically.

When subjects are asked to judge the duration and size of visually presented circles that vary in duration and size, perceived duration is directly related to stimulus size and perceived size is, in most cases, directly related to stimulus duration. When subjects are asked to process time and size information simultaneously, their time judgments are the same as when only time processing is required, but their size judgments are less than when only size processing is required. These data are discussed within the context of an explicit model for the processing of size information, added to which is the assumption that time judgments are influenced by the time spent processing size information.

Existing models of the foraging behavior of single-prey loaders in patchy environments differ on whether the optimal forager is predicted to stay in a patch until a prey is found, or to leave a patch for a next one if a prey is not found by a certain “deadline.” This article examines conditions on the probability distribution of prey density across patches that are necessary or sufficient for the existence of a finite, optimal deadline. It is shown that, for environments in which prey density is variable but never falls below some strictly positive level, a finite, optimal deadline exists when and only when the spatial density of patches is “high.” Also, a characterization is given of a large class of distributions (including the gamma distribution) for which a finite, optimal deadline exists for all levels of spatial density of patches.

This article analyzes the game-theoretic stability of three strategies, Tit-For-Tat (TFT), all-Defect (all-D), and all-Cooperate (all-C), that actors might use for repeated plays of the Prisoner's Dilemma (PD). The probability that there will be a next play is assumed to depend on the current behavior of one of the actors—it is w after cooperation and u after a defection—and two cases are examined. The first case is where an actor assumes that the continuation probability depends on its own behavior, and the second is where the continuation probability is assumed to depend on the other actor's behavior. It is shown that the potential for mutual cooperation is higher in the first case than in the second. A detailed examination of the first case reveals that when the ratio (1 - w)/(1 - u) is sufficiently extreme for certain classes of PD, the “cooperative” strategy TFT is stable and the “noncooperative” strategy all-D is unstable. For these classes of PD, it is thus possible both for cooperation to be maintained once it is established, and for cooperation to become established in a world of defectors. The sensitivity of these results to the precision in measurement of payoffs and probabilities is discussed.

The effect on identification and location of briefly presented targets (letters and blanks) of number of targets, retinal location, and direction and distance of simultaneously presented targets is investigated. In three different conditions, one, two, or three targets are presented on a trial with the location of targets varying from trial to trial. A model is proposed to describe identification and location performance in the one-letter condition. This model distinguishes between two sets of parameters, perceptual parameters and decision parameters, and assumes that in terms of these parameters, identification and location are independent processes. The perceptual and decision parameters of the model, estimated by assuming that these parameters are linearly related to retinal location, indicate that retinal location has a different effect on the decision parameters for both identification and location than on the perceptual parameters. Variables affecting the performance decrements found when multiple letters are presented are evaluated in terms of models stated for the multiple letter conditions. Estimates of the effects of distance from the fixation point and inter-letter distance indicate that, as both of these variables increase, performance decreases. In the three-letter condition, a serial position effect is found, with performance on center letters being relatively poor. A peripherally presented letter is found to have a large detrimental effect on performance, and the effect increases as interletter distance increases. Location of correctly identified targets follows many of the same patterns as identification performance in the multiple letter conditions. In addition, there is a tendency for incorrectly located targets to be moved foveally and to move to positions occupied by other targets on the trial. The possibility of a limited-capacity attention mechanism operating in the present experiment is discussed.

When a visual field is presented for 40 or 80 msec and a subject is asked to judge the duration of the stimulus, judged duration is found to be less when the field is blank than when the field contains three letters, but is the same whether the three letters form a word or not. The perceived difference between “filled” and “blank” fields increases when the subject is required to memorize the presented letters. These data are consistent with a theory which assumes,inter alia, that a stimulus is analyzed by a visual information processor and a timer, that attention is shared between these processors, and that temporal judgments are based on the output of both processors.

