Hans Strasburger

Ludwig-Maximilians-University of Munich | LMU · Institute of Medical Psychology (IMP)

The retino-cortical visual pathway is retinotopically organized: Neighbourhood relationships on the retina are preserved in the mapping. Size relationships in that mapping are also highly regular: The size of a patch in the visual field that maps onto a cortical patch of fixed size follows, along any radius and over a wide range, simply a linear fu...

Non-visual photoreceptors (ipRGCs) and rods both exert a strong influence on the human pupil, yet pupil models regularly use cone-derived sensitivity as their basis. This inconsistency is further exacerbated by the fact that circadian effects can modulate the wavelength sensitivity. We assessed the pupillary reaction to narrowband light stimuli in...

Significance: This study summarizes the empirical evidence on the use of peripheral vision for the most-researched peripheral vision tools in sports. Objectives: The objective of this review was to explain if and how the tools can be used to investigate peripheral vision usage and how empirical findings with these vision tools might be transferr...

Non-visual photoreceptors (ipRGCs) and rods both exert a strong influence on the human pupil, yet pupil models regularly use cone-derived sensitivity as their basis. This inconsistency is further exacerbated by the fact that circadian effects can modulate the wavelength sensitivity. We assessed the pupillary reaction to monochromatic light stimuli...

Pure alexia and prosopagnosia traditionally have been seen as prime examples of dissociated, category-specific agnosias affecting reading and face recognition, respectively. More recent accounts have moved towards domain-independent explanations that postulate potential cross-links between different types of visual agnosia. According to one proposa...

Melanopic stimuli trigger diverse non-image-forming effects. However, evidence of a melanopic contribution to acute effects on alertness and performance is inconclusive, especially under common lighting situations. Effects on cognitive performance are likely mediated by effort-related physiological changes. We assessed the acute effects of lighting...

Purpose A variety of visual and psychometric tests have been developed for assessing on-road driving performance and fitness to drive. The diagnostic power of a state of the art psychometric test battery (Vienna Test System) combined with a set of standard visual parameters recommended for assessing fitness to drive is investigated using an on-road...

Crowding has become a hot topic in vision research, and some fundamentals are now widely agreed upon. For the classical crowding task, one would likely agree with the following statements. (1) Bouma’s law can be stated, succinctly and unequivocally, as saying that critical distance for crowding is about half the target’s eccentricity. (2) Crowding...

Crowding has become a hot topic in vision research and some fundamentals are now widely agreed upon. For the classical crowding task, one would likely agree with the following statements. (1) Bouma’s law can, succinctly and unequivocally, be stated as saying that critical distance for crowding is about half the target’s eccentricity. (2) Crowding i...

The retino-cortical visual pathway is retinotopically organized: Neighborhood relationships on the retina are preserved in the mapping to the cortex. Size relationships in that mapping are also highly regular: The size of a patch in the visual field that maps onto a cortical patch of fixed size, follows, along any radius and in a wide range, simply...

Crowding has become a hot topic in vision research and some fundamentals are now widely agreed upon. For the classical crowding task one would likely agree with the following statements. (1) Bouma’s law can be succinctly stated as saying that critical distance for crowding is about half the target’s eccentricity. (2) Crowding is predominantly a per...

Crowding has become a hot topic in vision research and some fundamentals are now widely agreed upon. For the classical crowding task one would likely agree with the following statements. (1) Bouma’s law can be sensibly stated as saying that ‘critical distance for crowding is about half the target’s eccentricity’. (2) Crowding is predominantly a per...

Crowding has become a hot topic in vision research and some fundamentals are now widely agreed upon. For the classical crowding task one would likely agree with the following statements. (1) Bouma’s law can be sensibly stated as saying that ‘critical distance for crowding is about half the target’s eccentricity’. (2) Crowding is predominantly a per...

Crowding research has become a hotbed of vision research and some fundamentals are now widely agreed upon. You would agree with the following statements – wouldn’t you? 1) Bouma’s Law can be sensibly stated as saying that ‘critical distance for crowding is about half the target’s eccentricity’. 2) Crowding is a peripheral phenomenon. 3) Crowding in...

Crowding research has become a hotbed of vision research and some fundamentals are now widely agreed upon. You would agree with the following statements – wouldn’t you? 1) Bouma’s Law can be sensibly stated as saying that ‘critical distance for crowding is about half the target’s eccentricity’. 2) Crowding is a peripheral phenomenon. 3) Crowding in...

The ability to perceive changes in motion, such as rapid changes of speed, has important ecological significance. We show that exogenous and endogenous attention have different effects on speed-change perception and operate differently in different regions of the visual field. Using a spatial-cueing paradigm, with either exogenous or endogenous cue...

