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Sharvashidze N, Hübner C, Schütz AC. A bias in transsaccadic perception of spatial frequency changes. Vision Res 2024; 222:108453. [PMID: 38991467 DOI: 10.1016/j.visres.2024.108453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 06/23/2024] [Accepted: 06/24/2024] [Indexed: 07/13/2024]
Abstract
Visual processing differs between the foveal and peripheral visual field. These differences can lead to different appearances of objects in the periphery and the fovea, posing a challenge to perception across saccades. Differences in the appearance of visual features between the peripheral and foveal visual field may bias change discrimination across saccades. Previously it has been reported that spatial frequency (SF) appears higher in the periphery compared to the fovea (Davis et al., 1987). In this study, we investigated the visual appearance of SF before and after a saccade and the discrimination of SF changes during saccades. In addition, we tested the contributions of pre- and postsaccadic information to change discrimination performance. In the first experiment, we found no differences in the appearance of SF before and after a saccade. However, participants showed a clear bias to report SF increases. Interestingly, a 200-ms postsaccadic blank improved the precision of the responses but did not affect the bias. In the second experiment, participants showed lower thresholds for SF increases than for decreases, suggesting that the bias in the first experiment was not just a response bias. Finally, we asked participants to discriminate the SF of stimuli presented before a saccade. Thresholds in the presaccadic discrimination task were lower than in the change discrimination task, suggesting that transsaccadic change discrimination is not merely limited by presaccadic discrimination in the periphery. The change direction bias might stem from more effective masking or overwriting of the presaccadic stimulus by the postsaccadic low SF stimulus.
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Affiliation(s)
- Nino Sharvashidze
- Allgemeine und Biologische Psychologie, Philipps-Universität Marburg, Marburg, Germany.
| | - Carolin Hübner
- Allgemeine Psychologie & Human Factors, Technische Universität Chemnitz, Chemnitz, Germany
| | - Alexander C Schütz
- Allgemeine und Biologische Psychologie, Philipps-Universität Marburg, Marburg, Germany
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Wittevrongel B, Khachatryan E, Carrette E, Boon P, Meurs A, Van Roost D, Van Hulle MM. High-gamma oscillations precede visual steady-state responses: A human electrocorticography study. Hum Brain Mapp 2020; 41:5341-5355. [PMID: 32885895 PMCID: PMC7670637 DOI: 10.1002/hbm.25196] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 08/03/2020] [Accepted: 08/18/2020] [Indexed: 12/24/2022] Open
Abstract
The robust steady-state cortical activation elicited by flickering visual stimulation has been exploited by a wide range of scientific studies. As the fundamental neural response inherits the spectral properties of the gazed flickering, the paradigm has been used to chart cortical characteristics and their relation to pathologies. However, despite its widespread adoption, the underlying neural mechanisms are not well understood. Here, we show that the fundamental response is preceded by high-gamma (55-125 Hz) oscillations which are also synchronised to the gazed frequency. Using a subdural recording of the primary and associative visual cortices of one human subject, we demonstrate that the latencies of the high-gamma and fundamental components are highly correlated on a single-trial basis albeit that the latter is consistently delayed by approximately 55 ms. These results corroborate previous reports that top-down feedback projections are involved in the generation of the fundamental response, but, in addition, we show that trial-to-trial variability in fundamental latency is paralleled by a highly similar variability in high-gamma latency. Pathology- or paradigm-induced alterations in steady-state responses could thus originate either from deviating visual gamma responses or from aberrations in the neural feedback mechanism. Experiments designed to tease apart the two processes are expected to provide deeper insights into the studied paradigm.
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Affiliation(s)
| | | | - Evelien Carrette
- Laboratory of Clinical and Experimental NeurophysiologyGhent University HospitalGhentBelgium
| | - Paul Boon
- Laboratory of Clinical and Experimental NeurophysiologyGhent University HospitalGhentBelgium
| | - Alfred Meurs
- Laboratory of Clinical and Experimental NeurophysiologyGhent University HospitalGhentBelgium
| | - Dirk Van Roost
- Department of NeurosurgeryGhent University HospitalGhentBelgium
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Min SH, Reynaud A, Hess RF. Interocular Differences in Spatial Frequency Influence the Pulfrich Effect. Vision (Basel) 2020; 4:vision4010020. [PMID: 32244910 PMCID: PMC7157571 DOI: 10.3390/vision4010020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 11/16/2022] Open
Abstract
The Pulfrich effect is a stereo-motion phenomenon. When the two eyes are presented with visual targets moving in fronto-parallel motion at different luminances or contrasts, the perception is of a target moving-in-depth. It is thought that this percept of motion-in-depth occurs because lower luminance or contrast delays the speed of visual processing. Spatial properties of an image such as spatial frequency and size have also been shown to influence the speed of visual processing. In this study, we use a paradigm to measure interocular delay based on the Pulfrich effect where a structure-from-motion defined cylinder, composed of Gabor elements displayed at different interocular phases, rotates in depth. This allows us to measure any relative interocular processing delay while independently manipulating the spatial frequency and size of the micro elements (i.e., Gabor patches). We show that interocular spatial frequency differences, but not interocular size differences of image features, produce interocular processing delays.
