Michael von Grünau
Contact | Education | Research| Publications| Conferences
Michael von Grünau
Department of Psychology
Concordia University
7141 Sherbrooke St. West
Montreal, Quebec, Canada, H4B 1R6
M.A. in Psychology (U. of Toronto) 1971
Ph.D. in Psychology (U. of Toronto) 1975
I am looking for a beginning graduate student at the Master’s level (expected to lead to the PhD) for the Fall of 2010. Project may be chosen from many topic areas that are currently pursued in the lab.
Higher-order motion aftereffects
Motion aftereffects (MAEs) evoked by first-order and various types of second-order stimuli are studied with stationary and dynamic test stimuli. We developed a measuring technique using counterphase gratings with variable contrast difference of the components to estimate the MAE strength. We are also looking at eccentricity-scaling of the various types of MAE and attentional modification of the magnification factors.
Visual search and attention in the real world
We have studied visual search to specific ecologically important stimulus aspects, such as the direction of human gaze or the viewing direction with respect to objects. We are interested also in search when the search items are embedded in particular backgrounds in a meaningful or not meaningful way, or when the backgrounds are very large. Eye movement indicators are used along with response time and accuracy.
The role of selection in early perception
We are studying selection of a location in visual space, of a visual attribute (such as color vs motion), or of a perceptual property within an attribute (such as first- vs second-order motion). Using the illusion of motion induction, we have shown the existence of selective processes at many levels (such as due to stimulus saliency, attentional capture, visual search, or expectancy). Using the motion aftereffect, we study how attentional or non-attentional selection can influence the strength of the MAE.
Visual Flow Fields
We are interested in studying mainly radial and planar flowfields and their combinations. We have underway a number of psychophysical projects that address the extent of the spatial and temporal summation properties of the mechanisms that encode image flow. We measure these spatial and temporal parameters by varying stimulus area and dot lifetimes and presentation times to find asymptotic direction discrimination thresholds. A second approach to investigate the spatial integration is through studies of motion aftereffects (MAEs). We are also examining the effects of manipulating dot lifetime, velocity, velocity gradient, perspective information, dot density, number of dots, spatial distribution of coherent and non-coherent portions on the biologically relevant properties. A specific case is the addition of eye movement-produced planar motion to locomotion-produced radial flow. Accurate radial flow information is needed to extract heading information. Can the system filter out the planar component by using visual information alone (rather than eye movement feedback)?
Eye movements
In the Vision Lab, we have several eye trackers, which allow us to record eye movements very accurately. We are currently examining pursuit movements of objects in simple and complex flow fields and correlate this with the perceived and actual paths. We are also recording eye, head and body movements during locomotion with different visual tasks to see how locomotion-produced head movements are or are not compensated by eye or other head movements. We are also interested in using eye direction to indicate perceived direction of certain flow field illusions. Furthermore, eye movements during attentional tasks are studied in bottom-up and top-down setups, using saccadic latency and fixational micro-saccades as indicators for attention deployment.
RECENT PUBLICATIONS (Please note: The downloadable files are in Adobe pdf format.)
Galera C., Lopes E.J. and von Grünau M.W. (2000). Stimulus segmentation in the visual search task. Perception & Psychophysics, 62, 505-516.
Haghighat F., Sakr W., Gunnarsen L. and von Grünau M.W. (2001). The impact of combinations of building materials and intermittent ventilation on perceived air quality. ASHRAE Transactions107, Part 1, 1-15.
Iordanova M. and von Grünau M.W. (2001). Asymmetrical masking between radial and parallel motion flow in transparent displays. In: Progress in Brain Research, special edition: From Neurons to Cognition, 134, 333-352.
von Grünau M.W. (2002). Bivectorial transparent stimuli simultaneously adapt mechanisms at different levels of the motion pathway. Vision Research, 42, 577-587.
von Grünau M.W., Panagopoulos A., Galera C. and Savina O. (2002). Visual search with exogenous and endogenous cueing. Proceedings of the International Psychophysical Society, 18, 225-230.
von Grünau M.W. and Iordanova M. (2004). A visual mechanism for extraction of heading information in complex flow fields. In: Vaina L.M., Beardsley S.A. & Rushton S. (Eds.) Optic Flow and Beyond. Kluwer Academic Publishers, Netherlands, Ch. 3, pp 45-59.
Panagopoulos A., von Grünau M.W., and Galera C. (2004). Attentive mechanisms in visual search. Spatial Vision, 17, 353-371.
Galera C., von Grünau M.W. and Panagopoulos A. (2004). Size and shape of the attentional spotlight affect efficiency of processing. In: Oliveira, A.M., Teixeira, M.P., Borges, G.F., & Ferro, M.J. (Eds). Fechner Day 2004, Proceedings of the International Psychophysical Society, 20, 368-373.
Cavanagh, P., von Grünau, M., & Zimmerman, L. (2004). View dependence of 3D recovery from folded pictures and warped 3D faces. IEEE Proceedings of the 2nd International Symposium on 3D Data Processing, Visualization, and Transmission, 35-41.
Lacroix G., Constantinescu I., Cousineau D., de Almeida R., Segalowitz N. and von Grünau M.W. (2005). Attentional blink differences between adolescent dyslexic and normal readers. Brain & Cognition, 57, 115-119.
Galera C., von Grünau M.W. and Panagopoulos A. (2005). Automatic focusing of attention on object size and shape. Psychológica, 26, 147-160.
Lacroix, G. L., Segalowitz, N., von Grünau, M., Gurnsey, R., de Almeida, R. G., Borokhovski, E., Wada, N., & Constantinescu, I. (2005). Sciences cognitives appliquées et habiletés langagières de base. In S. Pierre (ed.) Innovations et tendances en technologies de formation et d‚apprentissage (pp. 521-540). Montreal, Quebec : Presses Internationales Polytechnique.
