Jasna Martinovic

Jasna Martinovic
The University of Edinburgh | UoE · Department of Psychology

PhD, University of Leipzig

About

65
Publications
11,413
Reads
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700
Citations
Citations since 2016
29 Research Items
444 Citations
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
Introduction
Research interests: low-level colour vision mechanisms, colour categorisation, attention to colour, perceptual organisation Methods: psychophysics, EEG
Additional affiliations
September 2020 - present
The University of Edinburgh
Position
  • Senior Lecturer
September 2009 - August 2020
University of Aberdeen
Position
  • Senior Lecturer
April 2007 - September 2009
University of Liverpool
Position
  • PostDoc Position
Education
September 2004 - April 2007
University of Leipzig
Field of study
September 2002 - September 2003
University of Liverpool
Field of study
  • MSc, Cognitive and Affective Neuroscience
September 1995 - July 2001
University of Belgrade
Field of study
  • Psychology

Publications

Publications (65)
Article
Full-text available
Symmetry perception studies have generally used two stimulus types: figural and dot patterns. Here, we designed a novel figural stimulus—a wedge pattern—made of centrally aligned pseudorandomly positioned wedges. To study the effect of pattern figurality and colour on symmetry perception, we compared symmetry detection in multicoloured wedge patter...
Article
Visual working memory (WM) enables the use of past sensory experience in guiding behavior. Yet, laboratory tasks commonly evaluate WM in a way that separates it from its sensory bottleneck. To understand how perception interacts with visual memory, we used a delayed shape recognition task to probe how WM may differ for stimuli that bias processing...
Article
Full-text available
An important task for vision science is to build a unitary framework of low- and mid-level vision. As a step on this way, our study examined differences and commonalities between masking, crowding and grouping-three processes that occur through spatial interactions between neighbouring elements. We measured contrast thresholds as functions of inter...
Article
Full-text available
Crowding causes difficulties in judging attributes of an object surrounded by other objects. We investigated crowding for stimuli that isolated either S-cone or luminance mechanisms or combined them. By targeting different retinogeniculate mechanisms with contrast-matched stimuli, we aim to determine the earliest site at which crowding emerges. Dis...
Preprint
Full-text available
The idea of colour opponency maintains that colour vision arises through the comparison of two chromatic mechanisms, red versus green (RG) and yellow versus blue (YB). The four unique hues, red, green, blue, and yellow, are assumed to appear at the null points of these the two chromatic systems. However, whether unique hues have a distinct signatur...
Article
Full-text available
We investigated the dependence of perceived contrast on cone-opponent stimulus content and its spatial distribution. Participants matched a comparison patch to a light gray standard of fixed contrast. The first experiment determined the point of iso-salience for gratings, Gabors and Gaussians along cardinal directions in cone-opponent color space f...
Preprint
An important task for vision science is to build a unitary framework of low and mid-level vision. As a step on this way, our study examined differences and commonalities between masking, crowding and grouping – three processes that occur through spatial interactions between neighbouring elements. We measured contrast thresholds as functions of inte...
Preprint
Crowding causes difficulties in judging attributes of an object surrounded by other objects. We investigated crowding for stimuli that isolated either S-cone or luminance mechanisms or combined them. By targeting different retinogeniculate mechanisms, we aim to determine the earliest site at which crowding emerges. Discrimination was measured in an...
Preprint
Full-text available
We investigated spatio-chromatic contrast sensitivity in both younger and older color-normal observers. We tested how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was measured along three directions in colour space (achromatic, red-green, yell...
Article
We model color contrast sensitivity for Gabor patches as a function of spatial frequency, luminance and chromacity of the background, modulation direction in the color space and stimulus size. To fit the model parameters, we combine the data from five independent datasets, which let us make predictions for background luminance levels between 0.0002...
Article
We investigated spatio-chromatic contrast sensitivity in both younger and older color-normal observers. We tested how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was measured along three directions in colour space (achromatic, red-green, yell...