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Jeantet C, Caharel S, Schwan R, Lighezzolo-Alnot J, Laprevote V. Factors influencing spatial frequency extraction in faces: A review. Neurosci Biobehav Rev 2018. [DOI: 10.1016/j.neubiorev.2018.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Barsingerhorn AD, Boonstra FN, Goossens J. Development of Symbol Discrimination Speed in Children With Normal Vision. Invest Ophthalmol Vis Sci 2018; 59:3973-3983. [PMID: 30073368 DOI: 10.1167/iovs.17-23168] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Many visually guided tasks require rapid perception of visual details, but how fast children can discern foveal stimuli and how this ability improves with age are still unknown. To fill this gap, we tested normally sighted children between 5 and 12 years of age with a combined symbol-discrimination reaction-time test. Methods Children (n = 94) had to indicate, as fast and accurately as possible, the orientation of a Landolt C symbol (90 trials). Task difficulty was manipulated by varying symbol size (-0.43 to 1.09 logMAR at 5 m). The resulting reaction times were analyzed with a drift-diffusion model. Reaction times on a visual and auditory detection task were measured to assess the contribution of other factors, such as delays in stimulus detection and executing the motor response. Results Detection and discrimination were significantly faster in older children. Five-year-olds needed ∼440 ms for visual detection and ∼980 ms for discrimination of the largest symbols while 12-year-olds needed only ∼250 ms and ∼500 ms for this. The extra time needed for discrimination compared with detection decreased with age. The decrease in reaction time with increasing optotype size was also age-dependent and indicated an increase in sensitivity with age. Despite the time pressure, acuity thresholds were normal (within the EN ISO-8597 standard). Conclusions Our data revealed substantial developmental improvements in visual discrimination speed, which suggests that an important optimization takes place in the developing visual system of 5- to 12-year-old children. Since the speed-acuity test allows for quick and reliable assessment of visual recognition acuity and speed, it may be useful in clinical testing too.
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Affiliation(s)
- Annemiek D Barsingerhorn
- Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre Nijmegen, Nijmegen, The Netherlands.,Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - F Nienke Boonstra
- Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre Nijmegen, Nijmegen, The Netherlands.,Royal Dutch Visio, National Foundation for the Visually Impaired and Blind, Huizen, The Netherlands.,Bartiméus, Institute for the Visually Impaired, Zeist, The Netherlands
| | - Jeroen Goossens
- Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre Nijmegen, Nijmegen, The Netherlands
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Abstract
The existence of a temporal anisotropy in the integration of spatial frequencies, such that spatial frequencies are integrated more effectively if they are available from low to high through time, has been examined in a series of experiments. In the first experiment, the first three harmonics of a square wave were presented in a low-to-high or a high-to-low sequence in a temporal two-interval forced-choice experiment. Subjects were asked to indicate which sequence appeared to resemble a square wave more. A high-to-low sequence of spatial frequencies was judged to more resemble the target than the low-to-high sequence. These results support a temporal anisotropy in the integration of spatial frequencies of exactly the opposite form to that suggested from previous results. Further experiments established that this was not due to task differences or to subjects basing their decision on the final spatial frequency shown. An interpretation is offered in which an isotropic mechanism for spatial-frequency integration is combined with a recency bias.
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7
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On the Differentiation of Foveal and Peripheral Early Visual Evoked Potentials. Brain Topogr 2016; 29:506-14. [DOI: 10.1007/s10548-016-0475-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/02/2016] [Indexed: 10/22/2022]
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Escoffier N, Herrmann CS, Schirmer A. Auditory rhythms entrain visual processes in the human brain: Evidence from evoked oscillations and event-related potentials. Neuroimage 2015; 111:267-76. [DOI: 10.1016/j.neuroimage.2015.02.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 02/09/2015] [Accepted: 02/11/2015] [Indexed: 10/24/2022] Open
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10
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The effects of uniform field flicker and blurring on the global precedence effect. ACTA ACUST UNITED AC 2013. [DOI: 10.3758/bf03333921] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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11
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Tsuruhara A, Nagata Y, Suzuki M, Inui K, Kakigi R. Effects of spatial frequency on visual evoked magnetic fields. Exp Brain Res 2013; 226:347-55. [DOI: 10.1007/s00221-013-3440-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 02/02/2013] [Indexed: 11/25/2022]
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Norcia AM, Clarke M, Tyler CW. Digital filtering and robust regression techniques for estimating sensory thresholds from the evoked potential. ACTA ACUST UNITED AC 2011; 4:26-32. [PMID: 19493780 DOI: 10.1109/memb.1985.5006224] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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13
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de Vries JP, Hooge ITC, Wiering MA, Verstraten FAJ. How Longer Saccade Latencies Lead to a Competition for Salience. Psychol Sci 2011; 22:916-23. [DOI: 10.1177/0956797611410572] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
It has been suggested that independent bottom-up and top-down processes govern saccadic selection. However, recent findings are hard to explain in such terms. We hypothesized that differences in visual-processing time can explain these findings, and we tested this using search displays containing two deviating elements, one requiring a short processing time and one requiring a long processing time. Following short saccade latencies, the deviation requiring less processing time was selected most frequently. This bias disappeared following long saccade latencies. Our results suggest that an element that attracts eye movements following short saccade latencies does so because it is the only element processed at that time. The temporal constraints of processing visual information therefore seem to be a determining factor in saccadic selection. Thus, relative saliency is a time-dependent phenomenon.
