The effects of figurai shape on the perception of area

It was hypothesized that figures of equal area and different shapes are perceived as differing in area and that these apparent differences in area are due to the interaction of certain shape variables. Thirty figures were presented to 45 Ss for paired comparisons. Forty-five sets of 30 Choice scores were calculated. The performance of each S was tested for consistency by the Method of Circular Triads (p>.01). A Coefficient of Agreement (u) indicated that the Ss agreed among themselves (p>.01). Fifteen Ss were tested twice for test-retest reliability (p>.01). The 45 sets of Choice scores were then converted to rank values and averaged over all Ss. The mean rank values of the 30 figures were treated with the two-way analysis of variance by ranks to determine the significance of the differences among them (p>.01). A Coefficient of Concordance (W) was calculated on the 45 sets of rank values to support the results of the analysis of variance (p>.01). Subsequently, the 30 mean rank values were treated as the dependent variable in a multiple correlation (R) with the shape variables as the independent variables (p>.01). The apparent area of the figures was found to vary inversely with perimeter, number of turns, breadth, and external area.     

The effects of base rates and individuating information on judgments about another person

Past research suggests that in judging a person's category membership, people largely ignore the population frequency of membership in the category (base rates) in favor of individuating information about the particular person. This study tested the hypothesis that base rates will be utilized to the extent that the usefulness of the individuating information for diagnosing category membership is diminished. Subjects were given problems in which both base rates of membership in each of two categories and individuating information about a target person were presented. Then, in each case, they were asked to assess the probability that the target person belonged to each category. In three sets of problems, the diagnostic usefulness of the individuating information (personality characteristics) was diminished by including individuating information that was either inconsistent or irrelevant, or by increasing the similarity of the two alternative membership categories. In a fourth set of problems, the individualistic information included consistent, relevant personal characteristics and the membership categories were dissimilar. As expected, base rates were used in each of the first three sets of problems but were ignored in the fourth set. The results were interpreted in terms of informational factors that induce a shift away from a habitual, spontaneous reliance on a source of information (e.g., personality traits) for which one has well-developed rules (e.g., intuitive personality theories), and toward a more controlled, deliberate mode of thinking wherein other sources of information (e.g., base rates) are attended to and incorporated into judgment through less frequently used rules (e.g., sampling rules).     

The effects of smoking and urinary pH on a detection task

Performance was measured in a detection task over a period of 50 min. Subjects were either non-smokers or smoked more than 15 cigarettes per day. No smoking was allowed during the task, but smokers were all asked to smoke a cigarette immediately before doing it. One hour previously, subjects had been given a double-blind dose of a substance which would shift the pH of their urine either upwards or downwards, by small amounts sufficient to affect the rate of renal excretion of nicotine in the smokers. The pH manipulation had no effect on the performance of the non-smokers, who improved steadily throughout the task. After some 40 min of performance, the deprived smokers showed less improvement than the non-smokers, and the smokers whose urine had been made acid improved less than those whose had been made alkaline. The results are interpreted as evidence for a phasic effect on performance of small degrees of nicotine deprivation, which has consequences for theories of nicotine dependence.     

The effect of uncertainty on the detection of frequency modulation at low modulation rates

Frequency modulation detection performance is compared in two conditions of stimulus variability. The data show that when the modulation rate is randomized within an experimental block, performance is somewhat poorer than when the modulation rate is fixed. The results are interpreted within the framework of a template matching model for modulation detection. They suggest that a template is acquired in part from experimental context and in part from a multistage template matching process.     

Motor and cognitive interference effects on unimanual tapping rates

Experiments conducted on both normal and disordered populations have led to the hypothesis that the left hemisphere's specialization for language results from its control over motor activities. This control is reflected in the lateralized disruption of manual activity during cerebral time-sharing tasks. Recent studies have challenged this hypothesis, stating that the interference effects reflect both cognitive and motor mechanisms in the left hemisphere. This experiment investigates whether the left hemisphere's control over speech involves both of these components or is purely motor. The question was examined by measuring the effect of concurrent hemispheric activity on single-finger tapping rates. Forty subjects tapped under two conditions: speaking and listening. The data show there may be both motor and cognitive mechanisms involved in left-hemisphere control.     

The effects of orientation on detection and identification of facial expressions of emotion

Signal detection procedures were used to examine the ability of participants to detect and label facial expressions of emotion in an upright or inverted orientation when the faces were rapid videotaped presentations. The detection and identification of facial expressions were remarkably accurate. In the upright orientation, the A′ measure of sensitivity was above .9 for detection and identification of all six facial expressions of emotion. Sensitivity to inverted expressions was diminished for all emotions; however, the extent of the decline in sensitivity depended upon the specific facial expression. If the expression was difficult to detect or label in the upright orientation, the sensitivity score was lower in the inverted orientation. An assessment of the errors made in the detection and labelling process allowed a demonstration of the specific facial expressions that were confused in either the upright or inverted orientation. The assessment of sensitivity and analysis of the errors suggests that the nature of perceptual processing of some, but not all, facial expressions is changed by inversion.     