Percent correct for each subject under deceleration condition in Exp 1. (XLSX)

Percent correct for each subject under acceleration condition in Exp 2. (XLSX)

Thresholds for each subject in Exp 2. (XLSX)

Thresholds for each subject in Exp 1. (XLSX)

Percent correct for each subject under acceleration condition in Exp 1. (XLSX)

Percent correct for each subject under deceleration condition in Exp 2. (XLSX)

In the following we translate accounts of some background experiments by Volkmann that were cited by Hering (1899). Our centre of interest is the result of Experiment 79 on p. 130, picked (somewhat arbitrarily and perhaps following Wundt, 1874) by Hering as an example for the just noticeable difference of distances in Volkmann’s line‐separation exp...

Towards the end of the 19th Century, Hering and Helmholtz were arguing about the fineness of visual acuity. In a talk given in 1899, Hering finally established beyond reasonable doubt that humans can see spatial displacements smaller than the diameter of a foveal cone receptor, an ability we nowadays call ‘hyperacuity’ and still the topic of active...

Siemens Star ---- The Siemens star is a radial pattern used to test the resolution of optical instruments. Its luminance profile is rectangular and under optical blur (by, e.g., bad accommodation or uncorrected short-sightedness) gives rise to spurious resolution. The latter lets one see stripes towards the center of the Siemens star that are not...

Optical blur from defocus is quite frequently considered as equivalent to low-pass filtering. Yet that belief, although not entirely wrong, is inaccurate. Here, we wish to disentangle the concepts of dioptric blur, caused by myopia or mis-accommodation, from blur due to low-pass filtering when convolving with a Gaussian kernel. Perhaps surprisingly...

Does the visual field easily extend beyond 100°? Report from the collection of textbook ducks* (in German; Poster, slightly extended) (*”textbook duck” is a new term replacing ”canard”; it’s like a hoax but done unintentionally).

Leider stimmen die in Tabelle 1 angegebenen Mindestsehschärfewerte für PKW nicht. Früher wurden im Augenarztgutachten in der Tat die in Tabelle 1 angegebenen Mindestvisuswerte von 0,5 für das bessere und 0,2 für das schlechtere Auge gefordert. ...

Die Testung des Visus als Screening‐Test zum Nachweis der Fahreignung ist weltweit verbreitet. Ob USA, Australien oder Europa – der Nachweis ausreichender Sehschärfe ist das Maß aller Dinge bei der Betrachtung von Fahreignungsvoraussetzungen. Es gibt jedoch begründete Zweifel an der Aussagekraft des Visus, wenn es darum geht, abzuschätzen, wie sich...

Psychophysical sensitivity to red-green chromatic modulation decreases with visual eccentricity, compared to sensitivity to luminance modulation, even after appropriate stimulus scaling. This is likely to occur at a central, rather than a retinal, site. Blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) responses...

We present the case of a patient having dissociative identity disorder (DID) who-after 15 years of misdiagnosed cortical blindness-step-by-step regained sight during psychotherapeutic treatment. At first only a few personality states regained vision whereas others remained blind. This could be confirmed by electrophysiological measurement, in which...

The issue of how basic sensory and temporal processing are related is still unresolved. We studied temporal processing, as assessed by simple visual reaction times (RT) and double-pulse resolution (DPR), in patients with partial vision loss after visual pathway lesions and investigated whether vision restoration training (VRT), a training program d...

James Jurin wrote an extended essay on distinct and indistinct vision in 1738. In it, he distinguished between "perfect," "distinct," and "indistinct vision" as perceptual categories, and his meticulous descriptions and analyses of perceptual phenomena contained observations that are akin to crowding. Remaining with the concepts of his day, however...

When we see an object, we know where it is. Or do we? Perhaps not in indirect vision, as was observed by the gestalt psychologist Korte in 1923. Objects and object parts appear to 'dance around', and these phenomena may underlie a part of what is called the crowding effect today. From Korte's account of pattern recognition in indirect vision, I sel...

When we see an object, we know where it is. Or do we? Perhaps not in indirect vision, as was observed by the gestalt psychologist Korte in 1923. Objects and object parts appear to 'dance around', and these phenomena may underlie a part of what is called the crowding effect today. From Korte's account of pattern recognition in indirect vision, I sel...

Visual fusion is the process in which differing but compatible binocular information is transformed into a unified percept. Even though this is at the basis of binocular vision, the underlying neural processes are, as yet, poorly understood. In our study we therefore aimed to investigate neural correlates of visual fusion. To this end, we presented...