This paper examines the extent to which preparatory processes are selective (a) between two performance measures, speed and accuracy, (b) within a processing stage, for example, stimulus encoding and response execution, and (c) among possible stimulus presentation times. It is shown that the appearance of selectivity between speed and accuracy depends on whether these variables are considered over the possible preparatory states on a given trial, over the trials within an experimental condition, or over different conditions, and the relevance of this result to the measurement of processing capacity is discussed. Selectivity within processing stages is demonstrated by applying a parametric processing model to data from letter-matching tasks in which the identity of the first letter is probabilistically related to that of the second letter. In these tasks, reaction time differences between physical and name matches and between same and different responses depend on the stimulus and response contingencies and on the stimulus presentation times. Finally, a method is presented for resolving observed error rates into components that reflect the accuracy of each processing stage.

Probability matching is contraindicated by the data of individual subjects (Dusoir, 1974) and by group data (Creelman & Donaldson, 1968); in general, response frequencies are not as extreme (i.e., distant from one-half) as the corresponding stimulus frequencies. This deviation from probability matching can be accounted for by at least two versions of an error-correcting model in which the subject’s decision criterion may shift only after an error, but not by a model which permits criterion shifts after correct responses. One version of the error-correcting model allows us to specify the dependence of response frequency on payoff magnitude and on signal strength. The deviation from matching is consistent also with a model that assumes that, on each trial, the criterion shifts in the direction of the sensory information, regardless of response accuracy. This model is thus applicable to situations in which trial-by-trial feedback is omitted.

This article considers the problem of finding the optimal rule for assigning liability on the basis of fault when there is (a) error in the assessment of fault, (b) a probability distribution of true fault across the population of possible litigants, and (c) a value attached to the deterrence effect of a rule. The discussion is placed in the legal context of Contributory Negligence, and parallels are drawn between the present approach and the ‘economic’ approach to liability. A contributory negligence rule is said to be optimal if it minimizes a weighted sum of the cost of assessment error and the cost of the deviation between a rule and the ‘optimally deterrent’ rule. It is shown that the form of the optimal rule depends on the ‘importance’ of deterrence and on the probability distribution of plaintiffs with respect to fault. Sufficient conditions are given for each of the extant contributory negligence rules to approximate the optimal rule. It is argued that, in designing the law, the preference among rules should be based on the relative plausibility of these sufficient conditions, some of which may be verifiable empirically.

Hypotheses are stated about the relationships among the level of task difficulty chosen by a subject in a sequential task, expectancy of success, own outcome and that of a paired subject, and satisfaction with own outcome. Multiple regression analyses were used to test these hypotheses on data from an experiment in which subjects worked in pairs for six trials. It was found that the difficulty level chosen on a given trial was predicted by the difficulty level, the subject's outcome score, and the subject's satisfaction on the previous trial; that level of satisfaction on a trial was predicted by the subject's own outcome score and the difference in outcome scores between the two subjects on that trial; and that expectancy was predicted by difficulty level on the same trial. These results underscore the important mediating role of outcome evaluation in the control of behavior, and are consistent with previous research showing a dependence of evaluation on social comparison processes. Also consistent with previous research is the observed trend over trials to more difficult tasks. The “slope” of this trend depended on the initial difficulty level, a result which is readily accounted for by a simplified version of our hypotheses.

In a report paradigm, two letters are presented on a trial which are either confusable(e.g., P and R) or nonconfusable (e.g., P and M) in terms of visual features. Across trials, interletter distance, retinal location, duration, and visual field are varied. Identification accuracy on confusable trials was generally lower than on nonconfusable trials, and this effect of level of confusability increased with distance from the fixation point, decreased with duration, and was smaller on the central letter than on the more peripheral letter. A quantitative model, incorporating aspects of the interactive channels model (Estes, 1972) and feature perturbation model (Wolford, 1975), is developed and tested. One parameter of the model measures the effective similarity between two letters after lateral inhibition has occurred, and other parameters measure the probability of feature perturbation in foveal and peripheral directions.

