Ignacio Serrano-Pedraza

Ignacio Serrano-Pedraza
Complutense University of Madrid | UCM · Department of Basic Psychology I (Basic Processes)

PhD in Experimental Psychology

About

132
Publications
25,562
Reads
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2,179
Citations
Additional affiliations
February 2001 - January 2006
Complutense University of Madrid
Position
  • Professor (Associate)
December 2007 - June 2008
University of Kent
Position
  • PostDoc Position
December 2010 - present
Complutense University of Madrid
Position
  • Professor (Full)
Description
  • Visiting Researcher of the Institute of Neuroscience. Newcastle University, UK

Publications

Publications (132)
Article
Full-text available
The motion energy model is the standard account of motion detection in animals from beetles to humans. Despite this common basis, we show here that a difference in the early stages of visual processing between mammals and insects leads this model to make radically different behavioural predictions. In insects, early filtering is spatially lowpass,...
Article
Full-text available
New forms of stereoscopic 3-D technology offer vision scientists new opportunities for research, but also come with distinct problems. Here we consider autostereo displays where the two eyes' images are spatially interleaved in alternating columns of pixels and no glasses or special optics are required. Column-interleaved displays produce an excell...
Article
Full-text available
Purpose: Human vision has a puzzling stereoscopic anisotropy: horizontal depth corrugations are easier to detect than vertical depth corrugations. To date, little is known about the function or the underlying mechanism responsible for this anisotropy. Here, we aim to find out whether this anisotropy is independent of age. To answer this, we compar...
Article
Full-text available
In the study of the spatial characteristics of the visual channels, the power spectrum model of visual masking is one of the most widely used. When the task is to detect a signal masked by visual noise, this classical model assumes that the signal and the noise are previously processed by a bank of linear channels and that the power of the signal a...
Article
Full-text available
To investigate the cortical mechanisms that prevent diplopia in intermittent exotropia (X(T)) during binocular alignment (orthotropia). The authors studied 12 X(T) patients aged 5 to 22 years. Seventy-five percent had functional stereo vision with stereoacuity similar to that of 12 age-matched controls (0.2-3.7 min arc). Identical face images were...
Preprint
Full-text available
When tracking with the eyes an object moving against a textured background, the background retinal image moves in the opposite direction to the smooth pursuit eye movement. Optokinetic responses, such as optokinetic nystagmus (OKN) or ocular tracking, to this reafferent signal must be suppressed to sustain pursuit of the object-of-interest. We vari...
Preprint
The estimation of motion is a fundamental process for any sighted animal. Computational models for motion sensors have a long and successful history but they still suffer from fundamental shortcomings, as they disagree with physiological evidence and each model is dedicated to a specific type of motion, which is controversial from a biological stan...
Article
Full-text available
Masking experiments, using vertical and horizontal sinusoidal depth corrugations, have suggested the existence of more than two spatial‐frequency disparity mechanisms. This result was confirmed through an individual differences approach. Here, using factor analytic techniques, we want to investigate the existence of independent temporal mechanisms...
Article
Recent results have shown that males have lower duration thresholds for motion direction discrimination than females. Measuring contrast thresholds, a previous study has shown that males have a greater sensitivity to fine details and fast flickering stimuli than females, and that females have a higher sensitivity to low spatial frequencies modulate...
Article
Full-text available
Purpose: The stereoscopic anisotropy is one of the most intriguing phenomena of stereoscopic vision. It shows that the disparity thresholds to detect three-dimensional sinusoidal horizontal corrugations are much lower than for vertical corrugations for spatial frequencies lower than 1 cycles/deg. A recent study has shown that the anisotropy increa...
Article
Full-text available
During smooth pursuit eye movements, the visual system is faced with the task of telling apart reafferent retinal motion from motion in the world. While an efference copy signal can be used to predict the amount of reafference to subtract from the image, an image-based adaptive mechanism can ensure the continued accuracy of this computation. Indeed...
Article
Full-text available
Motion discrimination of large stimuli is impaired at high contrast and short durations. This psychophysical result has been linked with the center-surround suppression found in neurons of area MT. Recent physiology results have shown that most frontoparallel MT cells respond more strongly to binocular than to monocular stimulation. Here we measure...
Article
The characterization of vibrotactile perception is crucial to accurately configure haptic devices and create appropriate stimuli for improving user performance in human-machine interaction systems. This paper presents a study aiming to determine the absolute and differential vibrotactile thresholds in different areas of the torso to develop reliabl...
Article
The study of motion perception through classical psychophysical methods has suggested that independent spatiotemporal filters acting over specific locations in retinal images carry out early motion processing. On the other hand, individual differences approaches have been able to identify a structure of spatiotemporal filters too. In this same fash...
Article
Full-text available