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Affiliation(s)
- Jelmer P. de Vries
- Helmholtz Institute and Department of Experimental Psychology, Neuroscience & Cognition Utrecht, Utrecht University
| | - Ignace T. C. Hooge
- Helmholtz Institute and Department of Experimental Psychology, Neuroscience & Cognition Utrecht, Utrecht University
| | - Marco A. Wiering
- Department of Artificial Intelligence, Faculty of Mathematics and Natural Sciences, University of Groningen
| | - Frans A. J. Verstraten
- Helmholtz Institute and Department of Experimental Psychology, Neuroscience & Cognition Utrecht, Utrecht University
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14
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Different regions of space or different spaces altogether: What are the dorsal/ventral systems processing? Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00080183] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Functional specialization in the lower and upper visual fields in humans: Its ecological origins and neurophysiological implications. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00080018] [Citation(s) in RCA: 420] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractFunctional specialization in the lower and upper visual fields in humans is analyzed in relation to the origins of the primate visual system. Processing differences between the vertical hemifields are related to the distinction between near (peripersonal) and far (extrapersonal) space, which are biased toward the lower and upper visual fields, respectively. Nonlinear/global processing is required in the lower visual field in order to pergeive the optically degraded and diplopic images in near vision, whereas objects in far vision are searched for and recognized primarily using linear/local perceptual mechanisms. The functional differences between near and far visual space are correlated with their disproportionate representations in the dorsal and ventral divisions of visual association cortex, respectively, and in the magnocellular and parvocellular pathways that project to them. Advances in far visual capabilities and forelimb manipulatory skills may have led to a significant enhancement of these functional specializations.
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21
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Keyser MD, Vissenberg I, Neetens A. Are visually evoked potentials (VEP) useful for determination of visual acuity?: A clinical trial. Neuroophthalmology 2009. [DOI: 10.3109/01658109008997277] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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22
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Yadav NK, Almoqbel F, Head L, Irving EL, Leat SJ. Threshold determination in sweep VEP and the effects of criterion. Doc Ophthalmol 2009; 119:109-21. [PMID: 19554357 DOI: 10.1007/s10633-009-9177-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 06/04/2009] [Indexed: 11/25/2022]
Abstract
In order to develop criteria for the range of data points used for regression line fitting in sweep visually evoked potential (sVEP), which would be objective, clearly specified and give good repeatability and validity, and in order to investigate the effect of luminance on sVEP measurement, visual acuity (VA) and contrast sensitivity (CS) were measured with sVEP in adults aged 17-30 years and children aged 6-8 years. Six to ten participants took part in each experiment. Five criteria (C0-C4) for fitting the regression line were implemented. Test-retest repeatability and validity against psychophysical thresholds at three luminance levels were considered for thresholds and the number of acceptable readings. There were significant effects of criteria (repeated measures ANOVAs, P < 0.05). The criteria, C2 and C3 (based on the range over which the signal-to-noise ratio >or=1), consistently gave better VA and CS, more viable readings, better agreement with psychophysical thresholds in adults and better repeatability than the other criteria. In the case of adults, C2 gave thresholds that were not significantly different from the psychophysical thresholds (P > 0.05). There was little effect of luminance over the 25-100 cd/m(2) range used. Overall, C2 performed the best and would be the criterion of choice, giving better repeatability, better validity and more viable plots.
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Grossberg S, Seidman D. Neural dynamics of autistic behaviors: cognitive, emotional, and timing substrates. Psychol Rev 2006; 113:483-525. [PMID: 16802879 DOI: 10.1037/0033-295x.113.3.483] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
What brain mechanisms underlie autism, and how do they give rise to autistic behavioral symptoms? This article describes a neural model, called the Imbalanced Spectrally Timed Adaptive Resonance Theory (iSTART) model, that proposes how cognitive, emotional, timing, and motor processes that involve brain regions such as the prefrontal and temporal cortex, amygdala, hippocampus, and cerebellum may interact to create and perpetuate autistic symptoms. These model processes were originally developed to explain data concerning how the brain controls normal behaviors. The iSTART model shows how autistic behavioral symptoms may arise from prescribed breakdowns in these brain processes, notably a combination of underaroused emotional depression in the amygdala and related affective brain regions, learning of hyperspecific recognition categories in the temporal and prefrontal cortices, and breakdowns of adaptively timed attentional and motor circuits in the hippocampal system and cerebellum. The model clarifies how malfunctions in a subset of these mechanisms can, through a systemwide vicious circle of environmentally mediated feedback, cause and maintain problems with them all.
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Affiliation(s)
- Stephen Grossberg
- Department of Cognitive and Neural Systems, Center for Adaptive Systems and Center of Excellence for Learning in Education, Science, and Technology, Boston University, 677 Beacon Street, Boston, MA 02215, USA.
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24
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Mitov DL, Totev TT. Temporal summation and reaction times for detecting gratings. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2005; 35:417-22. [PMID: 15929570 DOI: 10.1007/s11055-005-0042-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The effects of the duration of presentation of stimuli on the reaction time for detection of gratings of different spatial frequencies were studied. The product of contrast and duration (the contrast "energy") was kept constant for each duration. These experiments showed that at near-threshold "energies," reaction times did not change with increases in the duration to 15 and 30 msec at low and high spatial frequencies respectively. At high contrast "energies," this critical duration was identical (15 msec) for both low and high spatial frequencies. The effects of the duration of a linearly increasing front for grating presentation on detection reaction times were also studied. Increases in the duration of the front (to 60 msec) significantly lengthened the reaction time at low spatial frequencies at all contrast levels studied. Conversely, at high spatial frequencies, a significant increase in the reaction time was seen only at high contrast levels. These results suggest that reaction time depends on two types of mechanisms (phasic and tonic) at near-threshold contrast and one type (phasic) at high contrast.
