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In a prospective and intraindividually comparative study, we investigated visual performance after implantation of two multifocal intraocular lenses. Eight patients received the ReSTOR (Alcon) bilaterally, and eight patients received the Tecnis ZM900 (AMO). The nondominant eye of each patient was trained based on the concept of perceptual learning using orientation discrimination of near-vertical bars. The fellow eye served as a control. After 3 h of training distributed over 2 weeks, the mean improvement of orientation discrimination in the trained eyes was 44%, which was significantly higher compared with the control eyes (9%). Moreover, contrast sensitivity and near vision under different contrast levels showed a significant benefit of training. These results support the concept of improving visual function by training after multifocal lens implantation. The superior function of the trained eyes was still present at the 6-month follow-up.

Results of three experimental studies (implemented in naturalistic kindergarten-settings) on short-term effects of social stress on concentration performance in young children are presented. In all 250 kindergarten-children were tested repeatedly with the Kaseler-Konzentrations-Aufgabe (KKA; Kasel-Concentration-Task for Children Aged 3-8 Years; test-duration: 6-7 minutes). In addition, after each KKA-test the children were asked about their subjective feelings of tiredness and of distractions during the test. In Study I 90 kindergarten-children were randomized to a standard individual test-setting, a triadic test-setting with another child observing the test child, and an individual test-setting within the noisy kindergarten group. Study II refers to 40 kindergarten-children tested individually and repeatedly in a silent standard setting, in a noisy setting with other children playing loudly outside, and in a noisy setting with other children singing very loudly in their group-rooms outside the testing-room. 120 kindergarten-children took part in Study III, in which test time and social setting (shortly after arrival in kindergarten, after joint breakfast, before and after joint lunch) were varied. In Study I results point at large negative effects of social stress on concentration performance. No effects of typical kindergarten noises on concentration were observed in Study II and Study III, with the exception of stress reactions on concentration in the after-joint-lunch kindergarten setting. Results point at good habituations to common social stress in kindergarten-children as well as specific strong stress reactions on concentration in social settings, including observers and noisy group-settings. Subjective ratings of distractions during testing and of tiredness after testing are not correlated with cognitive stress reactions, putting the competence of kindergarten-children to report verbally solid about their stress reactions in question.

Dargestellt werden die Ergebnisse aus drei feldexperimentellen Studien zu den kurzfristigen Effekten von sozialem Stress auf die Konzentrationsleistungen von Kindern. An den Experimenten waren insgesamt 250 Kindergartenkinder beteiligt, deren kurzfristige Konzentrationsleistungen wiederholt mit der Kaseler-Konzentrations-Aufgabe für 3- bis 8-Jährige (KKA) erfasst wurden. Ergänzend wurden die Kinder direkt nach der Konzentrationstestung zu subjektiv erlebten Störungen und ihrer aktuellen Müdigkeit befragt. Nach dem Zufall wurden 90 Kindergartenkinder in Studie I einer Standard-Einzeltestung, einer triadischen Testsituation mit einem anderen Kind als Beobachter und einer individuellen Testsituation in der lauten Kindergartengruppe zugewiesen. In Studie II wurden 40 Kindergartenkinder individuell wiederholt in einer ruhigen Standard-Testsituation, unter Lärmbedingungen durch außerhalb des Testraums frei spielende Kinder und unter Geräuschbedingungen durch lautes Singen anderer Kinder in ihren Gruppenräumen getestet. An Studie III waren 120 Kindergartenkinder beteiligt, die kurz nach der Kindergarten-Ankunft, nach dem gemeinsamen Frühstück sowie vor und nach dem gemeinsamen Mittagessen untersucht wurden. Die Ergebnisse weisen auf sehr starke negative Effekte von direktem sozialen Stress (Studie I) auf die Konzentrationsleistungen. Mit Ausnahme mittlerer Stressreaktionen bei der Testung nach dem gemeinsamen Mittagessen waren für die typischen Kindergarten-Geräuschbedingungen in Studie III und auch in Studie II keine negativen Einflüsse auf die Konzentration zu beobachten. Damit weisen die Befunde bei Kindergartenkindern auf solide Habituationen an den in Kindergärten üblichen sozialen Stress und auf starke spezifische Stressreaktionen (Konzentrationsabfälle) in sozialen Situationen mit Beobachtern und lauten Gruppenbedingungen. Die subjektiven Belastungseinschätzungen weichen deutlich von den objektiven Testbefunden ab, was die Fähigkeiten von Kindergartenkindern in Frage stellt, sprachlich valide über ihre Stressreaktionen zu berichten. Schlagwörter sozialer Stress - Stressreaktionen - Konzentration - selektive Aufmerksamkeit - Vorschulkinder, Results of three experimental studies (implemented in naturalistic kindergarten-settings) on short-term effects of social stress on concentration performance in young children are presented. In all 250 kindergarten-children were tested repeatedly with the Kaseler-Konzentrations-Aufgabe (KKA; Kasel-Concentration-Task for Children Aged 3-8 Years; test-duration: 6-7 minutes). In addition, after each KKA-test the children were asked about their subjective feelings of tiredness and of distractions during the test. In Study I 90 kindergarten-children were randomized to a standard individual test-setting, a triadic test-setting with another child observing the test child, and an individual test-setting within the noisy kindergarten group. Study II refers to 40 kindergartenchildren tested individually and repeatedly in a silent standard setting, in a noisy setting with other children playing loudly outside, and in a noisy setting with other children singing very loudly in their group-rooms outside the testing-room. 120 kindergarten-children took part in Study III, in which test time and social setting (shortly after arrival in kindergarten, after joint breakfast, before and after joint lunch) were varied. In Study I results point at large negative effects of social stress on concentration performance. No effects of typical kindergarten noises on concentration were observed in Study II and Study III, with the exception of stress reactions on concentration in the after-joint-lunch kindergarten setting. Results point at good habituations to common social stress in kindergarten-children as well as specific strong stress reactions on concentration in social settings, including observers and noisy group-settings. Subjective ratings of distractions during testing and of tiredness after testing are not correlated with cognitive stress reactions, putting the competence of kindergarten-children to report verbally solid about their stress reactions in question. Keywords social stress - stress reactions - concentration - selective attention - preschool aged children