Purpose: Orthokeratology increases higher-order optical aberrations – especially in peripheral vision. Since motion perception, additional to other factors also depends on the latter it can be expected to decrease from the treatment. The aim of this study was to investigate changes of motion perception in the peripheral visual field after orthoker...

Background / Purpose: Crowding is likely not a uniform process and several distinctions for its source have been proposed (letter confusion vs. letter substitution, within-character vs. between-character crowding, feature-source vs. letter-source confusion, and more). We re-analyzed our data (1) from a three-letter contrast-threshold crowding par...

Background / Purpose: Amplitude and polarity of the multifocal visual evoked potential (mfVEP) depend on stimulus location in the visual field – seemingly due to the idiosyncratic folding of retinotopic visual cortex. We aimed at verifying that relationship by comparing mfVEP activity maps with the orientation and distance-from-electrode of visua...

Inhibition of return (IOR) as an indicator of attentional control is characterized by an eccentricity effect, that is, the more peripheral visual field shows a stronger IOR magnitude relative to the perifoveal visual field. However, it could be argued that this eccentricity effect may not be an attention effect, but due to cortical magnification. T...

The loss of positional information for whole letters is one of the most important factors contributing to impaired letter and word recognition. Here we study the quantitative characteristics of flanker confusions in a crowding paradigm and test whether transient spatial attention relieves the crowding effect by reducing flanker confusions. We exami...

Part I described the topography of visual performance over the life span. Performance decline was explained only partly by deterioration of the optical apparatus. Part II therefore examines the influence of higher visual and cognitive functions. Visual field maps for 95 healthy observers of static perimetry, double-pulse resolution (DPR), reaction...

Temporal performance parameters vary across the visual field. Their topographical distributions relative to each other and relative to basic visual performance measures and their relative change over the life span are unknown. Our goal was to characterize the topography and age-related change of temporal performance. We acquired visual field maps i...

Psychophysical sensitivity to isoluminant chromatic modulation declines at temporal frequencies beyond 4 Hz, whereas chromatically opponent cells of the afferent visual pathway (long- to middle-wavelength (L-M) cone-opponent or short-wavelength (S) cone cells) show responses at much higher temporal frequencies, indicating a central limitation in te...

We summarize the various strands of research on peripheral vision and relate them to theories of form perception. After a historical overview, we describe quantifications of the cortical magnification hypothesis, including an extension of Schwartz's cortical mapping function. The merits of this concept are considered across a wide range of psychoph...

Visual field loss after brain lesions is commonly determined using perimetric tests of light detection (perimetry). Many patients with visual field defects complain about perceptual difficulties in areas that are perimetrically normal. To look at a potential cause for such difficulties, we topographically determined temporal characteristics of visu...

The contrast threshold for the detection of patches of light depends upon stimulus size as described by Ricco's classical law of areal summation. The critical diameter within which Ricco's law holds increases with retinal eccentricity. Here we present an analogon of Ricco's law for the recognition of characters at low contrast, and describe its var...

http://www.journalofvision.org/content/5/8/162

Correlates of visual fusion were studied independent from binocular rivalry by fMRI at various eccentricities in visual cortical areas V1 to V4 and MT+. Stimuli to elicit visual fusion (BF), binocular rivalry (BR), and simultaneous fusion and rivalry (BFR) were designed by superimposing fusable and non-fusable lattices. Responses to these were acqu...

For softcopy-reading of mammograms, a room illuminance of 10 lx is recommended in standard procedures. Room illuminance affects both the maximal monitor contrast and the global luminance adaptation of the visual system. A radiologist observer has to adapt to low luminance levels, when entering the reading room. Since the observer's sensitivity to l...

Patient RP suffers a unilateral right homonymous quadrant anopia but demonstrates better than chance discrimination for stimuli presented in the blind field at temporal frequencies between 33 and 47Hz (all significant at p<.05, binomial). Examination of her reports of visual experience during blind-field discrimination suggests a more complex pictu...

Psychophysical sensitivity to isoluminant chromatic modulation declines at temporal frequencies beyond 4 Hz, whereas chromatically opponent cells of the afferent visual pathway (long-to middle-wavelength (L–M) cone-opponent or short-wavelength (S) cone cells) show responses at much higher temporal frequencies, indicating a central limitation in tem...

Tools for medical image processing are usually evaluated by observers with radiological experience and with complex tasks. For easing evaluation of filtering and enhancement tools, the observer's task can be generalized. By describing aspects of the MCS method (Mammographic Contrast Sensitivity) we illustrate issues of selecting a metric for assess...

