Nonhomogeneous resolution of images of natural scenes

The aim of this research is to model and simulate the loss of visual resolution as a function of retinal eccentricity in the perception of natural scenes. The model of visual resolution is based on a space-variant low-pass filter, having a variable convolution kernel according to retinal eccentricity. The parameters of the model are computed from psychophysical measures of visual acuity as a function of retinal eccentricity. The implementation of the model allowed us to generate images of scenes with nonhomogeneous space-variant resolution, simulating the filtering executed by the eye. These scenes are used to test and optimise the model by means of experiments in static vision (through tachistoscopic presentations) and in dynamic vision where the resolution of the scene is computed, in real-time, as a function of the location of gaze.     

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One-sided nonparametric tests for ordinal data

Baumgartner, Weiss, and Schindler (1998) introduced a novel non-parametric test for the two-sample comparison that is superior to commonly used tests such as the Wilcoxon rank-sum test. A modification of the novel test statistic can be used for one-sided comparisons based on ordinal data. Such comparisons frequently occur in psychological research, and the Wilcoxon test is often recommended for their analysis. Here, the two tests were compared in a simulation study. According to this study the tests have a similar type I error rate, but the modified Baumgartner-Weiss-Schindler test is more powerful than the Wilcoxon test.     

Rewarded remembering: dissociations between self-rated motivation and memory performance

People often claim that they perform better in memory performance tasks when they are more motivated. However, past research has shown minimal effects of motivation on memory performance when factors contributing to item-specific biases during encoding and retrieval are taken into account. The purpose of the present study was to examine the generality of this apparent dissociation by using more sensitive measures of experienced motivation and memory performance. Extrinsic motivation was manipulated through competition instructions, and subjective ratings of intrinsic and extrinsic motivation were obtained before and after study instructions. Participants studied a series of words, and memory performance was assessed by content recall (Experiment 1) and source recall (Experiment 2). Both experiments showed dissociation between subjective ratings of extrinsic motivation and actual memory performance, so that competition increased self-rated extrinsic motivation but had no effects on memory performance, including source recall. Inconsistent with most people's expectations, the findings suggest that extrinsic motivation has minimal effects on memory performance.     

Parenting, achievement strategies and satisfaction in ice hockey

The aim of this study is to understand adolescent players' satisfaction as a function of parenting styles, players' achievement strategies, and their norm breaking behavior. Finnish 14- and 16-year-old ice-hockey players (n=1018) completed a questionnaire measuring their achievement strategies (SAQ; Nurmi, Salmela--Aro & Haavisto, 1995 b), as well as scales of norm breaking and satisfaction, prepared for the present study. The parents (n=979) filled in scales measuring their parenting styles (CRPR; Pulkkinen, 1996) and attitudes towards norm breaking. Results revealed that players from authoritative families who showed a high level of mastery-orientation expressed high satisfaction in playing ice hockey. Results also showed negative associations between authoritative parenting and both task irrelevant and norm breaking behavior. Parents with parental stress and those with authoritarian parenting styles showed positive attitudes to norm breaking behavior, and players from authoritarian and parental stress homes showed norm breaking behavior in ice hockey. There was no association between norm breaking behavior and player satisfaction. Our results contribute to the planning of a coaching system that serves more educational and developmental purposes, and that encourages the desire to play ice hockey as a hobby.     

Rapid serial naming: relations between different stimuli and neuropsychological factors

We report two studies on rapid serial naming (RSN). Study 1 addressed the relations among RSN tasks comprising different stimuli. Separate components for RSN of alphanumeric and non-alphanumeric stimuli, as well as for tasks in which the stimuli alternated between categories were identified. In Study 2, phonological skills, processing speed, motor dexterity, and verbal fluency were found to explain RSN performance. The studies indicate: (1) that RSN tasks vary in their properties according to the stimuli used and according to the way the tasks are arranged, and (2) that RSN tasks are multi-componented.     

Detection of sound rise time by adults with dyslexia

Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia or compensated dyslexia and a control group performed a detection task with sound pairs of different rise times. Results showed that the participants with dyslexia differed from the control group in rise time detection and a correlation was found between rise time detection and reading and phonological skills. A subgroup of participants with lower sensitivity to rise time detection characterized by low accuracy in syllable-level phonological skills was found within the dyslexic group. Short stimuli containing only one rise time produced associations with phonological skills and reading, even in a language where the perception of rise time contrasts are not crucial for the signaling of phonemic contrast.     

Inhibition of return in children with Tourette's syndrome and comorbid forms: a preliminary study.

BACKGROUND: This study investigated the nature and functioning of the visual-spatial inhibition of return (IOR) phenomenon in children with "pure" Tourette's syndrome (TS), and those with comorbid forms of TS. METHOD: Children with TS-only and "TS + comorbid" (TS + ADHD +/- OCD) and matched controls performed the inhibition of return (IOR) task, which involved responding to left and right visual targets appearing on a computer screen that were preceded by congruent or incongruent exogenous visual cues. RESULTS: The TS-only group performed similarly on the IOR task to the controls. When the TS-only group was subdivided into children with mild and severe TS symptoms, a post hoc comparison between the controls and severe TS symptom children revealed that these TS children had a reduced magnitude of IOR for targets appearing in the right visual field. The comparison between the TS + comorbid and controls revealed an atypical IOR pattern for the TS + comorbid group. They displayed a loss of normal facilitatory and inhibitory effects for right visual field targets. CONCLUSIONS: The findings suggest abnormalities in attentional "disengage" and "move" mechanisms in TS when directing attention to the right visual field, which may reflect left posterior parietal, superior colliculus, and midbrain pathology.