The aim of this study was to provide a description of the spatial distortions and temporal instability in amblyopic vision, and to attempt to define a cortical substrate of the spatial distortions in strabismic amblyopia.The perceptual distortions and instabilities occurring in amblyopic vision were investigated psychophysically, by asking 17 subjects to describe and sketch their percepts. This was then visualised with an animated computer programme and validated by the subjects. In a second experiment, the cortical responses of normal observers to patterns corresponding to the spatial distortions reported by amblyopic subjects were investigated using functional magnetic resonance imaging.Spatial distortions were more marked in strabismic than in anisometropic amblyopes or in strabismic subjects with alternating fixation. Temporal instability occurred mainly in strabismic amblyopes and affected mainly patterns with higher spatial frequencies. Experiments with functional magnetic resonance imaging showed that the patterns with the highest spatial distortions yield increased activation in the primary visual cortex of normally-sighted observers.The results of the imaging experiment suggest that the occurrence of spatial distortions might explain the higher activation in the primary visual cortex of some amblyopic subjects. The occurrence of temporal instability in strabismic amblyopia suggests an involvement of higher-order, extrastriate visual areas of the dorsal, "where" visual pathway in amblyopia, in addition to the known deficits in the ventral, "what" visual pathway.

The influence of social rank and social environment on visual discrimination learning of small groups of Nigerian dwarf goats (Capra hircus, n = 79) was studied using a computer-controlled learning device integrated in the animals' home pen. The experiment was divided into three sections (LE1, LE1 u, LE2; each 14d). In LE1 the goats learned a discrimination task in a socially stable environment. In LE1u animals were mixed and relocated to another pen and given the same task as in LE1. In LE2 the animals were mixed and relocated again and given a new discrimination task. We used drinking water as a primary reinforcer. The rank category of the goats were analysed as alpha, omega or middle ranking for each section of the experiment. The rank category had an influence on daily learning success (percentage of successful trials per day) only in LE1 u. Daily learning success decreased after mixing and relocation of the animals in LE1 u and LE2 compared to LE1. That resulted in an undersupply of drinking water on the first day of both these tasks. We discuss social stress induced by agonistic interactions after mixing as a reason for that decline. The absolute learning performance (trials to reach the learning criterion) of the omega animals was lower in LE2 compared to the other rank categories. Furthermore, their absolute learning performance was lower in LE2 compared to LE1. For future application of similar automated learning devices in animal husbandry, we recommend against the combination of management routines like mixing and relocation with changes in the learning task because of the negative effects on learning performance, particularly of the omega animals.

In the present study, functional neuroanatomy of the frontal lobe and limbic system could be uncovered as emotion processing neural substrates. fMRI was used to test the influence of induced emotions on a non-affective, attention-demanding, cognitive task.6 Psychopaths versus 7 controls were analyzed by fMRI with a simon-paradigm after emotion induction.Emotion induction differentially influenced cortical activation patterns in emotion related brain areas like the amygdala and the medial prefrontal cortex.Structural-morphological neural areas of emotion regulation in "psychopathy" show variant activation patterns in fMRI. The neural basis of emotional impairment could be a dysfunctional medial prefrontal cortex and amygdala.

The influence of emotional contents on brain activation was examined using functional magnetic resonance tomography (fMRT).Aquiring 100 EPI-measurements of the whole brain, series of positive and negative pictures from the International Affective Picture System (IAPS) were shown to eight depressed males and to healthy controls.In depression, there was an overactivation in hippocampal area during positive stimulation, whereas an overactivation of amygdala, orbital and prefrontal regions was seen during negative stimulation.These results emphasize the importance of functional interaction between the neural network associated with emotion. We could show that depression is connected to dysregulation and disturbed functional connectivity during emotional processing.

The aim of this study was to validate and standardise a number of pictures from the International Affective Picture System from Lang (CSEA-NIMH, 1999; Lang et al., 1999) relative to arousal and valence in 57 boys and 63 girls aged between six and twelve years.18 pictures with six positive, six negative and six neutral stimuli were presented to children aged between six and twelve years. The children had to rate the pictures with regard to the dimensions valence and arousal using the Self-Assessment-Manikin (SAM; Lang et at., 1980; Bradley et al., 1994), a visual rating scale.Children aged between six and twelve years were able to discriminate pictures and to rate them according to the two basic dimensions of emotion valence and arousal.Our selection of pictures from Lang's International Affective Picture System provides a number of standardised stimuli, which are suitable for affect induction for example in psychophysiological and neuroimaging studies in the age group of children between six and twelve years.

The clinical assessment of vision by means of optotypes does by no means test just two-point resolution, since a correct naming of the letters or digits requires a preceding visual object recognition. Cortical lesions can massively deteriorate vision up to a "Seelenblindheit" in spite of intact optics and retina. There are different processing levels involved in the analysis which can be individually defective, leading to disorders from visual indiscrimination to agnosia or anomia.