This paper examines the equilibrium relation between the wage and profit rates for a technology in which technical parameters vary continuously. It is shown that the existence of a wage-profit frontier implies the existence of functional relationships among the technical parameters. These relationships, called herein characteristic functions, can be expressed in terms of one or more than one independent variable, and it is shown that given certain weak conditions on the functions, only in the former case is reswitching of techniques possible. An inequality is established involving the rates of change, as the profit rate varies, of the technical parameters; it is argued that this inequality can be used to construct functions that order the eligible techniques. Finally, it is argued that the characteristic functions can embody specific, nontechnical relations, so that a “technology” should be broadly interpreted as a collection of techniques of production plus “exogenous” relations that determine which techniques are to be included in the technology.

A decision-makin g model is presented in which (a) the apparent weight of evidence, to a juror deciding on a case, varies randomly over the population of potential jurors; (b) jurors decide for (against) the plaintiff or defendant if apparent weight is less (greater) than a decision criterion, which varies little over the population but may vary over cases, instructions to jurors, etc.; and (c) decision confidence increases as absolute difference between apparent weight and decision criterion increases, this increase being taken as linear for most of our presentation. We assume that the distribution of apparent weight is based on the exponential distribution and obtain estimates of mean apparent weight and decision criterion from four civil cases and two criminal cases. The effects of jury deliberation, jury size, the definition of "reasonable doubt," the introduction as evidence of a previous record of conviction, and instructions to disregard such evidence are described in terms of the parameter estimates. Finally, the theoretical relationship between decision frequency and confidence is discussed, and a measure is given of the difference between the subpopulations of jurors voting "for" and "against." It is shown that this difference measure equals the area under a confidence-rating operating characteristic curve.

In duration, size, and form discrimination tasks, a visual noise mask was presented at variable delays after stimulus offset in order to interrupt processing and control the extent of processing time. Previous work (Thomas & Cantor, 1975) had suggested that both perceived duration and perceived nontemporal “information” might be expected to increase as processing time was extended. As predicted, accuracy in the discrimination of size of circles and form of non-sense figures was found to vary directly with stimulus duration (20, 50 msec) and mask delay interval (0, 30, 70, 110 msec). Differences in perceived duration between filled (forms or circles) and unfilled (blank) intervals were found to increase monotonically with increases in the mask delay interval, when non-sense forms, but not circles, were presented. Two hypotheses of visual masking (“integration” and “interruption”) are discussed. Within the context of the “integration” hypothesis, a model is proposed which predicts processing time as a function of stimulus duration, mask delay interval, and the interval between onset of the mask and termination of processing.

Five groups of fictitious case outlines were prepared about a plaintiff who sued a defendant for damages. Within each group of cases, we independently manipulated evidence about the apparent fault (here labeled the propensity to fault) in the plaintiffs conduct and in the defendant's conduct, as well as evidence about the severity of the harm. Subjects rated the responsibility of the plaintiff and the defendant for the harm and assessed the liability against the defendant. The data were consistent with a hierarchical model of identification and attributional processes in which propensity influences responsibility, which in turn, influences liability. Analyses based on a measure of relative responsibility suggested that the rule, liability should be proportional to fault, was an inadequate description of the data. This finding is discussed in the context of the legal doctrines of contributory and comparative negligence.

This article considers procedures for combining individual probability distributions that belong to some “family” into a “group” probability distribution that belongs to the same family. The procedures considered are Vincentizing, in which quantiles are averaged across distributions; generalized Vincentizing, in which the quantiles are transformed before averaging; and pooling based on the distribution function or the probability density function. Some of these results are applied to models of reaction time in psychological experiments.

This paper examines the changes over time in the spatial dispersion of facilities in a bounded one-dimensional habitat. Each facility produces a single good for a unique market area and demand for the good varies inversely with distance to the nearest facility and increases uniformly over time. Production and transportation cost functions are not assumed to be linear, and it is assumed that market areas are chosen so as to minimise the average cost of producing and transporting unit amount of the good. Conditions relating the demand function to the transportation cost function are given which are necessary and/or sufficient for the size of the market area to decrease over time. It is shown that if the market area has constant size, ‘balanced growth’ occurs if and only if the demand function is of the Pareto type. Finally, the relevance to this analysis of economies of scale is discussed.