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Affiliation(s)
- D L Mitov
- Institute of Physiology, Bulgarian Academy of Sciences, 23 Academician G. Bonchev Street, 1113 Sofia, Bulgaria
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25
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Ludwig CJH, Gilchrist ID, McSorley E. The influence of spatial frequency and contrast on saccade latencies. Vision Res 2004; 44:2597-604. [PMID: 15358075 DOI: 10.1016/j.visres.2004.05.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2003] [Revised: 05/14/2004] [Indexed: 11/21/2022]
Abstract
We characterised the impact of spatial frequency and contrast on saccade latencies to single Gabor patches. Saccade latencies decreased as a function of contrast, and increased with spatial frequency. The observed latency variations are qualitatively similar to those observed for manual reaction times. For single target detection, our findings highlight the similarity in the visual processes that support both saccadic and manual responses.
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Affiliation(s)
- Casimir J H Ludwig
- Department of Experimental Psychology, University of Bristol, Bristol BS8 1TN, UK.
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26
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Ellemberg D, Lavoie K, Lewis TL, Maurer D, Lepore F, Guillemot JP. Longer VEP latencies and slower reaction times to the onset of second-order motion than to the onset of first-order motion. Vision Res 2003; 43:651-8. [PMID: 12604101 DOI: 10.1016/s0042-6989(03)00006-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We compared visual evoked potentials and psychophysical reaction times to the onset of first- and second-order motion. The stimuli consisted of luminance-modulated (first-order) and contrast-modulated (second-order) 1 cpd vertical sine-wave gratings drifting rightward for 140 ms at a velocity of 6 degrees /s. For each condition, we analysed the latencies and peak-to-baseline amplitudes of the P1 and N2 peaks recorded at Oz. For first-order motion, both P1 and N2 peaks were present at low (3%) contrast (i.e., depth modulations) whereas for second-order motion they appeared only at higher (25%) contrasts. When the two types of motion were equated for visibility, responses were slower for second-order motion than for first-order motion: about 44 ms slower for P1 latencies, 53 ms slower for N2 latencies, and 76 ms slower for reaction times. The longer VEP latencies for second-order motion support models that postulate additional processing steps for the extraction of second-order motion. The slower reaction time to the onset of second-order motion suggests that the longer neurophysiological analysis translates into slower detection.
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Affiliation(s)
- D Ellemberg
- Groupe de Recherche en Neuropsychologie et Cognition, Université de Montréal, Que., Montréal, Canada
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27
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Stampe DM, Reingold EM. Influence of stimulus characteristics on the latency of saccadic inhibition. PROGRESS IN BRAIN RESEARCH 2003; 140:73-87. [PMID: 12508583 DOI: 10.1016/s0079-6123(02)40043-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Participants read or performed visual search while the normal task display was replaced for 33 ms by a transient image at random intervals. This produced a sharp reduction in saccadic frequency (saccadic inhibition) beginning as early as 70 ms following the display change. It was found that the latency of inhibition onset was determined by the difference between the normal and transient images, with changes in high spatial frequency content of the display resulting in longer latencies than changes in low spatial frequencies. Luminance changes evoked the fastest inhibition onset regardless of the spatial frequency content of the display change.
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Affiliation(s)
- Dave M Stampe
- Department of Psychology, University of Toronto, 100 St. George Street, Toronto, ON M5S 3G3, Canada
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28
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Abstract
We used fast, pseudorandom temporal sequences of preferred and antipreferred stimuli to drive neuronal firing rates rapidly between minimal and maximal across the visual system. Stimuli were tailored to the preferences of cells recorded in the lateral geniculate nucleus (magnocellular and parvocellular), primary visual cortex (simple and complex), and the extrastriate motion area MT. We found that cells took longer to turn on (to increase their firing rate) than to turn off (to reduce their rate). The latency difference (onset minus offset) varied from several to tens of milliseconds across cell type and stimulus class and was correlated with spontaneous or driven firing rates for most cell classes. The delay for response onset depended on the nature of the stimulus present before the preferred stimulus appeared, and may result from persistent inhibition caused by antipreferred stimuli or from suppression that followed the offset of the preferred stimulus. The onset delay showed three distinct types of dependence on the temporal sequence of stimuli across classes of cells, implying that suppression may accumulate or wear off with time. Onset latency is generally longer, can be more variable, and has marked stimulus dependence compared with offset latency. This suggests an important role for offset latency in assessing the speed of information transmission in the visual system and raises the possibility that signal offsets provide a timing reference for visual processing. We discuss the origin of the delay in onset latency compared with offset latency and consider how it may limit the utility of certain feedforward circuits.
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29
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Vassilev A, Mihaylova M, Bonnet C. On the delay in processing high spatial frequency visual information: reaction time and VEP latency study of the effect of local intensity of stimulation. Vision Res 2002; 42:851-64. [PMID: 11927350 DOI: 10.1016/s0042-6989(01)00300-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Saleh and Bonnet [Fechner Day 98, p. 344] have shown that, upon parafoveal stimulation and up to 6.5 c/deg, reaction time (RT) is a function of grating contrast multiplied by grating period. The present experiments extend these findings to foveal stimulation within a wider spatial-frequency (SF) range and to stimuli of different duration. Both RT and latency of visually evoked potentials (VEP) were measured. The findings might be explained by the following assumption: Most RT and VEP latency variations across the SF range are a result of local intensity factors (retinal contrast and width of grating bars). Residual RT variations were found that might be due to processing of high SFs by slower mechanisms than those processing low and medium SFs.
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Affiliation(s)
- Angel Vassilev
- Institute of Physiology, Bulgarian Academy of Sciences, Acad G Bonchev St Bl 23, 1113 Sofia, Bulgaria.