To evaluate the comparability between the well-established Sheridan-Gardiner test (SGT) and a new type of visual acuity test, called the Räder test (RT = broken wheel test) in pre-school children, and to compare test durations of these infant visual acuity tests.The RT consists of 16 cards with visus values of 0.16, 0.2, 0.25, 0.3, 0.5, 0.6, 0.8 and 1.0. One pair of cards depicting a car is used for testing. On one of the cards the car has intact wheels, on the other the wheels are incomplete, symbolized by a Landolt ring. The child must indicate, at a viewing distance of 3 meters, which of the wheels is incomplete. The SGT consists of seven visus plates: 5/60, 5/36, 5/24, 5/18, 5/12, 5/9 and 5/6. Each level is tested with one letter and can be repeated by the presentation of a further letter (A, H, O, T, U, V, X). The examination distance is 5 meters. The child must indicate, with reference to a card depicting all seven symbols, which letter the examiner is showing. The SGT and RT were performed in a randomized cross-over sequence in 30 children (20male, 10 female) of pre-school age (from 2 years up to and including the age of 5 years, mean 3.4 years +/- 0.77 SD, median 3.0 years). In all cases, the right eye was examined first. Examination duration was assessed for each acuity test, and for each eye separately with a stopwatch. The instruction time was not considered. The possible visual acuity values of both bests were replaced by a unified scale of visual acuity levels (ranging from 1 to 10). A difference of at least two levels was considered as relevant. The results were compared by means of the sign test at a significance level of 0.05.In particular, for higher visual acuity levels there were considerable differences, with SGT generally showing better results than RT: in 11 of 29 children, in both eyes RT values turned out to be at least 2 lines better than those obtained with SGT. The contrary situation, i. e., favoring SGT by more than 2 lines compared to RT, never occurred. According to the sign test, these differences were significant (p0.001). SGT revealed also clearly better visual acuity levels in those 22 children out of the 30, who exhibited differences by 2 lines or more in at least one eye (p0.001). The examination procedure with RT revealed problems in making the required directional decisions, especially between 2 and 4 years of age. This might interfere with the test interpretation and lead to distortion of the RT results. Total examination duration did not differ considerably between SGT (1.6 to 5.8 minutes, median 3.0 minutes) and RT (1.6 to 9.4 minutes, median 4.6 minutes), respectively.The Sheridan-Gardiner test generally shows better results than the new Räder (RT = broken wheel) test in pre-school children. Problems in making the required directional decisions may interfere with RT in this age group.

It has been suggested that training in temporal processing may significantly improve language processing and reading skills. However, improvement effects of training on language impairment or dyslexia have not been proven so far. In the present study a temporal processing training was evaluated.The participants of the present study were 42 children (5th graders) of a special school for children with reading and spelling problems. Children of one class (n = 21) were assigned to a training group (n = 21), the other class to a control group. Children in the training group took part in a training program consisting of auditory and visual order threshold and sound localisation tasks, over a period of eight weeks. We determined the order thresholds, sound localisation ability and reading and spelling performance of all children before and after the training period. Six months later all subjects were re-tested.Auditory and visual order thresholds decreased significantly more in the training group than in the control group. However, these changes were not accompanied by improvements in reading or spelling skills.In the present study no training effects on reading and writing performance were observed by using a program including temporal processing tasks. It is questionable whether training programs of temporal processing are useful methods in therapy of dyslexic children.

We aimed to test children with developmental dyslexia for possible alterations of their spatial and visuoperceptual ability.A total of 31 children with developmental dyslexia were included in the study. All children underwent a complete ophthalmological and orthoptic examination. Neuropsychological testing was performed using the Visual Object and Space Perception Battery (VOSP) and the subtest "Gestalt Closure" of the Kaufman Assessment Battery for children. Even though the VOSP is validated and standardized for adults, no normal values for children exist thus far. Therefore, a sex- and age-matched control group was tested. In addition, the parents of the dyslectic children completed the Child Behavior Checklist for Ages 4-18 (CBCL/4-18).All children presented normal ophthalmological and orthoptic findings. Performance in the VOSP subtests "progressive silhouettes test'" and "number location" was significantly reduced in dyslectic children when compared to controls ( p0.0003 and p0.046, respectively). There was also a tendency towards lower values in the subtest "position discrimination" ( p=0.07). In the other subtests no significant difference between dyslectic children and controls was observed. The results of the subtest "Gestalt Closure" of the K-ABC and the CBCL/4-18 were within normal ranges.The study demonstrates that developmental dyslexia is not based on ocular deficits, but indicates possible disturbances of visual-spatial cognition and visual-spatial perception in dyslectic children.

Commonly, coherence and correlation are used to describe interrelations between EEG signals. But, on this basis, the investigation of causality or direction of interrelations is not possible. The general idea of causality between two signals may be expressed in terms of upgrading the predictability of one signal bye the knowledge of the past of the other signal. The best established approach in this context is the so-called Granger causality. The study present an adaptive estimation of Granger causality, which allows to detect dynamic causal relations within time intervals of less 100 ms. The time-variant Granger causality is applied to EEG data of the Stroop task. It could be shown, that conflict situation generates a dense web of directed interactions from posterior to anterior cortical areas.

Deficits in vigilance/sustained attention of schizophrenic subjects have been a main topic of neuropsychological schizophrenia research for many years. The degraded stimulus Continuous Performance Test (ds-CPT) is the standard paradigm for measuring vigilance. Measurement of vigilance requires the observation of the course of perceptual sensitivity over time. The present review shows that from a theoretical point of view it is possible to show vigilance deficits (as a decrease of sensitivity) with the ds-CPT if certain conditions are given. However, only in a few schizophrenia studies the course of sensitivity over time was evaluated, while in most studies merely the level of sensitivity was analysed. Results presented in this review suggest that level and course of sensitivity are largely independent variables. Vigilance can be operationalised adequately only when considering the course of sensitivity over time. Therefore there still is a considerable need for research on the meaning of vigilance deficits for manifestation, course and treatment of schizophrenia.