Judgments of the apparent duration and size of visually presented circles vary directly with the duration and size of the presented stimuli. When the frequencies of stimulus duration (short vs. long) and stimulus area (small vs. large) are varied, perceived size and duration are directly related to the frequency of the lower attribute value (short or small). These data are compared to the predictions of different information-processing models. The model which accounts for the data best is one in which it is assumed that perceived size and perceived duration grow together over the course of time spent sampling size information, and that attribute frequency affects the rate of sampling and/or the point at which sampling stops.

A class of discrete-state probabilistic models is discussed that allow for the separate assessment of the effects of both self-regulatory processes, including predispositions, and interactive processes on the complementary, reciprocal, and reinforcing tendencies of observable responses. In most of these models, the two responses made at Time t + 1 by members of an interacting dyad are statistically independent, given the pair of responses made at Time t. For each model, estimable parameters are denned in terms of state transition probabilities and are labeled, for the most part, as measures of bias or of sensitivity to previous own and other behavior. The models are applied to data collected by other researchers on the self-fulfilling nature of social stereotypes, on aggression in a natural setting, and on parent-infant interactions, and the resulting parameter estimates are discussed. Possible applications of the models for as sessing the effects of small group interaction are also mentioned.

A general model for learning signal detection in a Yes-No task is considered in which (a) the decision criterion shifts upward and downward by equal steps, and (b) the probability that the criterion shifts on a trial depends on the stimulus-response pair on that trial. Conditions are given for this process to have a unique stationary distribution, and the behavior of the process, as the step-size decreases to zero, is studied. The special model where criterion shifts may occur only on error trials can account for the probability matching behavior and for the interaction between signal strength and signal probability typically observed when the payoff matrix is symmetrical. Further, when the shift probability is assumed to be an increasing function of the distance of the sensory input from the criterion, the stationary mean criterion values are less extreme than the values that yield probability matching. It is shown that the model provides a way of incorporating payoff matrix asymmetry. Finally, the standard error in the maximum likelihood parameter estimates is calculated and a statistic is proposed for discriminating the error-correcting model from the more general model.

An experiment in typing is described in which the visual spacing in the text and the amount of linguistic structure in the material are varied. The results show that average typing speed is decreased both by removing visual spaces from the text and by decreasing the amount of structure in the material. The data are interpreted as evidence that there is response grouping in a typist's output, and a model is stated in which this grouping is attributed to the operation of a response-unit scanner. More detailed analysis by means of this model suggests a picture of serial and parallel information processing to be an adequate representation of the conversion of text into type.

SUMMARY Given a sample from each of three populations, it is sometimes of interest to decide whether the distribution function of one of the populations is a linear mixture of the distribution functions of the other two populations. This paper discusses distribution free procedures for testing such a hypothesis.

The present study uses a modified Solomon's four groups design with an additional expectancy control group to assess artifacts associated with pretesting in the measurement of individual risk preferences. Pretesting induces a cautious bias in posttest scores with either group discussion or individual familiarization as the experimental treatment. Further analysis shows that individual familiarization induces a significant cautious shift and confirms the known result that group discussion induces a shift to risk. These three effects were found to be item specific. A comparison of the pretest scores of the experimental groups and the expectancy control group reveals that pretesting in anticipation of group activity reduces the extremity of pretest scores but has no effect on the mean. Finally, it is shown that unpretested individuals, who have discussed the items in groups, are more risky than individuals considering the items for the first time. The phenomenon of the risky shift was initially identified by Stoner (1961), who found that individuals in groups were willing to make decisions involving greater risks than the average of their initial risk preferences. The instrument used to measure risk preferences, the Choice Dilemmas Questionnaire, has been described elsewhere (Kogan & Wallach, 1964; Stoner, 1961; Wallach, Kogan, & Bern, 1962), and some of its limitations have been pointed out by Cartwright (1971). Here we propose to comment on Stoner's experimental design (see Table 1) in order to provide a rationale for using another design in studies of this nature. This design comprises an experimental condition in which there is a pretest, an experimental treatment and a posttest, and a control condition in which there is only a pretest and a posttest. In the pretests and posttests the subjects individually indicate their risk preferences, the average of which is denoted by XEl and XKx, respectively, for 'the experimental condition, and by X(;, and Xc.t for the control condition. In the experimental treat