In radiological practice the term recognition of detail is widely used. We examined how the term can be defined and interpreted, and how recognition of detail relates to radiological phantoms such as CDMAM (Contrast Detail Mammography). For tasks in visual perception a processing hierarchy can be assumed: The perception of a structure can occur at...

For quality control in mammographic softcopy reading (SCR) a number of recommendations exists. Among them is a room illuminance of 10 lx. Moreover, the use of masks on the image seems to be advantageous, due to a reduction of scattered light in the focus of view. Room illuminance affects the global luminance adaptation and the maximal monitor contr...

In mammographic softcopy reading, assessment of contrast resolution is mainly performed with phantoms, including detection tasks with a homogeneous image background. For tasks in visual perception a processing hierarchy is assumed, where detection tasks represent the base level. The results of investigations based on detection tasks might not allow...

Visual evoked potentials from localized stimuli depend on the individual folding of the primary and secondary visual cortex. To cross-validate three non-invasive imaging approaches, we were interested to predict multifocal VEP amplitude on the scalp from retinotopic fMRI and EEG data. To obtain retinotopic information we stimulated the central visu...

Visual evoked potentials from localized stimuli depend on the personal folding of the primary and secondary visual cortex. To cross-validate three non-invasive imaging approaches, we were interested to predict multifocal VEP amplitude on the scalp from retinotopic fMRI and EEG data. To obtain retinotopic information we stimulated the central visual...

To investigate the characteristics of dynamic processing in the visual field of patients with age-related maculopathy (ARM) by measuring motion sensitivity, double-pulse resolution (DPR), and critical flicker fusion. Fourteen subjects with ARM (18 eyes), 14 age-matched controls (19 eyes), and 7 young controls (8 eyes) served as subjects. Motion con...

We present a patient with dissociative identity disorder (DID) who after 15 years of diagnosed cortical blindness gradually regained sight during psychotherapeutic treatment. At first only a few personality states regained vision, whereas others remained blind. This was confirmed by electrophysiological measurement, in which visual evoked potential...

We present a patient with dissociative identity disorder (DID) who after 15 years of diagnosed cortical blindness gradually regained sight during psychotherapeutic treatment. At first only a few personality states regained vision, whereas others remained blind. This was confirmed by electrophysiological measurement, in which visual evoked potential...

Sudden changes of visual stimulation attract attention. The observer's body motion generates retinal-flow field patterns containing information about his/her own speed and trajectory and relative motion of other objects. We investigated the effectiveness of relative motion as an attentional cue and compared it with conventional cueing by appearance...

More than a century ago, it was shown that there is an acuity deficit in peripheral vision that can be compensated for by increasing stimulus size (Aubert and Foerster 1857; Wertheim 1894). The corresponding size-scaling approach, or cortical magnification concept, has accounted for much of the eccentricity variation in grating contrast sensitivity...

Spatial cueing of transient attention has recently been shown to reduce temporal sensitivity. We investigated how the size of the sustained attentional focus influences double-pulse resolution (DPR) thresholds mapped across the visual field in a sample of 95 healthy subjects using a 9-fold interleaved adaptive algorithm (YAAP). Peripheral DPR thres...

We studied temporal integration by presenting sequences of orthogonal high-contrast sinusoidal gratings. In rapid alternation (38 Hz) gratings appear fused whereas at lower rates they appear segregated. To test whether afterimages are the source of the fused and segregated appearance, we probed the decay characteristics of a vertical grating's afte...

Functional magnetic resonance imaging (fMRI) is one of the most common methods for localising neuronal activity in the brain. Even though the sensitivity of fMRI is comparatively low, the optimisation of certain experimental parameters allows obtaining reliable results. In this article, approaches for optimising the experimental design, imaging par...

Die funktionelle Magnetresonanztomographie (fMRT) des Zentralnervensystems ist eine der meistgenutzten Methoden zur Lokalisierung neuronaler Aktivitt im Gehirn. Obwohl die Sensitivitt der fMRT vergleichsweise gering ist, kann durch die Auswahl geeigneter experimenteller Parameter die Empfindlichkeit dieses bildgebenden Verfahrens gesteigert und die...

We studied mechanisms underlying the crowding effect in indirect form vision by measuring recognition contrast sensitivity of a character with flankers to the left and right. Attentional and featural contributions to the effect can be separated by a new paradigm that distinguishes pattern location errors from pattern recognition errors and further...

When applied over the occipital pole, transcranial magnetic stimulation (TMS) disrupts visual perception and induces phosphenes. Both the underlying mechanisms and the brain structures involved are still unclear. The first part of the study characterizes the suppressive effect of TMS by psychophysical methods. Luminance increment thresholds for ori...