Two experiments investigated the multicomponent theory of emotion intensity proposed by Frijda, Ortony, Sonnemans, and Clore (1992) in the case of surprise and compared it with the more traditional "feeling element" approach to emotion intensity. In both experiments the participants performed a choice reaction time task for a certain number of trials. In the last trial they were surprised by an unexpected change of appearance of the stimuli. In Experiment 1 the change concerned either an action-relevant or an action-irrelevant, affectively neutral stimulus. In Experiment 2 the change concerned either an affectively positive or an affectively negative stimulus. Response delay in the surprise trial served as the index of the interruption of ongoing processes caused by surprise. Immediately after the surprise trial the participants completed a surprise intensity questionnaire that was an adaptation of the general emotion intensity questionnaire used by Sonnemans and Frijda (1994). In contrast to the findings of Sonnemans and Frijda (1994), the present findings were consistently better in line with the traditional feeling element approach to emotion intensity than with the multicomponent theory. Possible reasons for the failure to support the multicomponent theory of emotion intensity for the case of surprise are considered.

Previous research on face processing showed a developmental trend from analytic to holistic processing. This developmental trend was due to increasing knowledge about faces with increasing age. In contrast, research on object processing revealed that analytic processing could occur in any age group. The goal of the present study was to test to what extent objects that are familiar to children could also induce holistic processing and whether the processing depends on the orientation of the objects--as it is in face processing. Children (6 to 11 years) and adults were instructed to classify upright and inverted objects (birds and planes) into two categories. The construction of the categories allowed participants to categorize the objects either analytically or holistically. The results showed a developmental trend from analytic to holistic processing, regardless of the objects' orientation. These findings indicate parallels as well as differences in the development of face and object processing.

In order to investigate the hypothesis that language-impaired children also show deficits in memory, 110 language-impaired and 123 children showing no such impairments (average age 10;0 yrs.) were tested for verbal memory and selecting attention through a matching familiar figures test. As an additional measure, teachers assessed the children, using DSM criteria, for both general attentivenesse and attention deficit disorder. The results revealed significant differences between both groups concerning their ability to memorise word lists and difficulties resisting distractions. They also show a significantly diminished stability regarding the retention of memories. Furthermore, the ability to memorise has proved to be greatly independent of both selective attention and the rated attentiveness in class. It is therefore concluded that language-impaired children have difficulties in acquiring information as well as a limited capacity to memorise. These differences in ability to memorise between language-impaired children and children with no impairments are most likely attributable to the meta-cognitive competence of the child.

Partially sighted often experience problems in orientation in public areas. Individual visual aids can only be used with limitations. Improving light intensity and colour contrasts of timetables, information signs, direction symbols, etc. can provide remedies. Experimentally substantiated directives do not yet exist.Experiments were conducted in 231 partially sighted subjects (binocular vision0.3) diagnosed as experiencing dullness when watching the media, having maculopathies, glaucomas, or dystrophic alterations of the retina or choroid, and in 43 normal subjects to determine the subjective assessment of colour and light-intensity contrasts. The presented contrast patterns were Hartmann-characters as infield (3.3 degrees) with a rectangular surround (19.5 degrees x 14.3 degrees). Three experimental series were carried out in which subjects assigned 14 non-coloured/non-coloured contrasts, 35 non-coloured/colour contrasts and 30 colour/colour contrasts to any of the five assessment classes of extremely poor, poor, optimal, sharp, extremely sharp. The colour contrasts consisted of combinations of yellow, green, red, purple, blue, and non-coloured.For non-coloured/non-coloured, the subjects preferred positive contrasts (bright infield, dark surround). Preferred contrast levels were 0.91 to 0.99 for positive contrasts and -0.96 to -0.99 for negative contrasts. For colour/non-coloured contrasts, 90% of the partially sighted preferred yellow as the foreground colour with a contrast level above 0.89. For colour/colour contrasts, optimal assessments of 90% of all partially sighted were yellow/purple and yellow/blue with contrast levels above 0.90. The determined results are applicable for the exact experimental contrast settings only. A field manual was prepared for planning and design of contrasts suited for the partially sighted in public areas.Partially sighted, in subjective contrasts assessment, prefer bright characters of signs on a dark background for both non-coloured and colour contrasts with contrast levels above 0.9. Yellow was the preferred infield colour.

The importance of the neurobiological basis of developmental language disorders includes somatosensory modalities. Twenty-five children were diagnosed as having specific language-impairment at preschool age. All were examined with regard to their manual haptic form discrimination without visual control at a mean age of 8.7 years +/- 7.1 months. This study group was compared to age- and gender-matched normal children of equal non-verbal intelligence (control group). Haptic discrimination was measured with the Seguin formboard on which the children were required to place ten geometrical forms in appropriate holes. Both groups differed significantly in their mean quantitative performances in favor of the control group (P0.05). The difference in their mean performance and their mean discrimination times did not reach statistical significance. All results were not age-dependent. The control group on average performed significantly better with their left hands than the study group (P0.05). Qualitative analysis revealed a significant difference in haptic discrimination of the pointed forms and was probably caused by inadequate exploration procedures and/or cognitive representation deficits. The results of the children with previous developmental language disorders were interpreted as an expression of an impaired cerebral maturation.

Pictures often do not appear distorted even when viewed at oblique angles. Three hypotheses have been put forth to explain this robustness of virtual space toward affine transformations. First, array specificity holds that the perception of depicted space is fully specified by the information available at the point of observation. Second, the notion of a compensatory mechanism involves an unconscious recreation of the scene according to the original viewpoint. Third, the indiscrimination hypothesis denies the ability of the visual system to resolve or detect affine transformations up to a certain degree. Three experiments were conducted to investigate these claims. Using a double projection technique devised by Cutting (1987), Experiment I showed that observers are able to discriminate and compensate, to some degree, for affine transformations if information about the projection surface is available. However, observers relied on relative image velocities rather than reconstructing the object. In Experiment 2 additional observer motion was simulated. In single and double projection trials that required more difficult judgments of object rotation, compensation was poor and observers seemed to rely on local cues. Finally, real and simulated rotation of the projection surface revealed that observers are able to compensate for only one primary projection surface slant. The results reject the indiscrimination hypothesis and support the notion of array specificity.