The present study is largely concerned with the relation between reaction time and the temporal uncertainty of the signal. It is suggested that the appropriate measure of signal uncertainty is the conditional probability that the signal would be presented given that it has not been presented before. This conditional probability is called the expectancy function. It is assumed that the expectancy function influences the subject's state of readiness and this in turn influences reaction time; and ways of expressing these relations mathematically are discussed. It is shown that, with a suitable representation of subjective errors in time and probability estimation, a theory can be stated which accounts for the qualitative features of a variety of experimental data. The relevance of this theory to studies concerned with central intermittency is then discussed. It is argued that temporal uncertainty alone is insufficient to account for the increase in reaction time to the second of two closely spaced signals, both of which require a response. On the other hand, a model for the interaction of two responses is stated in which refractoriness in the central processes is not inevitable.

The notion of expectancy has often been used in explanations of the relationship between foreperiod variability and simple reaction time. Two interpretations of the notion are distinguished: one is that expectancy or expectancy level is a moment in time, and the other is that expectancy is a regular function of time. The latter interpretation is adopted and it is shown that if expectancy is defined as the conditional probability of signal occurrence, then average reaction time would be linearly related to mean foreperiod duration. It is argued that this result can serve as a basis for unifying apparently diverse explanations of the reaction time—foreperiod relationship. Experimental data are presented which are consistent with the view of expectancy proposed in this paper.

Two detection cum latency models are constructed by combining sets of plausible assumptions about latency with, in the first instance, the model of the. Theory of Signal Detection and, in the second instance, a general threshold model. The aim of this paper is to show that latency statistics can be used to provide sharp tests for distinguishing between the two models. The two statistics studied are the reaction time operating characteristic (RT-ROC) and the plot of average reaction time against response probability (RT-probability curve). It is shown that, under the first detection model, the RT-ROC lies below the ROC derived from detection rates except at the “yes-no” point, and the RT-probability curve is decreasing whereas, under the second model, the RT-ROC coincides with portions of the latter ROC, and decreasing RT-probability curves do not arise naturally. The effect of criterion variability on the ROC is discussed in detail and conditions are given under which the RT-ROC is equivalent to a ROC generated by variable criteria.

In recognition tasks where the stimuli vary along two or more dimensions, the question arises as to what strategy the subject uses in processing the information about the various stimulus attributes. Three strategies are discussed: parallel, serial and integrative processing. It is shown that each of these three strategies implies a relation among the distribution functions of three observable random variables. The problem is then to decide on the basis of three samples, one from each distribution, which one of the relations is most likely. Non-parametric statistics are defined which can be used to construct test functions for this decision problem, and a suggestion is made concerning the design of experiments which attempt to discriminate between these strategies.

When the Limiting Method is used to measure heat-pain threshold, the observed threshod has been shown to depend on the size of the stimulus increment used (Haslam, 1965). An experiment is reported here which repeats a finding of the experiment referred to above that the variability of threshold is relatively large when the stimulus increment is small. A statistical analysis of the data shows that the previously untested hypothesis that pain threshold is uniform over the population (Hardy, Wolff and Goodell, 1952) is a reasonable one. The psychological implications of threshold variability are discussed in the light of a theoretical model, and a criterion for an optimum interval in the assessment of heat-pain threshold is discussed.

A model developed by Cane (1956) for the study of relative thresholds is modified to apply to absolute thresholds. It is assumed that the fluctuation in the subject's sensation of a stimulus is uniformly distributed, and the model is used to estimate the threshold from data presented by several authors.

Two statistical models for the clustered firing of cortical neurones are discussed. The first model assumes that a neurone alternates between periods of inactivity and periods of hypersensitivity during which it fires. The second model assumes a definite causal relation between a spike and the succeeding one. Both models lead to a mixed exponential probability density function for the inter-spike interval. Estimates of the parameters of the second model are obtained from published data, and are used as a basis for discussing the descriptive potential of the model.