Purpose: In 2019, we described ASTEROID, a new stereotest run on a 3D tablet computer which involves a four-alternative disparity detection task on a dynamic random-dot stereogram. Stereo thresholds measured with ASTEROID were well correlated with, but systematically higher than (by a factor of around 1.5), thresholds measured with previous labora...
Article
Motion direction discrimination becomes impaired when combinations of drifting high spatial frequency (HSF) and static low spatial frequency (LSF) patterns are merged into a compound stimulus. Such impairment has been suggested to occur due to an interaction between motion sensors tuned to coarse and fine scale spatial patterns. This interaction is...
Article
Full-text available
Bayesian staircases are widely used in psychophysics to estimate detection thresholds. Simulations have revealed the importance of the parameters selected for the assumed subject’s psychometric function in enabling thresholds to be estimated with small bias and high precision. One important parameter is the slope of the psychometric function, or eq...
Preprint
Bayesian staircases are widely used in psychophysics to estimate detection thresholds. Simulations have revealed the importance of the parameters selected for the assumed subject’s psychometric function in enabling thresholds to be estimated with small bias and high precision. One important parameter is the slope of the psychometric function, or eq...
Article
Full-text available
Purpose: To describe a new stereotest in the form of a game on an autostereoscopic tablet computer designed to be suitable for use in the eye clinic and present data on its reliability and the distribution of stereo thresholds in adults. Methods: Test stimuli were four dynamic random-dot stereograms, one of which contained a disparate target. Fe...
Article
Full-text available
The perceived direction of motion of a brief moving fine scale pattern reverses when a static coarse scale pattern is added to it (Henning & Derrington, 1988). This impairment in motion direction discrimination has been explained by the inhibitory interaction between motion sensors tuned to fine and coarse scales. This interaction depends on the pa...
Article
Motion discrimination of high spatial-frequency stimuli is impaired when a static low spatial-frequency component is added to it. However, motion discrimination is facilitated when a static high-frequency component is added to a low-frequency moving stimulus (Serrano-Pedraza et al., 2013 JoV). Previous studies show that this interaction between mot...
Article
Full-text available
Purpose Measuring accurate thresholds in children can be challenging. A typical psychophysical experiment is usually too long to keep children engaged. However, a reduction in the number of trials decreases the precision of the threshold estimate. We evaluated the efficiency of forced-choice paradigms with 2 or 4 alternatives (2-AFC, 4-AFC) in a di...
Article
Full-text available
The impairment to discriminate the motion direction of a large high contrast stimulus or to detect a stimulus surrounded by another one is called visual suppression and is the result of the normal function of our visual inhibitory mechanisms. Recently, Melnick et al. (2013), using a motion discrimination task, showed that intelligence strongly corr...
Data
The data presented in this paper. (XLSX)
Article
Full-text available
Recently, we showed a novel property of the Hassenstein-Reichardt detector, namely that insect motion detection can be masked by 'undetectable' noise, i.e. visual noise presented at spatial frequencies at which coherently moving gratings do not elicit a response (Tarawneh et al., 2017). That study compared the responses of human and insect motion d...
Article
Full-text available
Threshold functions for sinusoidal depth corrugations typically reach their minimum (highest sensitivity) at spatial frequencies of 0.2-0.4 cycles/degree (cpd), with lower thresholds for horizontal than vertical corrugations at low spatial frequencies. To elucidate spatial frequency and orientation tuning of stereoscopic mechanisms, we measured the...
Article
Aims: The interaction between surgical lighting and laminar airflow is poorly understood. We undertook an experiment to identify any effect contemporary surgical lights have on laminar flow and recommend practical strategies to limit any negative effects. Materials and methods: Neutrally buoyant bubbles were introduced into the surgical field of...
Article
Full-text available
The interaction between surgical lighting and laminar airflow is poorly understood. We undertook an experiment to identify any effect contemporary surgical lights have on laminar flow and recommend practical strategies to limit any negative effects. Materials and Methods Neutrally buoyant bubbles were introduced into the surgical field of a simulat...
Preprint
Full-text available
Recently, we showed a novel property of the Hassenstein-Reichardt detector: namely, that insect motion detection can be masked by “invisible” noise, i.e. visual noise presented at spatial frequencies to which the animals do not respond when presented as a signal. While this study compared the effect of noise on human and insect motion perception, i...
Article
Full-text available
Purpose: It has been repeatedly shown that the TNO stereotest overestimates stereo threshold compared to other clinical stereotests. In the current study, we test whether this overestimation can be attributed to a distinction between 'global' (or 'cyclopean') and 'local' (feature or contour-based) stereopsis. Methods: We compared stereo threshol...
Preprint
Full-text available
The motion energy model is the standard account of motion detection in animals from beetles to humans. Despite this common basis, we show here that a difference in the early stages of visual processing between mammals and insects leads this model to make radically different behavioural predictions. In insects, early filtering is spatially lowpass,...