The predictions provided by the range-frequency model and the adaptation-level theory were compared in respect of size judgments in an averbal two-category experiment. Squares of different sizes were presented in two different frequency distributions. After a two stimulus-two choice training, in which the subjects (N = 64) learned to which of the two response categories a relative small or large square belonged, a generalization context-series test followed. The two test series represented the two different frequency distributions used (the arithmetic mean was either smaller or larger than the median or midpoint). The percentage of large responses was registered. Furthermore, to investigate which experimental design would be appropriate for this research paradigm, the study was carried out using both a between-subjects and a within-subjects design. For the two experimental designs, the results pointed to a confirmation of the predictions provided by the adaptation-level theory (D. R. Thomas, 1993) but not the range-frequency model (Parducci, 1983, 1995).

To quantify the effects of sleep periods that have different lengths of time during continuous operations (CONOPS) 2 independent groups of subjects performed several cognitive tasks for 3 days. The 72 h trial period contained three 60-min sleep periods for the 10 subjects of the experimental group and three sleep periods of 4 h each for the 14 subjects of the control group. With the exception of only one subtest the statistical analyses of the test results of the 2 groups show no significant differences in cognitive performance. It is suggested that high motivation is responsible for comparable performance of the subjects, which was essentially obtained by a monetary pay system for successful test performance.

The DIN color chart was developed in the 1950s by Manfred Richter using of classical psychophysical scaling techniques. It is based upon the idea that colors are ordered along three subjective dimensions, i.e. hue, saturation, and brightness. Furthermore, it is assumed that the colors of the DIN color chart fulfill the principle of specific equidistancy. The main aim of this study was to investigate this claim empirically. More specifically, it was tested whether colors of the same hue and brightness are equally spaced along the dimension of subjective saturation. The data were collected in three paired comparisons experiments and were analyzed using multidimensional scaling. According to the results, the psychological properties of the DIN color system can be replicated approximately. In addition to a confirmation of the postulate of equidistancy this research contributes to the understanding of the convergence of different scaling methods.

Two studies tested whether preverbal children distinguish global categories (animal and furniture) on a conceptual basis. A total of 59 eleven-month-olds solved an object examination task. During habituation, infants freely explored different natural-looking toy models from the same category. In Study 1, the same series of four different examplars was presented twice. In Study 2, ten different exemplares were presented. In both cases, a significant habituation effect could be observed. When a perceptually new object of the same category was presented on the first test trial after habituation, a significant increase in examination time from the last habituation trial to the first test trial could be observed in Study 1. When a new object of the contrasting category was presented on the second test trial, examination times increased significantly from the first to the second test trial in both studies. These results support earlier findings suggesting that preverbal infants are able to distinguish global categories on a conceptual basis.

The abilities to segment coherent surfaces out of a discrepant background (texture segmentation) and to localize single objects out of a complex scene (visual search) are believed to occur at a peripheral level in the cortical visual pathway.Are texture segmentation and visual search innate or acquired? Can these abilities be improved in adulthood by learning? Does a disturbed early visual experience (strabismus, amblyopia) lead to a reduction of these abilities?Texture segmentation and visual search undergo a protracted development which continues well into adulthood. Even in adult observers, these abilities can be improved with practice. Learning is enduring, but not specific: It can be transferred from one task to another and between the two eyes of a given subject (including the two eyes of stereoblind subjects).We conclude that learning of texture segmentation and visual search does not involve the specific features of a visual scene, but rather reflects an improved strategy of localizing visual objects in a cluttered environment. This type of learning probably occurs at a very high level of cortical processing.

In the current study the modality-shift paradigm was applied to examine attention deficits in sleep-apnea patients. The reaction times of ipsi- and crossmodal light and sound stimuli were measured on 34 patients presenting symptoms of sleep-apnea. Some of the simple reaction times of ipsimodal (light-light; sound-sound) and crossmodal (light-sound; sound-light) stimuli correlated with mean or with minimal oxygen saturation, but did not correlate with the frequency or duration of obstructive apneas and hypopneas. However, results are different if the amount of modality-shift effect is taken into consideration. Significant correlations were found for the maximal duration of obstructive apneas and hypopneas as well as for mean oxygen saturation.

The contrast sensitivity of 41 patients with low visual acuity, as a result of age-related maculopathy, diabetic retinopathy or open-angle glaucoma, in most of them, was studied by means of the VISTECH test and the Buser LCS-test. The VISTECH test revealed reduced contrast sensitivity, especially at high frequencies. This reduction was marked in patients with diabetic retinopathy. Contrast on the color TV monitor was adjusted by the subjects. Yellow and green monitors were chosen equally often by the patients. A positive contrast (black text with light background) was preferred. The contrast required was noticeably higher than that required by subjects with normal eyes.

Two policemen who had been following and observing two young men for several hours appeared as witnesses in a criminal court case. They claimed that they had observed the young men from a distance of 375 meters putting concrete slabs onto a railway track. In order to determine whether person identification is possible at a distance of 375 meters, a field experiment was carried out. The results show that person identification at a distance of 375 meters is almost impossible. Any spontaneous identification with the naked eye is based on expectations. When using a pair of binoculars, identification is possible, but the rate of false alarms is higher than 60 percent. The results are discussed with reference to theories of perceptual and social psychology.