Galera C, Cavallet M., von Grünau M. and Panagopoulos A. (2006). Attentive characteristics revealed by local and global multiple cues. Psicologia: Teoria e Pesquisa, 22, 327-334.
Vavassis A. and von Grünau M.W. (2007). Complex backgrounds delay low-load visual search. Spatial Vision. 20, 467-488.
von Grünau M.W., Pilgrim K. & Zhou R. (2007). Velocity discrimination thresholds for flowfield motions with moving observers. Vision Research, 47, 2453-2464.
Zhou R., Johnson A., Gurnsey R. and von Grünau M.W. (2008). Visual performance in normal and simulated low vision. Proceedings of the 9th International Conference on Low Vision, Montreal, July, 2008.
de Almeida R. G., Di Nardo J. C., & von Grünau M. W. (submitted; under review). Understanding sentences in dynamic scenes: linguistic and visual processes are independent.
von Grünau M.W., Galera C., Panagopoulos A. and Cavallet M. (2006). Exogenous attention distorts visual space and speeds up processing. Paper presented at VSS Annual Meeting in Sarasota, Fla.
Panagopoulos A., von Grünau M.W., Galera C., Ivan L. and Cavallet M. (2006). Does the strength of the attentional focus depend on the size of the cued area? Paper presented at VSS Annual Meeting in Sarasota, Fla.
Vavassis A. and von Grünau M.W. (2006). Practice-induced improvements for target detection in rapidly presented visual search displays is temporal-context dependent. Paper presented at VSS Annual Meeting in Sarasota, Fla.
Galera C., Cavallet M., von Grünau M.W., Caserta G. and Panagopoulos A. (2006). The distribution of visual attention: evidence based on temporal order judgment (TOJ) task. Paper presented at VSS Annual Meeting in Sarasota, Fla.
Desjardins S. and von Grünau M.W. (2006). Quantification et inversement de l’illusion de Duffy et Wurtz. Paper presented at ACFAS Annual Meeting, Montreal, Qué.
Lacroix, G. L., Constantinescu, I., Segalowitz, N., de Almeida, R. G., & von Grünau, M. (2006). The relation between semantic memory and the attentional blink. 47th Annual Psychonomic Society Meeting, Houston, Texas, November 16-19, 2006.
von Grünau M.W. and Zhou R. (2007). Compensation of the effects of eye and head movements during walking and running. Paper presented at VSS Annual Meeting in Sarasota, Fla.
Vavassis A. and von Grünau M.W. (2007). Visual-spatial perceptual learning is specific to the context of trained stimulus display durations. Paper presented at VSS Annual Meeting in Sarasota, Fla.
von Grünau M.W. and Zhou R. (2007). Visual task performance with walking and running observers. Paper presented at ECVP’07 in Arezzo, Italy.
Stockall L., de Almeida R.G., von Grünau M.W., Guay A., Petropoulou A. & Sodo D. (2007). Early Compound Constituent Processing by the Two Hemispheres: Behavioral and MEG Evidence. Paper presented at the 13th International Morphology Meeting, Vienna, Austria.
von Grünau M.W., Engarhos P. and Bacchus Z. (2008). Motion aftereffect and motion fading: Same underlying mechanisms? Paper presented at VSS Annual Meeting in Naples, Fla.
Zhou R., Johnson A., Gurnsey R. and von Grünau M.W. (2008). Eye Movement Strategies: A Comparison between Individuals with Normal Vision and Simulated Scotomas. Paper presented at VSS Annual Meeting in Naples, Fla.
Iordanova-Maximow M. and von Grünau M.W. (2008). Visual velocity aftereffects in radial flow: inherited and unique features. Paper presented at VSS Annual Meeting in Naples, Fla.
Zhou R., Johnson A., Gurnsey R. and von Grünau M.W. (2008). Visual Performance in Normal and Simulated Low Vision. Paper presented at 9th International Conference on Low Vision, Montreal, Qué.
Zhou, R. and von Grünau, M. W. (2008). Eye movement patterns: 3D shape discrimination in the periphery. Presented at Réseau de recherche en santé de la vision, Vision Network Annual Meeting. Montréal, Québec, Canada.
Robitaille, N., Grohmann, B., Zhou, R. and von Grünau, M. W. (2009). The effects of product display organization or consumer’s visual attention to attributes. Presented at Society for Consumer Psychology Annual Winter Conference.
von Grünau M.W., Manescu S., Sadi R. and Zhou R. (2009). The relationship between eye and head movements during locomotion with visual pursuit tasks. Paper presented at VSS Annual Meeting in Naples, Fla.
Zhou R., von Grünau M.W., Johnson A. and Gurnsey R. (2009). Simulated low vision with young and old adults: How do they see? Paper presented at VSS Annual Meeting in Naples, Fla.
Cavallet M., Galera C., von Grünau M.W., Panagopoulos A. and Leão E. (2009). The size of the cued area does not affect scaling of attentional focus on temporal order judgment task. Paper presented at VSS Annual Meeting in Naples, Fla.
Cavallet M., Galera C., von Grünau M.W. & Aaron Johnson (2009). The adjustment of the focus of visual attention is determined at early levels of processing. Presented at ECVP’09 in Regensburg, Germany.
von Grünau M.W., Sadi R., Manescu S. & Zhou R. (2009). Vertical and horizontal eye and head movements during locomotion and simultaneous stimulus pursuit. Presented at ECVP’09 in Regensburg, Germany.
Zhou R., von Grünau M.W., Johnson A. & Gurnsey R. (2009). The effect of different artificial central scotomata on eye-movement patterns. Presented at ECVP’09 in Regensburg, Germany.