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30
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Morrison DJ, Schyns PG. Usage of spatial scales for the categorization of faces, objects, and scenes. Psychon Bull Rev 2001; 8:454-69. [PMID: 11700896 DOI: 10.3758/bf03196180] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The role of spatial scales (or spatial frequencies) in the processing of faces, objects, and scenes has recently seen a surge of research activity. In this review, we will critically examine two main theories of scale usage. The fixed theory proposes that spatial scales are used in a fixed, perceptually determined order (coarse to fine). The flexible theory suggests instead that usage of spatial scales is flexible, depending on the requirements of visual information for the categorization task at hand. The implications of the theories are examined for face, object, and scene categorization, attention, perception, and representation.
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Affiliation(s)
- D J Morrison
- Department of Psychology, University of Glasgow, Scotland
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31
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Faubert J, Herbert AM. The peripheral drift illusion: a motion illusion in the visual periphery. Perception 2000; 28:617-21. [PMID: 10664757 DOI: 10.1068/p2825] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Circularly repeating patches containing sawtooth luminance gradients produce a sensation of motion when viewed in the periphery. Illusory motion is perceived in a dark-to-light direction, but only when one's gaze is directed to different locations around the stimulus, a point outside the display is fixated and the observer blinks, or when the stimulus is sequentially displayed at different locations whilst the observer fixates one point. We propose that the illusion is produced by the interaction of three factors: (i) introducing transients as a result of eye movements or blinks; (ii) differing latencies in the processing of luminance; and (iii) spatiotemporal integration of the differing luminance signals in the periphery.
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Affiliation(s)
- J Faubert
- Ecole d'Optométrie, Université de Montréal, Québec, Canada.
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32
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McSorley E, Findlay JM. An examination of a temporal anisotropy in the visual integration of spatial frequencies. Perception 2000; 28:1031-50. [PMID: 10664752 DOI: 10.1068/p281031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Three pairs of experiments were conducted to investigate the importance of spatial-frequency-processing delays imposed by the visual system on the efficacy of their subsequent integration. In the first pair of experiments filtered versions of a natural image were found to be easily discriminable from the full-bandwidth image. These images were then placed into triplets and presented sequentially. Subjects were required to detect the presence of a full-bandwidth target image within the sequence. As with previous results a low-to-high progression of spatial-frequency information did increase the number of errors of full-bandwidth-image detection within the triplets where it was not present. However, this was not found across all conditions and was suggested to be due to the increased discriminability of the constituent images which form the image triplets. The second experiment was a repetition of the first with more confusable component images. Again the weak order effect on target detection was found. It was suggested that this may be due to the nature of the stimulus used. The third pair of experiments repeated the design of the first pair of experiments but with Gabor patches which provide localised spatial-frequency information. It was found that a low-to-high progression of spatial frequencies resulted in more false detections of the target. The results are interpreted as supporting an integration mechanism which operates with greater efficacy when the presentation of spatial-frequency information mirrors that naturally imposed by the neural delays involved in the processing of spatial frequencies.
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Affiliation(s)
- E McSorley
- Centre for Vision and Visual Cognition, University of Durham, UK.
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33
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Parker DM, Costen NP. One extreme or the other or perhaps the golden mean? Issues of spatial resolution in face processing. CURRENT PSYCHOLOGY 1999. [DOI: 10.1007/s12144-999-1021-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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34
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Mihaylova M, Stomonyakov V, Vassilev A. Peripheral and central delay in processing high spatial frequencies: reaction time and VEP latency studies. Vision Res 1999; 39:699-705. [PMID: 10341957 DOI: 10.1016/s0042-6989(98)00165-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Visually evoked potentials (VEP) and reaction time (RT) were recorded under stimulation with sinusoidal gratings. Grating spatial frequency (SF) was 0.5, 5 or 12 cd and grating contrast was varied. Consistent with previous findings, both VEP latency and RT increased with the increase of grating SF and with the decrease of grating contrast. It was found, in addition, that RT and VEP latency increased by approximately the same amount when SF increased from 0.5 to 5 cd, thus suggesting that the main source of the RT delay at 5 cd in comparison with RT at 0.5 cd is of peripheral origin. However, in comparison with the data at 0.5 and 5 cd, RT at 12 cd increased much more than VEP latency. We conclude that the RT delay at high SF involves a substantial central component in addition to the peripheral delay.
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Affiliation(s)
- M Mihaylova
- Institute of Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
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35
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Abstract
The global effect in eye orienting occurs when saccades land at the 'centre of gravity' of a target stimulus configuration. Short-latency saccades are particularly prone to this effect whereas longer-latency saccades may show more influence of fine detail. Alternative explanations of these effects are considered and data are presented from an experiment in which the influence of different stimulus features on the global effect in a search task was examined. The effect shows a substantially different time course for target-distractor combinations differing in contrast polarity (black vs white) than for combinations differing in shape (circle vs square). It is concluded that the global effect cannot be explained either as a high-level strategic effect or as an effect of automatic fast processing of low-spatial-frequency information in early sensory channels. Instead it is suggested that the visual-spatial-integration characteristic of the global effect is an integral and unavoidable part of the process of selection of saccadic response.
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Affiliation(s)
- J M Findlay
- Department of Psychology, University of Durham.