The recognizability of a letter is impaired by the presence of additional letters. This phenomenon is called lateral masking. Proceeding on the assumption of Bouma (1970) lateral masking can be described in terms of retinal eccentricity of the target letter and the distance between target and flanking stimuli. In this paper, we will address to the question if these kinds of parameters are adequate for describing lateral masking effects. For this purpose, characteristics of the string like its length and its homogenity are varied. The subject's task is to identify the central letter of a tachistoscopically presented string. The targets in the string are flanked both by only x and by different randomly selected letters. Additionally, we varied the length of the string. The data show that these variations influence the strength of the masking effect. It is concluded that a pure sensorical approach is not sufficient for an explanation of lateral masking effects.

Empirical investigations of perceived binocular distance often use an experimental setting in which real point-like light sources are presented in a completely dark surround. The results obtained, however, may be a consequence of the joint influence of binocular and monocular depth cues. Here, for the first time, the effect of (monocular) illumination cues on the locus of perceived equidistance is experimentally investigated by manipulating the luminous intensity of the stimuli. In a computer-controlled setup, small light-emitting diodes were presented in complete darkness. Five subjects judged the perceived distance of stimuli, which appeared in four directions and at five levels of luminous intensity, with respect to a fixed standard. Adaptive methods were used to determine perceived equidistance. Although the results show a significant effect of illumination cues, their influence on the locus of perceived equidistance turned out to be far less than previously supposed. For three subjects it was practically negligible.

Empirical and theoretical evidence for the concept of working memory is considered. We argue that the major weakness of this concept is its loose connection with the knowledge about background perceptive and cognitive processes. Results of two relevant experiments are provided. The first study demonstrated the classical chunking effect in a speeded visual search and comparison task, the proper domain of a large-capacity very short term sensory store. Our second study was a kind of extended levels-of-processing experiment. We attempted to manipulate visual, phonological, and (different) executive components of long-term memory in the hope of finding some systematic relationships between these forms of processing. Indeed, the results demonstrated a high degree of systematicity without any apparent need for a concept such as working memory for the explanation. Accordingly, the place for working memory is at all the interfaces where our metacognitive strategies interfere with mostly domain-specific cognitive mechanisms. Working memory is simply our work with memory.

Starting with a discussion on the coordination problem from different points of view within cognition the question is raised whether there is a dissociation of coordination demand of a task and the mental load for executing mental procedures. Three investigations are carried out with the paradigm of sequential mental transformations of patterns. Results of the first experiment show that coordination really requires additional mental effort beside the time necessary for mental transformation. In a further study the transfer of a coordination mechanism is proved. The influence of segmented information presentation demonstrates that amount of coordination is related to the stability and clarity of mental representations. Plans for further experiments are presented. The results are related to the current literature on working memory research.

Two experiments explored whether picture puzzles are an adequate instrument to investigate implicit memory for pictorial information. During the testing phase, the subjects had to identify hidden figures in picture puzzles. In a preceding learning phase, the priming conditions were varied systematically. In the first experiment, some subjects had to solve picture puzzles in the learning phase, whereas others made esthetic judgments (global processing) or estimated the number of triangles in the picture puzzles (local processing). In the second experiment, the subjects inspected copies of figures that were hidden at testing, modified versions of these figures, or their names in the learning phase. In the first experiment, the subjects of the different encoding conditions showed comparable priming effects. Picture puzzles that had already been processed or seen during learning were solved more often than new ones. Interview data revealed that subjects in the local or global processing conditions did not identify hidden figures at encoding. Furthermore, these subjects could not discriminate between old and new picture puzzles in a final explicit test of recognition. Thus, nonconscious storage of perceptual information that is not semantically interpreted may be sufficient to evoke priming effects. In the second experiment, the subjects in the different encoding conditions showed reliable priming effects, too. The presentation of the duplicates at encoding produced the greatest amount of priming. Effects of verbal priming, however, indicate that the solution of picture puzzles is not based solely on perceptual information. Depending on the priming conditions at learning, the solution of picture puzzles may be based primarily on data-driven processing or may be guided more heavily by conceptual information. It is concluded that perceptual, lexical, and/or conceptual information can contribute to the solution of picture puzzles.

Event-related brain potentials were recorded from a group of developmental dyslexics using a simple visual discrimination task and compared to the results of a control group. A large P3 component was elicited which did not differ in overall amplitude between groups. While the distribution was virtually symmetrical in the dyslexic group, there was a left hemispheric preponderance in the control group. The latencies of the P3 were longer in the dyslexic group than in the control group. The results are compared to findings of neuroanatomical and neuroimaging studies which revealed less hemispheric asymmetries in dyslexics compared to control subjects.

The olfactory performances of 10 visually-impaired and 9 hearing-impaired subjects were investigated by a psychophysical sniffing test (the Munich Olfaction Test). These subjects were compared with 21 control volunteers who completed the test with covered eyes, 20 control volunteers whose ears were plugged during the test and with 22 unimpaired controls. The test examined discrimination performances, detection and perception thresholds, identification abilities, olfactory memory, and hedonistic evaluations of all subjects. The present results showed that attention focusing on olfactory tasks by lowering of auditory or visual inputs did not enhance the olfactory performances of the control subjects. Also, the visually-impaired subjects did not perform better then the control subjects. The diminished olfactory abilities of the hearing-impaired were discussed against the background of delayed language acquisition.

The experiment reported here was an attempt to demonstrate that the solution of specific discrimination problems is based on rules rather than on differences in associative strengths. With positive and negative patterning as examples, we examined whether or not the solution of the discrimination problem depends on the number of reinforcements for each individual stimulus when the total number of reinforcements is kept constant. This was achieved by manipulating the number of stimuli used. We also examined the transfer to new stimuli. Forty subjects took part in a 2 x 2-factorial experiment with anticipatory skin conductance responses as the dependent variable. All the results were in accordance with the assumption of rule based problem solution. The amount of discrimination was independent of the number of reinforcements for each stimulus. Furthermore, according to results of concept formation studies, an asymmetry in transferring the solution to new stimuli was observed.

