Simultaneous and successive presentations of single-featured and multi-featured visual forms: Implications for the parallel processing hypothesis

The parallel processing hypothesis predicts no difference in hit rate (HR) for identical forms presented simultaneously or successively. This was tested in two experiments differing only in the number of features distinguishing stimulus forms: (1) one feature (Landolt Cs); (2) multiple features (the graphemes A, T, U). Each experiment had three conditions: (1) single form, (2) four simultaneous forms, (3) four successive forms. The major finding was a lack of HR increase for four simultaneous Cs over one C. HRs for successive Cs and both multiple letter conditions sharply increased over the one form condition. Results call into question the level at which parallel processing occurs. Three decision models, all assuming perceptual independence, were tested. None fit all the data.     

Changes in studying abilities as perceived by students attending psychotherapy

In rehabilitative psychotherapy, the goal is to support and improve the person's working and studying capacity and to secure his/her staying in or entering the workforce. In this qualitative study, the aim was to describe the changes students experienced in their studying ability and the advancement of their studies as a result of the therapy process. The results of this study showed many kinds of positive changes in the psychological resources and studying ability of students participating in psychotherapy. The results also show that when psychotherapy is arranged with the aim to support the study process, good connections between psychotherapy, study tutoring and career guidance are needed.     

Texture perceived with the fingers

Relative assessments of 10 attributes commonly used to describe the texture of liquids on skin were obtained for 14 liquids of widely varying rheological properties. The results were analyzed to show that these judgments can be predicted accurately from the assessments of just three attributes, smoothness, thinness, and warmth. Smoothness was found to be closely related to the forces of contact lubrication, and could be predicted from measurements of coefficients of friction. Thinness was found to be closely related to viscous forces, consistent with other predictions of assessments of thickness and spreadability. Warmth was not studied further. The results show how careful definition of the stimulus on the skin’s surface can sharply simplify the interpretation of the psychophysical experiment.     

Temporal reproductions are influenced by an internal reference: Explaining the Vierordt effect

Several findings from duration perception literature suggest that when making decisions about time, participants rely on an internal reference memory for time rather than merely on the current physical stimuli. According to a recent account, such an internal reference is formed by a continuous dynamic updating process that integrates duration information from previous trials and the current trial. In the present work, we show how such a dynamic mechanism can account for the classical yet unresolved Vierordt effect, which refers to the overestimation of relatively short and the underestimation of relatively long temporal intervals. We conducted an experiment to examine this and related predictions by means of a temporal reproduction task. Specifically, participants were presented with two successive time intervals — a standard s with constant duration and a comparison c with variable duration. Instead of performing a comparison judgment, however, the participants were subsequently cued to reproduce one of the two presented stimuli. Reproductions were affected not only by the temporal position of the to-be-reproduced stimulus, but also by the stimuli presented on earlier trials. These results support the notion of a dynamically updated internal reference underlying our judgments about the time elapsed, which might also be the basis of the Vierordt effect.     

The differential salience of spatial information features in the geometric reproductions of young children

To assess the differential salience of geometric features embedded in spatial displays, 60 preschool children, 3 to 5 years old, were required to reconstruct a series of geometric displays. Each arrangement included the depiction of a topological feature, unconnectedness; a Euclidean feature, linearity; and a projective feature, orientation. Children built their reconstructions under two demand conditions. The reconstructions were scored for the number that preserved each of the different geometric features. Results from a mixed-design analysis of variance revealed main effects for age, demand condition, and geometric feature, as well as for several first-order interactions. Data indicated that the Euclidean feature was the most salient and most frequently preserved characteristic and that the topological and projective ones were more problematic. The findings were discussed as a contrast to Piagetian predictions.     

Searching for a perceived stare in the crowd

Gaze direction can be represented in terms not only of local-feature information (ie the location of the pupil in the eye socket), but also of an emergent property---whether the perceived gaze direction is straight or averted. To examine whether this emergent property is preferentially accessed when searching for an oddly directed gaze, we experimentally manipulated the local-feature information and the emergent property independently, in order to investigate the influences of both types of information on visual searches for an oddly directed gaze. We found that the primary determinant of search efficiency was not the local-feature information of eye region, but the emergent property--the perceived direction of the gaze. This finding is consistent with the idea that important social signals are recognised primarily by their emergent properties.     