Neighbourhood effects on error rates in speech production

Models of speech production differ on whether phonological neighbourhoods should affect processing, and on whether effects should be facilitatory or inhibitory. Inhibitory effects of large neighbourhoods have been argued to underlie apparent anti-frequency effects, whereby high-frequency default features are more prone to mispronunciation errors than low-frequency nondefault features. Data from the original SLIPs experiments that found apparent anti-frequency effects are analysed for neighbourhood effects. Effects are facilitatory: errors are significantly less likely for words with large numbers of neighbours that share the characteristic that is being primed for error ("friends"). Words in the neighbourhood that do not share the target characteristic ("enemies") have little effect on error rates. Neighbourhood effects do not underlie the apparent anti-frequency effects. Implications for models of speech production are discussed.     

The effects of legislative reform on civil commitment admission rates: A critical analysis

Many jurisdictions across North America have revised their statutes pertaining to the criteria for civil commitment with the legislative intent to either increase or decrease the use of involuntary hospitalization. The impact of these revised statutes has been examined in many jurisdictions, but there has been no consensus regarding their effectiveness in changing the rates of involuntary admissions. The present article reviews the literature from a methodological perspective, comparing the differing analyses, results and interpretations. When the legislative revision has sought to expand medical prerogative, results indicate a sustained increase in civil commitments. When legislation has aimed at limiting medical discretion, there was an immediate decline in civil commitment rates, but a subsequent increase in the period following the initial post-reform declines. These results are discussed in terms of readmission trends, deinstitutionalization, and the possible reaction of mental health professionals who perceive legislation as an unnecessary constraint in the treatment of the mentally ill.     

The effects of reordering the response categories on the area under the ROC

The area under the rating ROC can be a useful index of stimulus discriminability. It has the advantage that few assumptions must be made about the underlying distributions of signal and noise. One of the assumptions that must be made is the order of the subject’s response scale. A procedure is outlined for determining the order of the response scale actually used by the subject, and some of the implications of reordering the scale used in analysis are discussed. Results of computer simulation of the effects of varying some important experimental parameters are presented.     

The effects of emotional stimuli on target detection: indirect and direct resource costs

The present study was designed to explore the performance costs of negative emotional stimuli in a vigilance task. Forty participants (20 women) performed a vigilance task in two conditions: one with task-irrelevant negative-arousing pictures and one with task-irrelevant neutral pictures. In addition to performance, we measured subjective state (energetic arousal, tense arousal, task-related and task-unrelated thoughts) and frontal cerebral activity with near infrared spectroscopy. Overall performance in the negative picture condition was lower than in the neutral picture condition and the negative picture condition had elevated levels of energetic arousal, tense arousal and task-related thoughts. Moreover, there was a significant relationship between the impact of the negative pictures on tense arousal and task-related thoughts and the impact of the negative pictures on performance (in comparison to the neutral picture stimuli task). These results provide support for indirect cost models of negative emotional stimuli on target detection performance.     

The effects of aging on reaction time in a signal detection task

The effects of aging on response time are examined in 2 simple signal detection tasks with young and older subjects (age 60 years and older). Older subjects were generally slower than young subjects, and standard Brinley plot analyses of response times showed typical results: slopes greater than 1 and (mostly) negative intercepts. R. Ratcliff, D. Spieler, and G. McKoon (2000) showed that the slopes of Brinley plots measure the relative standard deviations of the distributions of response times for older versus young subjects. Applying R. Ratcliff's (1978) diffusion model to fit the response times, their distributions, and response accuracy, it was found that the larger spread in older subjects' response times and their slowness relative to young subjects comes from a 50-ms slowing of the nondecision components of response time and more from conservative settings of response criteria.     

The effects of syntactic structure on letter detection in adjacent function words

In the present study, we examined letter detection in very frequent function-word sequences. It has been claimed that such sequences are processed in a unitized manner, thus preempting access to their constituent letters. In contrast, we showed that letter detection in the words for and the (1) was no more difficult when the words appeared in adjacent locations in a sentence (familiar) than when they appeared apart (less familiar sequence) and (2) was contingent upon the words' syntactic roles within the phrase. Thus, letter detection in for was easier when the sequence was separated by a clause boundary than when the words were part of the same clause. The advantage derived from clause separation was strongest when a comma divided clauses. These results challenge the unitization account of the "missing-letter" effect in common phrases and support a position where this phenomenon is seen to reflect the extraction of phrase structure during reading.     