Oppel (1860/1861) first described the phenomenon that an equidistantly divided line usually looks longer than an undivided line of equal length (Oppel-Kundt illusion, OKI). The present paper begins with a discussion of the Hering-Kundt hypothesis (HKH) of the OKI. The HKH comprises two assumptions: (1) An assumption concerning the perceptual integration of the length of a single part of the divided line and the number of such parts; (2) an assumption about the psychophysical function of line length. There is no doubt that the HKH is empirically not tenable. However, nothing is known about the validity of the perceptual integration assumption when considered in isolation. It is shown that the HKH can be conceived as a special case of a more general information-integration model. According to this model, the subjective total length of a divided line is equal to the subjective length of one part of the line multiplied by the subjective number of parts. Two experiments with a total of 15 subjects are reported. The model is shown to be valid without any exception. On the background of these results published data on the OKI are re-analyzed, looking at whether they contain information about the psychophysical function for line length. It is shown that certain qualitative aspects of these data are inconsistent with a power function hypothesis while, at the same time, being compatible with a logarithmic (Fechner-) function.

Spatial ability is one of the primary mental abilities which has been subject of many empirical studies--especially in the factor analytical research. Analysing the mental processes when solving space tasks, e. g. by means of retrospective verbal reports, two different strategies can be distinguished. The first strategy (called "holistical" strategy) can be described as a mental rotation of the given stimulus, the second one (called "analytical" strategy) is characterised by nontransformal mental processes, e. g. pattern matching processes. In order to identify those different strategies, test items are required, which have different solution probabilities when being solved with different strategies. The "cube tasks" of the IST and IST-70 by Amthauer (1953, 1970) are of this type, as Putz-Osterloh (1977) has found in an experiment. The hypothesis of individual differences in solving space tasks was tested in two different samples. First the "cube tasks" of the IST-70 were administrated to 264 applicants for the pilot job. Data analyses using the mixed-Rasch-model (Rost, 1990) confirmed the hypothesis of an "analytical" and "holistical" strategy. In the second study 2558 pupils of the 7th grade were tested with the "cube tasks" of the IST. A latent class analysis of their response patterns revealed basically the "holistical" and "analytical" strategy and, in addition, four strategies which can be explained by motivational factors.

The effects of mood on thinking and behavior are characterized by "loosening" in the case of positive feeling states and "tightening" for negative ones (Fiedler, 1988). Style of cognitive processing, effort expenditure, and capacity models are discussed as explanatory concepts. To compare these approaches, the theory of signal detection provides methods for the independent evaluation of parameters of response bias and discrimination (and also efficiency). A laboratory experiment (Klauer et al., 1991) was replicated and supplemented by a field study. In the sense of convergent and discriminant validation of the insufficient techniques of mood induction, the naturally occurring mood changes of everyday life were used as mood manipulations. 13 subjects (M = 25.9 years of age, SD = 3.8) reported their feeling states on 18 days for self-selected episodes, which represented the range of their mood changes. Immediately after each mood report, they worked on a visual discrimination task. The indices of signal detection theory for response bias, discrimination, and efficiency were calculated in each cases, and correlated with measures of emotional and unspecific feeling states. Along with a shift from negative to positive feeling states, a trend towards a liberal response bias, a higher discrimination rate, and a greater efficiency resulted. Our findings replicate the laboratory experiment and support the effort expenditure and cognitive processing style view, rather than the reduced-capacity explanation. Speculations are offered concerning the emotional and cognitive processes which led to these results.

Using a series of three experiments, a cross-validation study on the dimensions of similarity of faces was carried out. In experiment 1,100 subjects sorted two sets of facial photographs (61 men, 62 women; age range 20-60) into groups of faces similar in appearance. In experiment 2, a group of 864 subjects rated a subset of 36 male and 36 female faces on a personality differential consisting of 90 scales and a physiognomic differential consisting of 29 scales. Each judge rated a single photograph on all scales. In experiment 3, the complementary subsets of 25 male and 26 female faces were rated by a third group of 48 subjects. Each judge rated one set of photographs on eight different scales from the personality sphere. Nonmetric multidimensional scaling (ALSCAL) was carried out on the similarity judgements obtained in experiment 1. Using multiple regression procedures, the ratings from experiment 2 were regressed on the coordinates of the similarity spaces. About two-thirds of the personality scales and nearly half of the physiognomic scales could be fitted into the three-dimensional similarity space. By using factor values in place of scale values, the Big Five personality factors as well as physical attractiveness and age could be fitted into the three-dimensional space. The regression coefficients obtained in experiment 2 were used to predict the scale values of the complementary subsets of stimulus persons in experiment 3. With the exception of one scale ("unlogical--logical"), the cross-validation was extraordinarily successful.

The present experiments explore the components (motor and/or sensory) underlying performance in implicit and explicit tests of memory for haptic information. In the first experiment, the encoding tasks and the test conditions were varied. During the encoding phase half of the subjects were blindfolded and explored real objects with their hands in order to answer questions about object properties (like form) as fast as possible (active exploration). The other subjects performed adequate hand movements without any sensory contact with the objects (motor encoding). At testing, for some subjects the active exploration task was repeated with old and with new objects. Other subjects who did not perform any hand movements based their judgments on sensory impressions only (passive touch). The results demonstrate reliable effects of implicit memory for haptic information, as revealed by faster reaction times to old than to new objects. However, priming effects were only obtained in the active touching test condition. This result was observed for both encoding tasks, that is, even for subjects who had only performed symbolic hand movements at encoding. Thus, the repetition of specific motor processes seems to underly the effects of repetition priming in active touch. In the second experiment, a passive touch paradigm was realized both at encoding and at test (sensory encoding). The priming effects observed under these conditions indicate that sensory processes can be relevant, too. Recognition performance was found to be influenced by other variables than measures of implicit memory. The results are discussed with respect to process-oriented and system approaches to implicit memory.