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36
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Parker DM, Lishman JR, Hughes J. Evidence for the view that temporospatial integration in vision is temporally anisotropic. Perception 1998; 26:1169-80. [PMID: 9509151 DOI: 10.1068/p261169] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In two experiments low-pass and high-pass spatially filtered versions of a base image were prepared and the effect of the order of delivery of sequences of filtered and base images investigated. A task that required subjects to discriminate 120 ms presentations of a full-bandwidth base image and degraded sequences that contained sets of three different spatially filtered versions, or mixtures of spatially filtered and full-bandwidth versions of the image, were used. Each set of images used in the degraded sequences was presented either so that within the 120 ms presentation window the spatial content swept from low to high spatial frequencies or from high to low. In experiment 1 twenty subjects discriminated between a base image and degraded sequences of an urban scene. Results showed both a significant overall effect of image order, with low-to-high spatial-frequency information delivery being mistaken more often for the full-bandwidth presentation than high-to-low, and that different sets of degraded image sequences varied significantly in the frequency with which they were mistaken for the full-bandwidth presentation. In experiment 2 a base and filtered versions of a human face were used in an identical task with twenty different subjects and a very similar pattern of significant results was obtained, although imposed on a lower overall error frequency than that obtained in experiment 1. It was concluded that the results of both experiments provide evidence for an anisotropic temporospatial integration mechanism in which availability of spatial information in a low-to-high spatial-frequency sequence results in more efficient integration than a high-to-low.
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Affiliation(s)
- D M Parker
- Department of Psychology, Glasgow Caledonian University, UK
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37
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Abstract
It has long been known that people who have high scores on intelligence tests are also relatively fast at simple laboratory tests of ‘mental speed’ (Woodrow, cited in Woodworth, 1946). When first observed these correlations attracted little interest because, though ubiquitous, they are very modest, accounting for only 3–9% of variance between individuals (Sternberg, R. J., 1977). Correlations between intelligence test scores (TSs) and speed of performance on simple tasks were seen as less interesting than equally strong associations between TSs and performance on simple tests of memory and learning (Woodrow, 1938). The idea that intelligence can be defined as the capacity to learn new skills seemed a more fruitful guide to the development of individual differences in competence (Woodrow, 1946). Further, since scores on most intelligence tests represent the number of problems correctly solved within a time limit, it did not seem remarkable that people who can solve complex problems quickly should also be able to make simple decisions fast. Finally, evidence accumulated that, speed and accuracy of problem solving can be independent; for example, the times that individuals take to solve complex spatial problems do not predict their error-rates (Egan, 1978). Consequently mental speed was seen as only one of many different demands that solving intelligence test problems make on the cognitive system. Many distinguished investigators believe that better insights can be gained into the nature of individual differences in intellectual ability by studying correlations between TSs and performance on complex tasks that demand the encoding, organisation and transformation of information in working memory or successive stages in syllogism solution (e.g. Carpenter & Just, 1989; Daneman & Carpenter, 1980; Kyllonen & Crystal, 1990; Necka, 1992; Sternberg, R. J., 1977).
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Affiliation(s)
- P Rabbitt
- University of Manchester, Age and Cognitive Performance Research Centre
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38
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Vassilev A, Stomonyakov V, Manahilov V. Spatial-frequency specific contrast gain and flicker masking of human transient VEP. Vision Res 1994; 34:863-72. [PMID: 8160399 DOI: 10.1016/0042-6989(94)90036-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We studied the effects of grating contrast and luminance-flicker masking on the early waves of human visually evoked potentials (VEPs) recorded at the onset-offset of sinusoidal gratings of varying spatial frequencies (SFs). At high SFs, the response waveform was simple and VEP was dominated by a negative wave (N110). At low SFs, several positive-negative deflections were recorded, the earliest dominating wave being positive (P90). The amplitude of P90 was saturated at a contrast of about 0.1 and it was attenuated by flicker masking. Masking involved to a lesser extent the waves following P90. It was weaker at the flicker frequency of 5 Hz than at 10 and 20 Hz. No flicker masking was found at SFs higher than 2-4 c/deg. At medium and high SFs, VEPs were obtained at higher contrast levels. No saturation (max contrast tested 0.5) and no flicker masking of N110 were observed. These results suggest that the early VEP components recorded at low and high SFs are related to different types of neuronal activity. Correlation between VEP properties and properties of magnocellular and parvocellular pathways is considered with an emphasis on recent morphological data about the human retina.
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Affiliation(s)
- A Vassilev
- Institute of Physiology, Bulgarian Academy of Sciences, Sofia
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39
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Tappe T, Niepel M, Neumann O. A dissociation between reaction time to sinusoidal gratings and temporal-order judgment. Perception 1994; 23:335-47. [PMID: 7971110 DOI: 10.1068/p230335] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effect of the spatial frequency (SF) of visual gratings on reaction time (RT) and temporal-order judgment (TOJ) was examined in three experiments. In experiment 1 the visual stimuli were vertical sinusoidal gratings with SFs between 2 and 8 cycles deg-1 and the comparison stimulus in the TOJ task was a 2300 Hz tone. Whereas SF had a highly significant effect on RT, it left TOJ completely unaffected. To test whether this dissociation was due to the sharp (high SF) horizontal edges of the gratings, a second experiment was carried out with circular stimuli with no sharp edges. These stimuli did produce an effect of SF on TOJ, but it was significantly smaller than was the effect on RT. In experiment 3 we confirmed that this difference was not due to differences in grating orientation between the first two experiments. These findings (a) solve discrepancies between findings reported in the literature and (b) strongly suggest that RT and TOJ cannot be regarded as converging operations for determining 'visual latency'. This dissociation can best be accounted for by assuming that the output of early stimulus analysis can feed directly into the motor system (direct parameter specification), whereas the conscious representation that is used for TOJ is based on later integrative processes.