Article
The purpose of our study was to investigate the difference in spatio-chromatic contrast sensitivity between younger and older colour-normal observers. We were particularly interested in how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was meas...
Article
Full-text available
Contrast sensitivity functions (CSFs) characterize the sensitivity of the human visual system at different spatial frequencies. However, little is known about CSFs at luminances above 1000 cd/m ² , especially for color. Here, we measured contrast sensitivities at background luminances from 0.02 cd/m ² to 7000 cd/m ² and for three color directions (...
Article
Chromatic stimuli across a boundary of basic colour categories (BCCs; e.g. blue and green) are discriminated faster than colorimetrically equidistant colours within a given category. Russian has two BCCs for blue, sinij ‘dark blue’ and goluboj ‘light blue’. These language-specific BCCs were reported to enable native Russian speakers to discriminate...
Presentation
Whether visual information is individuated or texturized is susceptible to modulation at multiple processing levels. Commonly, low and mid-level visual processes are studied using disparate stimuli and tasks in a relatively small number of often well-trained observers. Here, we examine the dependencies in processing across multiple levels by invest...
Article
Full-text available
Contrast sensitivity functions (CSFs) characterize the sensitivity of the human visual system at different spatial scales, but little is known as to how contrast sensitivity for achromatic and chromatic stimuli changes from a mesopic to a highly photopic range reflecting outdoor illumination levels. The purpose of our study was to further character...
Article
Full-text available
Previous electroencephalographic research on attentional salience did not fully capture the complexities of low-level vision, which relies on both cone-opponent chromatic and cone-additive luminance mechanisms. We systematically varied color and luminance contrast using a visual search task for a higher contrast target to assess the degree to which...
Article
Shape-adaptation studies show that surround textures can inhibit the processing of contours. Using event-related potentials (ERP), we examined the time-course of neural processes involved in contour-shape and texture-shape processing following adaptation to contours and textures. Contours were made of Gabor strings whose orientations were either ta...
Article
Full-text available
Explicit or implicit assumptions about the source of illumination are a key determinant of perceived colours from the image of #TheDress. In addition, previous work showed that the extent of the processing of contextual cues in the image may be reduced in blue and black perceivers. This is a brief report of a questionnaire study which focused on th...
Article
Full-text available
Perception of visual symmetry is fast and efficient and relies on both early low-level and late mid- and high-level neural mechanisms. To test for potential influences of early low-level mechanisms on symmetry perception, we used isoluminant, achromatic, and combined (color + luminance) patterns in a psychophysical and an event-related-potential (E...
Article
Cortical networks that process colour and luminance signals are often studied separately, although colour appearance depends on both colour and luminance. In fact, objects in everyday life are very rarely defined by only colour or only luminance, necessitating an investigation into combined processing of these signals. We used steady-state visual e...
Article
Full-text available
The organization of visual processing into a coarse-to-fine information processing based on the spatial frequency properties of the input forms an important facet of the object recognition process. During visual object categorization tasks, microsaccades occur frequently. One potential functional role of these eye movements is to resolve high spati...
Article
Full-text available
The visual system processes objects embedded in complex scenes that vary in both luminance and colour. In such scenes, colour contributes to the segmentation of objects from backgrounds, but does it also affect perceptual organisation of object contours which are already defined by luminance signals, or are these processes unaffected by colour’s pr...
Article
Neuronal activity in the gamma-band range was long considered a marker of object representation. However, scalp-recorded EEG activity in this range is contaminated by a miniature saccade-related muscle artifact. Independent component analysis (ICA) has been proposed as a method of removal of such artifacts. Alternatively, beamforming, a source anal...
Article
Full-text available
Models of object recognition generally emphasize the importance of luminance-defined shape. However, it is still not fully understood how color signals combine with luminance signals to affect object-related form processing. This electroencephalographic study aimed to examine the contribution of chromatic contrast by assessing its effects on the ti...
