Sabrina Hansmann-Roth

Sabrina Hansmann-Roth
University of Iceland | HI · Faculty of Psychology

PhD in Cognitive Science

About

49
Publications
3,214
Reads
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265
Citations

Publications

Publications (49)
Article
Full-text available
The material property of glossiness, which is attributed to many objects in our daily life, is physically independent of the objects' color. However, perceived glossiness can change with the contrast between the highlight and the area around the specular highlight. Hitherto, experiments mainly investigated gloss on unicolored surfaces. It is well k...
Article
Full-text available
Interactions between the albedo and the gloss on a surface are commonplace. Darker surfaces are perceived glossier (contrast gloss) than lighter surfaces and darker backgrounds can enhance perceived lightness of surfaces. We used maximum likelihood conjoint measurements to simultaneously quantify the strength of those effects. We quantified the ext...
Article
Full-text available
Street crossing under traffic is an everyday activity including collision detection as well as avoidance of objects in the path of motion. Such tasks demand extraction and representation of spatio-temporal information about relevant obstacles in an optimized format. Relevant task information is extracted visually by the use of gaze movements and re...
Article
Full-text available
Serial dependence in vision reflects how perceptual decisions can be biased by what we have recently perceived. Serial dependence studies test single items' effects on perceptual decisions. However, our visual world contains multiple objects at any given moment, so it's important to understand how past experiences affect not only a single object bu...
Article
It is well known that observers can use so-called summary statistics of visual ensembles to simplify perceptual processing. The assumption has been that instead of representing feature distributions in detail the visual system extracts the mean and variance of visual ensembles. But recent evidence from implicit testing using a method called feature...
Poster
Identification tasks are commonly used when assessing visual acuity (VA), constraining observers to categorical responses by only allowing them to report the item closest in appearance to an available response option. Thus, information about target appearance is lost. Here, we investigated the appearance of ten Snellen symbols, a set of high contra...
Article
Full-text available
Humans are surprisingly good at learning the statistical characteristics of their visual environment. Recent studies have revealed that not only can the visual system learn repeated features of visual search distractors, but also their actual probability distributions. Search times were determined by the frequency of distractor features over consec...
Preprint
Serial dependence in vision reflects how perceptual decisions can be biased by what we have recently perceived. Serial dependence studies test single items' effects on perceptual decisions. However, our visual world contains multiple objects at any given moment, so it's important to understand how past experiences affect not only a single object bu...
Article
Recent accounts of perception and cognition propose that the brain represents information probabilistically. While this assumption is common, empirical support for such probabilistic representations in perception has recently been criticized. Here, we evaluate these criticisms and present an account based on a recently developed psychophysical meth...
Article
Full-text available
Visual perception is, at any given moment, strongly influenced by its temporal context-what stimuli have recently been perceived and in what surroundings. We have previously shown that to-be-ignored items produce a bias upon subsequent perceptual decisions that acts in parallel with other biases induced by attended items. However, our previous inve...
Article
Full-text available
Our senses provide us with a rich experience of a detailed visual world, yet the empirical results seem to suggest severe limitations on our ability to perceive and remember. In recent attempts to reconcile the contradiction between what is experienced and what can be reported, it has been argued that the visual world is condensed to a set of summa...
Preprint
Visual perception is, at any given moment, strongly influenced by its temporal context – what stimuli have recently been perceived and in what surroundings. We have previously shown that to-be-ignored items produce a bias upon subsequent perception that acts in parallel with other biases induced by attended items. However, our previous investigatio...
Preprint
Humans are surprisingly good at learning the characteristics of their visual environment. Recent studies have revealed that not only can the visual system learn repeated features of visual search distractors, but their actual probability distributions. Search times were determined by the frequency of distractor features over consecutive search tria...
Article
Full-text available
Humans have remarkable abilities to construct a stable visual world from continuously changing input. There is increasing evidence that momentary visual input blends with previous input to preserve perceptual continuity. Most studies have shown that such influences can be traced to characteristics of the attended object at a given moment. Little is...
Preprint
Visual ensembles, like leaves on a tree, often share properties such as shape or color. Thisredundancy can be quantified as a feature probability distribution whose summary statistics (e.g.,mean) observers can report explicitly. Here, we show that such explicit reports underestimate therichness of ensemble perception. Participants (N=12 per conditi...
Preprint
Recent accounts of perception and cognition propose that the brain represents information probabilistically. While this assumption is common, empirical support for such probabilistic representations has recently been criticized. It has been argued that due to methodological limitations of perceptual experiments, probabilistic theories only provide...
Preprint
Humans have remarkable abilities to construct a stable visual world from continuously changing input. There is increasing evidence that momentary visual input blends with previous input to preserve perceptual continuity. Most studies have shown that such influences can be traced to characteristics of the attended object at a given moment. Little is...
Preprint
Humans have remarkable abilities to construct a stable visual world from continuously changing input. There is increasing evidence that momentary visual input blends with previous input to preserve perceptual continuity. Most studies have shown that such influences can be traced to characteristics of the attended object at a given moment. Little is...
Article
Full-text available
Objects have a variety of different features that can be represented as probability distributions. Recent findings show that in addition to mean and variance, the visual system can also encode the shape of feature distributions for features like color or orientation. In an odd-one-out search task we investigated observers' ability to encode two fea...
Chapter
Full-text available
We discuss how priming of attention shifts has in recent studies proved to be a useful method for studying internal representations of visual ensembles. Attentional priming is very powerful in particular when role reversals between targets and distractors occur. Such role reversals can be used to assess how expected or unexpected a particular targe...
Article
Full-text available
This study investigates systematic individual differences in the way observers perceive different kinds of surface properties and their relationship to the dress, which shows striking individual differences in colour perception. We tested whether these individual differences have a common source, namely differences in perceptual strategies accordin...
Conference Paper
Whether a surface is glossy or matte is physically independent of whether it is light or dark. Perceptually however, the albedo of specularly or diffusely reflecting surfaces can strongly influence perceived gloss (Pellacini et al., 2000, Proceedings of SIGGRAPH). Here we ask whether glossiness judgments are more constrained if there are variations...
Conference Paper
The presence of a bright, specular highlight is one of the most important factors in gloss perception. Previous work has shown that even when highlights cover only a small region on a surface, they lead to the impression that an object has a uniform surface material (Beck 1981, Percept. Psychophys.). In the present study we investigate whether perc...
Data
Full-text available
Street crossing under traffic is an everyday activity including collision detection as well as avoidance of objects in the path of motion. Such tasks demand extraction and representation of spatio-temporal information about relevant obstacles in an optimized format. Relevant task information is extracted visually by the use of gaze movements and re...

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