Effects of internal clock and memory disorders on duration reproductions and duration productions in patients with Parkinson's disease

Patients with Parkinson's disease (PD) exhibit deficits in perceptual and motor timing as well as impairments in memory and attentional processes that are related to dysfunction of dopaminergic systems in the basal ganglia. The aim of the present study was to assess the relationships existing between impaired duration judgments and defective memory and attention in PD patients. We compared time performance of medicated PD patients and control subjects on a duration reproduction task that is highly memory-dependent, and on a duration production task that could reveal effects of changes in the speed of internal time-keeping mechanisms. Each task was performed in a control counting condition and in a condition requiring divided attention between the temporal task and a concurrent reading task. Moreover, PD patients and control subjects were assessed on memory and attention using a battery of neuropsychological tests. The results revealed that in the concurrent reading condition of the reproduction task, duration judgments tended to be more variable in PD patients than in control subjects. Moreover, variability of duration reproductions was correlated with both measures of memory and of disease severity. In the concurrent reading condition of the production task, duration judgments were significantly shorter in PD patients than in control subjects, and accuracy of duration productions was correlated with scores on sub-tests of short-term memory. The findings suggest that the administration of dopamine did not entirely remove the memory deficits in PD patients. Moreover, DA treatment would have abnormally accelerated the rate of the internal clock leading to shorter duration productions in PD patients. The whole results indicate that dopamine administration in patients might have overshadowed the slowing rate of the internal clock usually reported in non medicated PD patients, without entirely restoring all of the memory functions.     

Range effects in successive discrimination

In two sets of experiments we examined pigeons' discrimination performance with a visual flicker-rate continuum, using a conventional successive discrimination procedure. In the first experiment, responses during the intermediate stimulus value were never reinforced, while responses during stimuli on either end of the continuum were reinforced periodically. In the second experiment, responses during stimuli from one end of the continuum were never reinforced, while responses during stimuli from the other end of the continuum were reinforced periodically. Results from both experiments show that discrimination between unchanged positive and negative stimulus values is a function of the range over which the total stimulus set varies. These range effects are comparable to effects found in absolute judgment tasks in human and animal psychophysics. In addition, the range effects reported here are not due to channel capacity, but may depend instead on variability in judgment criteria.     

Eye-position signals in successive saccades

Accuracy of the eye-position signal (EPS) in successive-saccade conditions was examined by analyzing the subject’s performance in tracking his gaze by pointing with his unobservable hand in the dark. The size of constant error in manual pointing was found to increase with the number of the component saccades and to be inversely proportional to the size of the largest component saccade. The results are interpreted as showing that, in successive-saccade conditions, subjects are not able to use the sum of EPSs from each component saccade, but rather use only the EPS from the largest component saccade.     

On the independence of judged frequencies for items presented in successive lists*

In an experiment examining retroactive interference effects in a frequency-judging task, all Ss were presented with a list of words occurring varying numbers of times according to either a massed- or distributed-practive (MP or DP) schedule. They were then asked to judge how often each word had occurred. Following this, Ss were given one of four types of second tasks a second list with different items followed by a frequency-judging task for that list (Condition New): a second list with items repeated from the first list but with different frequencies for each item, while either maintaining items as either MP or DP items (Condition Same) or switching MP items to DP, and vice versa (Condition Reverse): followed by a frequency-judging task for the second-list frequencies only: or a puzzle task for the amount of time required for second-list presentation and judgment in the other conditions (Condition None). Finally, all Ss were asked to recall List 1 frequencies, List 2 frequencies were less discriminable in Conditions Same and Reverse than in Condition New. Recall of List 1 frequencies, however, was not different for these three groups, but was poorer than in List 2 frequency judgments were not independent of List 1 frequencies.     

Domain-specific perfectionism in intercollegiate athletes: Relationships with perceived competence and perceived importance in sport and school

ObjectivesTo examine the domain-specific nature of perfectionism in sport and school, and to examine potential links between domain-specific perceived competence, perceived importance (task value), and perfectionism in sport and school.Design and MethodA total of 255 male and female varsity student-athletes from a successful intercollegiate sport program completed domain-specific (i.e., sport and school) versions of Hewitt and Flett's (1991) Multidimensional Perfectionism Scale (HF-MPS). Participants also completed an inventory designed to assess perceived competence (PC) in sport versus school and perceived importance (PI) of success in sport versus school.ResultsExploratory factor analyses conducted on perfectionism data indicated that perfectionist orientations were organized around domain-specific as opposed to global perfectionist tendencies. Regression analyses indicated that PC was a significant predictor of domain-specific levels of self-oriented and socially prescribed perfectionism (ps < .05), and PI was a significant predictor of domain-specific levels of self-oriented, socially prescribed, and other-oriented perfectionism (ps < .001). A repeated-measures MANOVA revealed that student-athletes had significantly higher levels of perfectionism in sport than school (ps < .0001) across all three HF-MPS subscales.ConclusionResults reinforce the value of measuring perfectionism as a domain-specific (rather than global) personality disposition, and identify the potential role that perceived competence and perceived importance may play in the development of domain-specific perfectionism.     