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Affiliation(s)
- T Tappe
- Department of Psychology, University of Bielefeld, Germany
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40
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Abstract
This study shows that there are delays in processing high spatial frequencies relative to low frequencies, and that these may affect the perceived brightness profile of drifting waveforms. The stimuli were complex waveforms consisting of 2-3 sinusoidal components, either drifting or stationary. The phase of the components was varied until the brightness profile of the waveform appeared as a square, triangle, ramp or bar. The results indicate that stationary waveforms are perceived veridically, but drifting waveforms are not. The harmonics of a drifting complex wave must be phase advanced, relative to the fundamental, in order to cancel motion-induced waveform distortions. This suggests that during visual processing the harmonics must be phase delayed, indicating that they are being processed more slowly than the fundamental. The most significant delays appear to be those between the fundamental and its second and third harmonic. Furthermore, the results show that the magnitude of the delays is dependent on the phase relationship between the components at perceptually significant points in the waveform: delays are less when the components are in sine phase than when they are in cosine phase. Separate experiments show that the detectability of phase shifts is least when the components are in sine phase. Together, these results may explain why drifting "sharp-edged" stimuli are not perceptually distorted: the human visual system appears to be relatively insensitive to phase shifts around square-wave phase and may therefore tolerate differences in the processing times of certain harmonics. A discussion of the possible origin of these processing delays is presented, together with the hypothesis that frequency dependent delays may reflect the spatiotemporal inseparability of cortical visual units.
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Affiliation(s)
- S J Anderson
- Department of Vision Sciences, Aston University, Birmingham, England
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41
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Suter PS, Bass BL, Suter S. Early and late VEPs for reading stimuli are altered by common binocular misalignments. Psychophysiology 1993; 30:475-85. [PMID: 8416074 DOI: 10.1111/j.1469-8986.1993.tb02071.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Effects of mild binocular anomalies on early and late evoked response complexes to word stimuli were examined in visual evoked potentials (VEPs) recorded over occipital cortex, Wernicke's area, and its right side homolog in university students with (fixation disparity group) and without (normal group) fixation disparity. Stimuli were monocularly or binocularly viewed words of a paragraph presented individually for 100 ms, one per second, and a binocular control condition without linguistic content. An early complex (P125-N170) recorded at Oz and a late complex (N170-late P) recorded from the temporoparietal placements were analyzed. The early complex was not influenced by linguistic content. Binocular stimuli generally resulted in larger early and late VEP amplitudes than did monocular stimuli except that the fixation disparity group had no binocular amplitude enhancement at Oz. Left hemisphere amplitude was greater than right for all conditions, more so for words than for nonlinguistic stimuli. For words, the left hemisphere advantage was significant only for the normal group. Relationships between basic visual processing and language processing in relation to early and late complexes are considered from several perspectives.
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Affiliation(s)
- P S Suter
- Department of Psychology, California State University, Bakersfield 93311
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42
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Abstract
Spatially localized, contrast modulated visual stimuli evoke a monophasic, inion negative scalp potential (VEP) which can be recorded simultaneously with motor responses in simple reaction time experiments. VEP response time and median motor response latency are linearly related over a wide range of stimuli. We interpret our results to suggest that VEPs and motor response latencies arise from a common sensory system with different thresholds for detection and reaction. A model is introduced to predict detection thresholds from VEP response times which are usually more robust measures than VEP amplitudes.
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Affiliation(s)
- R C Hartwell
- Department of Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia 19104
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43
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Abstract
Grating acuity was measured in 16-week-old human infants. Three measurement techniques were used: forced-choice preferential-looking (FPL), and two visual-evoked-potential (VEP) techniques. The stimuli were counterphase flickering sinewave gratings with a space-average luminance of -1.0 or 2.0 log cd/m2. Slightly different luminance-dependent changes occur between FPL and VEP acuities, suggesting that some factor influences the two methods differently as stimulus luminance varies. A comparison between FPL acuities and VEP acuities within infants suggests a quantitative relationship between techniques. Infant's acuity for sinewave gratings with a space-average luminance of -2.0, -1.0, 0.0, 1.0 and 2.0 log cd/m2 was also measured using a single VEP paradigm. The results are compared to the same measurements in adults and to infant and adult ideal observers. VEP acuity in this group of infants improves by about 0.5 log units between -2.0 and 0.0 log cd/m2 and remains asymptotic between 0.0 and 2.0 log cd/m2. This result suggests that luminance-dependent changes in infant acuity cannot be fully accounted for by immaturities in the optics and photoreceptor spacing and efficiency.