Article
Full-text available
The optomotor response has been widely used to investigate insect sensitivity to contrast and motion. Several studies have revealed the sensitivity of this response to frequency and contrast, but we know less about the spatial integration underlying this response. Specifically, few studies have investigated how the horizontal angular extent of stim...
Article
Full-text available
Research on facial emotion processing has offered inconclusive results on whether certain emotional expressions, like happiness, are detected faster over others. A source of discrepancy among studies could stem from differences in physically salient features (e.g., teeth visibility), which are often left uncontrolled in this field of research. In S...
Article
Adaptive Bayesian procedures are widely used in psychophysics to estimate detection thresholds. Simulations have revealed the importance of the parameters selected for the model likelihood function in obtaining threshold estimates with small bias and standard error (Alcalá-Quintana & GarcNúcleoa-Perez, 2004). One recommendation is that the spread (...
Article
Introduction Measuring accurate thresholds in children can be challenging. A typical psychophysical experiment is usually too long to keep children engaged. However, a reduction in the number of trials decreases the precision of the threshold estimate. We evaluated the efficiency of forced-choice paradigms with 2 or 4 alternatives (2AFC, 4AFC) in a...
Article
Full-text available
Previous research has shown a visual asymmetry in shaded stimuli where the perceived contrast depended on the polarity of their dark and light areas (Chacón, 2004). In particular, circles filled out with a top-dark luminance ramp were perceived with higher contrast than top-light ones although both types of stimuli had the same physical contrast. H...
Article
Dislocation of the acromioclavicular joint is a relatively common injury and a number of surgical interventions have been described for its treatment. Recently, a synthetic ligament device has become available and been successfully used, however, like other non-native solutions, a compromise must be reached when choosing non-anatomical locations fo...
Article
Full-text available
Purpose: To measure the angular relationship between the Neviaser portal and the superior glenoid labrum in 60 cadaveric specimens to determine whether this portal can be used for reliable anchor placement. Methods: The Neviaser portal of 30 left and 30 right unpaired dry cadaveric scapulae with clavicles were measured by a single observer using...
Article
Full-text available
Psychophysical surround suppression is believed to reflect inhibitory neuronal mechanisms in visual cortex. In recent years, two psychophysical measures of surround suppression have been much studied: (i) duration thresholds on a motion-discrimination task (which are worse for larger than for smaller stimuli) and (ii) contrast thresholds on a contr...
Article
The detection of a grating located in the periphery is impaired by the presence of a surrounding grating of same spatial frequency and orientation. This suppression is the psychophysical counterpart of the surround suppression found in the striate cortex that is orientation tuned and can be mediated dichoptically (De Angelis, et al 1994). The propo...
Article
The existence of multiple channels selective for spatial frequency in human motion perception has been shown by masking experiments (Anderson & Burr, 1989). We examined this in humans and praying mantises. The "signal" stimuli were vertically-oriented sinusoidal luminance gratings of either Low or High spatial frequency, moving either left or right...
Poster
Nityananda et al. (2015) report spatial and temporal contrast sensitivity functions for Sphodromantis lineola. We have reanalyzed these data using techniques developed to extract the number and tuning of spatiotemporal channels using individual differences in data (Peterzell et al., 1991; 1993; 1995; 1996; 2000; Sekuler et al., 1984). For 6 insects...
Article
Full-text available
A well-studied paradox of motion perception is that, in order to correctly judge direction in high-contrast stimuli, subjects need to observe motion for longer in large stimuli than in small stimuli. This effect is one of several perceptual effects known generally as "surround suppression." It is usually attributed to center-surround antagonism bet...
Article
Full-text available
Visual perception in schizophrenia is attracting a broad interest given the deep knowledge that we have about the visual system in healthy populations. One example is the class of effects known collectively as visual surround suppression. For example, the visibility of a grating located in the visual periphery is impaired by the presence of a surro...
Book
Este manual recoge el contenido de algunas de las clases prácticas de carácter experimental impartidas en la Facultad de Psicología de la Universidad Complutense de Madrid durante los últimos veinticinco años. Las prácticas se componen de demostraciones y experimentos psicofísicos relacionados con fenómenos visuales y auditivos y han sido diseñadas...
Article
Full-text available
The effects of different masking conditions on identification of face gender and expression at different target durations (17-119 ms time range) were studied in two experiments. In Experiments 1a and 1b, the effects of face masks were compared against those of noise masks (scrambled face stimuli) and a control, no-mask condition. Significant maskin...
Article
Full-text available
Our ability to discriminate motion direction in a Gabor patch diminishes with increasing size and contrast, indicating surround suppression. Discrimination is also impaired by a static low-spatial-frequency patch added to the moving stimulus, suggesting an antagonism between sensors tuned to fine and coarse features. Using Bayesian staircases, we m...