Article
Full-text available
Background The visual system may process spatial frequency information in a low-to-high, coarse-to-fine sequence. In particular, low and high spatial frequency information may be processed via different pathways during object recognition, with LSF information projected rapidly to frontal areas and HSF processed later in visual ventral areas. In an...
Article
Emotionally arousing scenes readily capture visual attention, prompting amplified neural activity in sensory regions of the brain. The physical stimulus features and related information channels in the human visual system that contribute to this modulation, however, are not known. Here, we manipulated low-level physical parameters of complex scenes...
Article
Full-text available
Pavlovian to Instrumental Transfer (PIT) refers to the behavioral phenomenon of increased instrumental responding for a reinforcer when in the presence of Pavlovian conditioned stimuli that were separately paired with that reinforcer. PIT effects may play an important role in substance use disorders, but little is known about the brain mechanisms t...
Article
Full-text available
It is known that perceptual organization modulates the salience of visual symmetry. Reflectional symmetry is more quickly detected when it is a property of a single object than when it is formed by a gap between two objects. Translational symmetry shows the reverse effect, being more quickly detected when it is a gap between objects. We investigate...
Article
Full-text available
We investigated the interdependence of activity within the luminance (L + M) and opponent chromatic (L - M and S - [L + M]) postreceptoral mechanisms in mid-level and high-level vision. Mid-level processes extract contours and perform figure-background organization whereas high-level processes depend on additional semantic input, such as object kno...
Article
Full-text available
Until recently induced gamma-band activity (GBA) was considered a neural marker of cortical object representation. However, induced GBA in the electroencephalogram (EEG) is susceptible to artifacts caused by miniature fixational saccades. Recent studies have demonstrated that fixational saccades also reflect high-level representational processes. D...
Article
Full-text available
Three experiments were performed to assess the effect backgrounds have on object discrimination. Experiment 1 investigated the discrimination of foveally presented Gaborised objects and non-objects with and without a surrounding background. Thresholds were obtained by modulating the Gabor patches in 7 different directions, either isolating the L-M,...
Article
Full-text available
Visual object processing may follow a coarse-to-fine sequence imposed by fast processing of low spatial frequencies (LSF) and slow processing of high spatial frequencies (HSF). Objects can be categorized at varying levels of specificity: the superordinate (e.g. animal), the basic (e.g. dog), or the subordinate (e.g. Border Collie). We tested whethe...
Article
Complex organisms rely on experience to optimize the function of perceptual and motor systems in situations relevant to survival. It is well established that visual cues reliably paired with danger are processed more efficiently than neutral cues, and that such facilitated sensory processing extends to low levels of the visual system. The neurophys...
Article
Full-text available
Previous studies of feature-selective attention have focused on situations in which attention is directed to one of two spatially superimposed stimuli of equal salience. While such overlapping stimuli should maximize stimulus interactions, it is still unknown how bottom-up biases favoring one or the other stimulus influence the efficiency of featur...
Article
Full-text available
Microsaccades are miniature involuntary eye movements which occur even during fixation. The rate of occurrence of microsaccades is typified by a decrease immediately after stimulus onset and a subsequent peak; many results in the EEG gamma band may be attributable to this peak, which occurs approximately 200ms to 300ms after stimulus onset in objec...
Article
Full-text available
Expectations of drug availability increase the magnitude of attentional biases for drug-related cues. However, it is unknown whether these effects are outcome specific, or whether expectation of a specific reinforcer produces a general enhancement of attentional bias for other types of rewarding cues. In the present study, 31 social drinkers comple...
Article
Full-text available
Vision identifies objects rapidly and efficiently. In contrast, object recognition by touch is much slower. Furthermore, haptics usually serially accumulates information from different parts of objects, whereas vision typically processes object information in parallel. Is haptic object identification slower simply due to sequential information acqu...