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Affiliation(s)
- D Allen
- School of Optometry and Department of Psychology, University of California, Berkeley 94720
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44
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Hughes J, Lishman JR, Parker DM. Apparent duration and spatial structure. PERCEPTION & PSYCHOPHYSICS 1992; 52:222-30. [PMID: 1508629 DOI: 10.3758/bf03206775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In three experiments, we investigated the relative perceived duration of a full bandwidth image and a set of high- and lowpass filtered images of a scene, briefly presented on a visual display unit. In Experiment 1, the various images were compared with each other, using a paired comparison method. All images were presented for 40 msec, and observers were asked to judge which of each pair of images had the longest duration. The results showed that images containing a wide spatial frequency bandwidth were judged to be of longer duration than were images of a narrower bandwidth, regardless of whether the latter were high- or lowpass filtered. In Experiment 2, a 40-msec presentation of each of the images was compared with a presentation of a probe that was 20, 40, 60, or 80 msec in duration. Observers again judged which of each pair of images had the longest duration. The results were very similar to those of Experiment 1, with wide bandwidth images being judged to be of longer duration than were narrow bandwidth images. In Experiment 3, instead of comparing the various filtered versions of the image with each other, we attempted to obtain a direct measure of perceived duration by comparing a flashing LED to a 40-msec flash of a subset of the images used in the previous experiments. The observers' task was to adjust the duration of the LED flash to match the perceived duration of each image.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Hughes
- King's College, University of Aberdeen, Scotland
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45
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Grossberg S, Merrill JW. A neural network model of adaptively timed reinforcement learning and hippocampal dynamics. ACTA ACUST UNITED AC 1992; 1:3-38. [PMID: 15497433 DOI: 10.1016/0926-6410(92)90003-a] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A neural model is described of how adaptively timed reinforcement learning occurs. The adaptive timing circuit is suggested to exist in the hippocampus, and to involve convergence of dentate granule cells on CA3 pyramidal cells, and N-methyl-D-aspartate (NMDA) receptors. This circuit forms part of a model neural system for the coordinated control of recognition learning, reinforcement learning, and motor learning, whose properties clarify how an animal can learn to acquire a delayed reward. Behavioral and neural data are summarized in support of each processing stage of the system. The relevant anatomical sites are in thalamus, neocortex, hippocampus, hypothalamus, amygdala and cerebellum. Cerebellar influences on motor learning are distinguished from hippocampal influences on adaptive timing of reinforcement learning. The model simulates how damage to the hippocampal formation disrupts adaptive timing, eliminates attentional blocking and causes symptoms of medial temporal amnesia. Properties of learned expectations, attentional focussing, memory search and orienting reactions to novel events are used to analyze the blocking and amnesia data. The model also suggests how normal acquisition of subcortical emotional conditioning can occur after cortical ablation, even though extinction of emotional conditioning is retarded by cortical ablation. The model simulates how increasing the duration of an unconditioned stimulus increases the amplitude of emotional conditioning, but does not change adaptive timing; and how an increase in the intensity of a conditioned stimulus 'speeds up the clock', but an increase in the intensity of an unconditioned stimulus does not. Computer simulations of the model fit parametric conditioning data, including a Weber law property and an inverted U property. Both primary and secondary adaptively timed conditionings are simulated, as are data concerning conditioning using multiple interstimulus intervals (ISIs), gradually or abruptly changing ISIs, partial reinforcement and multiple stimuli that lead to time-averaging of responses. Neurobiologically testable predictions are made to facilitate further tests of the model.
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Affiliation(s)
- S Grossberg
- Center for Adaptive Systems and Department of Cognitive and Neural Systems, Boston University, Boston, MA 02215, USA
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46
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Parker DM, Lishman JR, Hughes J. Temporal integration of spatially filtered visual images. Perception 1992; 21:147-60. [PMID: 1513664 DOI: 10.1068/p210147] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Factors which govern the temporal integration of spatial information were examined in a group of five experiments. A series of high-pass and low-pass spatially filtered versions of a visual scene were generated. Observers' ratings of these filtered versions of the scene for perceived image quality indicated that quality was determined both by the bandwidth of spatial information and the presence of high-spatial-frequency edge information. When sequences of three different versions of the scene were presented over an interval of 120 ms the perceived quality of the resulting composite image was determined both from the ratings of the individual components of that sequence and from the order in which these components were presented. When the order of spatial information in a sequence moved from coarse to fine detail the perceived quality of the composite image was significantly better than when the order moved from fine to coarse. This evidence of a coarse-to-fine bias in pattern integration was further investigated with a detection paradigm. The pattern of errors once again indicated that temporal integration of spatial information was superior when a coarse-to-fine mode of information delivery was employed. Taken together the data indicate that the pattern-integration mechanism has an inherent order bias and does not accumulate spatial information so efficiently when the 'natural' coarse-to-fine order is violated.
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Affiliation(s)
- D M Parker
- Department of Psychology, Kings College, University of Aberdeen, Scotland
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47
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Abstract
Since visible persistence of grating patterns increases with spatial frequency, it is often inferred that the perceived duration of a grating is also longer at higher spatial frequencies. However, other work has demonstrated that the perceived onset of a grating is also delayed at higher spatial frequencies. Thus it is impossible to infer the subjective duration from the results of visible persistence studies alone. In order to estimate perceived duration in the present study, reaction times (RTs) to grating onsets and offsets were measured for a range of spatial frequencies. The results indicate that although the perceived duration (ie the difference between offset and onset RTs) was consistently longer than the physical duration, the estimates of perceived duration did not vary with changes in spatial frequency. Differences between the present results and earlier findings are interpreted in the context of the different methods used to measure perceived offset.
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Affiliation(s)
- J A Baro
- School of Optometry, University of Missouri-St Louis 63121
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48
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Jakobsson P, Johansson B. The effect of spatial frequency and contrast on the latency in the visual evoked potential. Doc Ophthalmol 1992; 79:187-94. [PMID: 1591972 DOI: 10.1007/bf00156577] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The latency in the visual evoked potential was measured at spatial frequencies of 2-12 c/deg in 10 subjects. The contrast levels of the sinuosoidal grating patterns were set at 1.5, 1.75, 2.0, 2.25, 2.5, 2.75 and 3.0 log units above each subject's contrast sensitivity threshold. Two factors were shown to influence the latency: suprathreshold contrast and, to a lesser extent, spatial frequency. The visual evoked potential latencies at contrast sensitivity threshold were extrapolated. These threshold latencies showed considerable variation with spatial frequency and between subjects. Therefore, the visual evoked potential latency cannot be considered a useful tool for estimating the contrast sensitivity function.
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Affiliation(s)
- P Jakobsson
- Department of Ophthalmology, University Hospital, Linköping University, Sweden
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49
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50
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The ups and downs of visual fields. Behav Brain Sci 1990. [DOI: 10.1017/s0140525x00080109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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