Note on the least squares solution for the method of successive categories

The problem of estimation in the method of successive categories is reconsidered and a new least squares solution is obtained. An empirical comparison of this solution with Gulliksen's solution is presented.Preparation of this paper has been supported by the Quartermaster Food and Container Institute for the Armed Forces. Views or conclusions expressed herein are those of the author and do not necessarily reflect the views or indorsement of the Department of Defense.     

A general least squares solution for successive intervals

A general least squares solution for successive intervals is presented, along with iterative procedures for obtaining stimulus scale values, discriminal dispersions, and category boundaries. Because provisions for weighting were incorporated into the derivation, the solution may be applied without loss of rigor to the typical experimental matrix of incomplete data, i.e., to a data matrix with missing entries, as well as to the rarely occurring matrix of complete data. The use of weights also permits adjustments for variations in the reliability of estimates obtained from the data. The computational steps involved in the solution are enumerated, the amount of labor required comparing favorably with other procedures. A quick, yet accurate, graphical approximation suggested by the least squares derivation is also described.This research was jointly supported in part by Princeton University, the Office of Naval Research under contract N6onr-270-20, and the National Science Foundation under grant NSF G-642, and in part by Educational Testing Service.     

Relationship of perceived stress with depression: complete mediation by perceived control and anxiety in Iran and the United States

This study sought to clarify the importance and cross-cultural relevance of associations between generalized perceived stress and depression. Also tested was the hypothesis that perceived stress would correlate more strongly with anxiety than with depression, whereas control would be more predictive of depression than of anxiety. Relationships between perceived stress, anxiety, depression, and perceived control were examined in samples of Iranian (n = 191) and American (n = 197) undergraduates. Correlations among these variables were generally similar across the two societies. Perceived stress did predict anxiety better than depression, but perceptions of control predicted depression significantly better than anxiety only in the United States. Best fitting structural equation models revealed that anxiety and perceived control completely accounted for the linkage between perceived stress and depression in both societies. An equally acceptable and more parsimonious model described perceived stress as a consequence rather than as an antecedent of anxiety and perceived control. Structural equation models were essentially identical across the two cultures except that internal control displayed a significant negative relationship with anxiety only in Iran. This result seemed to disconfirm any possible suggestion that a supposedly individualistic process like internal control could have no noteworthy role within a presumably more collectivistic Muslim society like Iran. Overall, these data documented the importance of anxiety and perceived control in explaining the perceived stress-depression relationship cross-culturally and therefore questioned the usefulness of perceived stress in predicting depression. Whether this understanding of the stress-depression relationship deserves general acceptance will require additional studies that measure the frequency of stressful life events and that utilize a longitudinal design.     

Changes in perceived contrast,reaction time,and pattern-specific evoked potentials due to stimulus duration

Using patterned stimulation without luminance change, the authors manipulated the stimulus duration and measured three variables: the magnitude of contrast experience, simple reaction time, and the amplitude of pattern-specific visual evoked potentials. While contrast experience, measured by the scaling method, indicated no saturation below 85 msec, the other two variables saturated below 40 msec. The lower saturation value of the pattern-specific evoked potential is considered as the limit of the correlation between psychophysical measures and brain electric activity. This suprathreshold divergence can be seen as evidence that processes underlying the pattern-specific visual evoked potential components cannot be considered as mechanisms mediating subjective experience of spatial contrast.     

Testing the significance of the successive components in redundancy analysis

In this paper we study the interrelationships between two sets of data measured on the same subjects via redundancy analysis. We consider redundancy analysis from an inferential point of view. Under the hypothesis of multinormality, tests of significance are obtained for each successive redundancy component so that only the significant factors are retained for prediction purposes. An example illustrates the method. The authors would like to thank the Editor and the referees for their helpful comments. This research has been partly financed by NSERC (Canada).     

The interaction of perceived distance with the perceived direction of visual motion during movements of the eyes and the head

A horizontally moving target was followed by rotation of the eyes alone or by a lateral movement of the head. These movements resulted in the retinal displacement of a vertically moving target from its perceived path, the amplitude of which was determined by the phase and amplitude of the object motion and of the eye or head movements. In two experiments, we tested the prediction from our model of spatial motion (Swanston, Wade, & Day, 1987) that perceived distance interacts with compensation for head movements, but not with compensation-for eye movements with respect to a stationary head. In both experiments, when the vertically moving target was seen at a distance different from its physical distance, its perceived path was displaced relative to that seen when there was no error in pereived distance, or when it was pursued by eye movements alone. In a third experiment, simultaneous measurements of eye and head position during lateral head movements showed that errors in fixation were not sufficient to require modification of the retinal paths determined by the geometry of the observation conditions in Experiments 1 and 2.