The same stimuli receive higher ratings when the distribution in which they appear is positively skewed than when it is negatively skewed (frequency effect). The effect depends on the number of stimuli (stimulus effect) and the number of categories (category effect). The effect may be caused by one of the following tendencies: (a) the tendency to assign the same number of stimuli to each category (frequency model; Parducci, 1965; ParducciPerrett, 1972); (b) the tendency to exaggerate the difference between the preceding stimulus and the present one (contrast model; Haubensak, 1984); and (c) the tendency to assign the same categories to the same stimuli (consistency model; Haubensak 1989, 1992a, 1992b, 1993). The three models are briefly described and evaluated in the light of old and new data. The consistency model seems superior to its competitors in several respects.

Jenkins and Sainsbury (1969, 1979) first described an asymmetry in pigeon's operant discrimination learning which they called a feature-positive effect. Subsequent studies demonstrated that other animals as well as humans also show a similar asymmetry. The effect is often explained as being caused by a bias in information processing which results from the neglect of negative information as a discriminative cue. The effect has also been observed in classical conditioning experiments, but not yet with human subjects. Sometimes, however, a reversal of the asymmetry, i.e., a feature-negative effect, has been observed. The experiment reported here primarily intended to demonstrate a feature-positive effect in a classical conditioning procedure with human subjects. Secondly, we also wanted to test an alternative explanation of the feature-positive effect. We found that a substantial feature-positive effect does indeed occur during classical conditioning in human subjects. Our results, however, did not fully support the alternative explanation based on rule learning.

The present study compares the ability of humans with the ability of neural networks to determine similarities between several graphic patterns. The simulated neural network was designed as a novelty filter. The stimulus material consisted of 8 different polarity profiles which were judged for their similarity under different conditions: (1) simultaneous presentation and (2) serial presentation. The judgments were collected by using the method of paired comparisons. The profile patterns were fed into the neural network to calculate novelty (similarity) values. As a further criterion for the correspondence of the profiles, a correlation coefficient (Q-coefficient) was taken. The comparison of the resulting similarity matrices shows that the performance of the novelty filter is in a good competition with the performance of a human observer. Furthermore, in both conditions the correspondence between the similarity-judgments of the subjects and the novelty values was higher than the correspondence between the judgments and the Q-coefficient. Despite this advantage the standardization of the novelty values raises some methodological problems.

It is discussed what is underlying the assumption of modality-specific processing systems and representations. Starting from the information processing approach relevant aspects of mental representations and their physiological realizations are discussed. Then three different forms of modality-specific systems are distinguished: as stimulus specific processing, as specific informational formats, and as modular part systems. Parallel to that three kinds of analogue systems are differentiated: as holding an analogue-relation, as having a specific informational format and as a set of specific processing constraints. These different aspects of the assumption of modality-specific systems are demonstrated in the example of visual and spatial information processing. It is concluded that postulating information-specific systems is not a superfluous assumption, but it is necessary, and even more likely it is an inevitable consequence of an optimization of stimulus processing.

Eight patients with phenylketonuria and low protein nutrition were treated in a double blind crossover study for the time of 3 month with 150 mg tyrosine per kg body weight and day and placebo thereafter or vice versa. The concentration of phenylalanine in serum was not influenced by the administration of tyrosine whereas tyrosine in serum markedly increased. Psychological tests were 7 times repeated in monthly intervals. From the study it is to suggest that there is an improvement of the test results caused by an effect of training due to the repeated tests and an additional improvement caused by tyrosine.

We used two different procedures for the evaluation of spatial localization errors in strabismic and anisometropic amblyopes, strabismic alternators and normal control subjects: partitioning of horizontal lines and vertical alignment. We found defective spatial localization in the amblyopic eyes of squinters with both procedures. However, in the horizontal partitioning experiment, the control subjects also showed asymmetries between the two hemifields. Thus, there is no good baseline under these conditions for the results of the amblyopic eyes of squinters. Our results show that vertical alignment is the more appropriate procedure to quantify defective spatial localization in strabismic amblyopes.

Several methods for demonstrating sequential effects in psychophysical judgments are discussed. None of them is free of problems. Simple simulations show that pseudosequential effects occur whenever some subjects judge the stimuli higher or lower than they should. Such effects may also be produced by response drifts during the course of an experiment. Breaks in the psychophysical function might be another source of pseudosequential effects. Contrary to a wide-spread opinion, it still remains to be shown that genuine sequence effects really exist.

30 subjects participated in a discrimination experiment learning face-letter associations under four rotation conditions (45 degrees, 90 degrees, 135 degrees, 180 degrees). Under each condition two thirds of the faces were presented twice, upright and rotated away from the vertical; the remaining faces were presented once, upright or rotated. Learning is described by a joint Markov model: For faces that are presented twice it assumes a separate association and encoding process (two-stage-model), for faces that are presented once it assumes an association process (all-or-none-model). The Markov model fits the data for all four rotation conditions. The angle of rotation does not affect learning for faces that are presented once. For faces that are presented twice it influences both the association and the encoding process. For the angles employed, the effect of rotation can be approximated linearly. The results suggest that the encoding of a rotated face differs increasingly from an upright face as a function of these angles of rotation. This confirms analogous conclusions from mental rotation experiments.