Article
We investigated the interdependence of activity within the luminance (L þ M) and opponent chromatic (L À M and S À [L þ M]) postreceptoral mechanisms in mid-level and high-level vision. Mid-level processes extract contours and perform figure-background organization whereas high-level processes depend on additional semantic input, such as object kno...
Article
Full-text available
In aperture viewing the field-of-view is restricted, such that only a small part of an image is visible, enforcing serial exploration of different regions of an object in order to successfully recognise it. Previous studies have used either active control or passive observation of the viewing aperture, but have not contrasted the two modes. Active...
Conference Paper
Until recently induced gamma-band activity (GBA) was considered a neural marker of cortical object representation. However induced GBA in the elecetroencephalogram (EEG) is susceptible to artifacts caused by miniature eye movements. Is there a cortical induced GBA that is obscured by ocular artifacts? Furthermore, if object-specific modulations of...
Conference Paper
Recent studies indicate that small fixational eye movements can be modulated by high-level factors [Ottero-Millan et al., 2008, Journal of Vision, 8 (14), 1-18; Yuval-Greenberg et al., 2008, Neuron, 58 (3), 429-441], which suggests that they might be modulated by higher cognitive processes. The following study attempted to assess the scope of hig...
Article
Full-text available
Detection and identification of objects are the most crucial goals of visual perception. We studied the role of luminance and chromatic information for object processing by comparing performance of familiar, meaningful object contours with those of novel, non-object contours. Comparisons were made between full-color and reduced-color object (or non...
Article
Until recently induced high frequency oscillatory activity (gamma-band activity; >30 Hz) was considered a neural marker of cortical object representation. However, Yuval-Greenberg et al (2008; Neuron) demonstrated that induced gamma-band activity (GBA) in the elecetroencephalogram (EEG) is susceptible to artifacts caused by miniature eye movements,...
Article
Full-text available
Global motion integration mechanisms can utilize signals defined by purely chromatic information. Is global motion integration sensitive to the polarity of such color signals? To answer this question, we employed isoluminant random dot kinematograms (RDKs) that contain a single chromatic contrast polarity or two different polarities. Single-polarit...
Article
Cortical oscillatory activity in the gamma-band range (>30Hz) is a fundamental mechanism of neural coding that arises during a range of cognitive processes in both animals and humans. Since the first report on high frequency oscillatory synchrony between V1 neurons belonging to the same orientation column (Gray and Singer, 1989, PNAS, 86, 1698-1702...
Article
Full-text available
We have previously reported that human observers can extract global motion from random dot kinematograms (RDKs) for S-cone-isolating modulations only if the individual blobs are large (about 1 deg) and the displacement of each blob is more than about 1 deg [1,2] . We have further investigated the role of the S cones for global motion and tested whe...
Article
Full-text available
The purpose of this study was to test whether color-motion correlations carried by a pure color difference (S-cone component only) can be used to improve global motion extraction. We also examined the neural markers of color-motion correlation processing in event-related potentials. Color and motion information was dissociated using a two-colored r...
Article
Full-text available
Identification of objects can occur at different levels of specificity. Dependingon task and context, an object can be classified at the superordinate level (as ananimal), at the basic level (a bird) or at the subordinate level (a sparrow). Whatare the interactions between these representational levels and do they rely onthe same sequential process...
Article
Full-text available
Object recognition is achieved through neural mechanisms reliant on the activity of distributed neural assemblies that are thought to be coordinated by synchronous firing in the gamma-band range (>20 Hz). An outstanding question focuses on the extent to which the role of gamma oscillations in object recognition is dependent on attention. Attentiona...
Article
Object recognition is subserved by mechanisms that seem to rely on the activity of distributed neural assemblies coordinated by synchronous firing in the gamma-band range (>20 Hz). The present study relied on a novel EEG-compatible plane-rotation paradigm to elicit view-dependent processing leading to delays in the recognition of disoriented object...