The effects of coping primes on responses to messages about disease detection behaviors

Abstract

This study examined the influence of coping primes on responses to subsequent messages that encouraged the performance of health behaviors. It was hypothesized that the addition of a coping prime prior to a message encouraging a disease detection behavior would increase the likelihood that the message would be attended to and that persuasion would occur. To test this hypothesis participants were required to read a coping or neutral prime. Coping primes were statements that indicated that the upcoming message would present information about a behavior, and that this behavior would help them deal with a serious health threat. After reading the prime participants were presented with a message encouraging the performance of a health promotion or a disease detection behavior. The primary measures recorded were the participants' cognitive responses to the message, and their attitudes about the behavior. The results supported the hypothesis.     

On the effects of food deprivation and component reinforcer rates on multiple-schedule performance

Six pigeons were used to investigate the effects of varying body weight and component reinforcer rates in two-component multiple variable-interval variable-interval schedules. In Parts 1 and 3 of the experiment, unequal component reinforcer rates were arranged, and body weights were respectively increased and decreased. At 80% ad lib weight, response-rate ratios were closer to unity than reinforcer-rate ratios, but at 100% or more of ad lib weight, response-rate ratios generally equaled reinforcer-rate ratios. In Part 2, component reinforcer-rate ratios were varied over five conditions with the subjects maintained at 100% or more of their ad lib weights, and response-rate ratios matched reinforcer-rate ratios. The data thus support the empirical finding that response allocation in multiple schedules is a function of deprivation. Although this qualitative result is predicted by three models of multiple-schedule performance, only a model that assumes no direct component interaction adequately describes the data.     

The effects of reinforcer choice on rates of challenging behavior and free operant responding in individuals with severe disabilities

A multielement design was used to evaluate the effects of three reinforcement conditions on the free-operant and challenging responses of two individuals with severe disabilities. Preference assessments identified three stimuli that could function as reinforcers for each participant. Reinforcers were delivered on a variable ratio schedule for a free-operant response. In the participant-selected condition, each reinforcer delivery consisted of placing an array of three different stimuli in front of the participant, who was allowed to select one. In the constant condition, each reinforcer delivery consisted of placing an array of three identical stimuli in front of the participant. Within each session the three stimuli were held constant, but varied across sessions. In the experimenter-selected condition, each reinforcer delivery consisted of an array of three identical stimuli being placed in front of the participant. Within each session, the three stimuli were presented in an order predetermined by the experimenter such that, on average, each stimulus was available every third reinforcer delivery. For both individuals, the participant-selected condition resulted in lower average rates of challenging responses and slightly higher average free-operant response rates. No differences in responding were noted between the constant condition and the experimenter-selected condition. © 1998 John Wiley & Sons, Ltd.     

The effects of figure/ground, perceived area, and target saliency on the luminosity threshold

Observers adjusted the luminance of a target region until it began to appear self-luminous, or glowing. In Experiment 1, the target was either a face-shaped region (figure) or a non-face-shaped region (ground) of identical area that appeared to be the face's background. In Experiment 2, the target was a square or a trapezoid of identical area that appeared as a tilted rectangle. In Experiment 3, the target was a square surrounded by square, circular, or diamond-shaped elements. Targets that (1) were perceived as figures, (2) were phenomenally small in area, or (3) did not group well with other elements in the array because of shape appeared self-luminous at significantly lower luminance levels. These results indicate that like lightness perception, the luminosity threshold is influenced by perceptual organization and is not based on low-level retinal processes alone.     

Differential effects of fixed- and variable-time feedback on production rates of elementary school children

The performance of 26 third-grade students who worked on individual weekly academic tasks was compared under fixed- and variable-time "home reports". During fixed-time home reports, each student was given a report to take home on Friday that indicated the quantity of work the student had completed that week, contained comments concerning the quality of the work, and had a space for parental remarks and signature. The same report was given during the variable-time reports, except that seven to nine students were randomly selected each day to receive a home report. During variable-time reporting, students completed more assignments and completed assignments on a greater percentage of available workdays than during fixed-time reporting. The teachers' preference for the variable-time reporting was one additional advantage for the variable system.     

Paradoxical effects of base rates and representation in category learning

The inverse base rate effect (IBRE) continues to be a puzzling case of decision making on the basis of conflicting information in human category learning. After being trained via feedback over trials to assign combinations of cues to high- and low-frequency categories, participants tend to respond with the low-frequency category to an otherwise perfectly conflicting pair of test cues, contrary to the category base rates. Our Experiment 1 demonstrated that decision making on the basis of an explicit summary of the cue-outcome and outcome base rate information from the standard learning task does not result in the effect. The remaining experimental conditions evaluated the necessary and sufficient conditions for the effect by systematically exploring experimental deviations between the standard learning task and the pure decision-making task. In partial disagreement with both recent theoretical accounts of the effect, these experiments indicate that asymmetric outcome representation and profound base rate neglect are individually necessary and jointly sufficient conditions. Broader theoretical implications are discussed.