Abstract
Recognition of phantom objects—those with contours defined by rapid contrast reversal of adjacent fields of dark and light random dots—was investigated under conditions of abrupt or ramped onset and offset. Discrimination contrast thresholds were determined for a random-dot phantom letter in four possible orientations. For abrupt onset or offset, thresholds were almost independent of the duration of presentation time, over a range that varied tenfold, from 34–340 msec. However, when the onset and offset were shaped by a triangular envelope, thresholds were raised, so that form blindness occurred even when peak dot contrasts exceeded 60%. Also under ramped onset and offset conditions, threshold contrast varied strictly linearly with stimulus duration in all subjects, suggesting a new construct—contrast velocity, the rate of change of contrast critical for phantom-object recognition.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Barnard, N., Crewther, S. G., &Crewther, D. P. (1998). Development of a magnocellular function in good and poor primary schoolage readers.Optometry & Vision Science,75, 62–68.
Beaudot, W. H. A. (2002). Role of onset asynchrony in contour integration.Vision Research,42, 1–9.
Bullier, J. (2001). Integrated model of visual processing.Brain Research Reviews,36, 96–107.
Crewther, S. G., Crewther, D. P., Klistorner, A., &Kiely, P. M. (1999). Development of the magnocellular VEP in children: Implications for reading disability.Electroencephalography & Clinical Neurophysiology,49(Suppl.), 123–128.
Dakin, S. C., &Bex, P. J. (2002). Role of synchrony in contour binding: Some transient doubts sustained.Journal of the Optical Society of America A,19, 678–686.
Eckhorn, R., Bauer, R., Jordan, W., Brosch, M., Kruse, W., Munk, M., &Reitboeck, H. J. (1988). Coherent oscillations: A mechanism of feature linking in the visual cortex? Multiple electrode and correlation analyses in the cat.Biological Cybernetics,60, 121–130.
Fahle, M. (1993). Figure-ground discrimination from temporal information.Proceedings: Biological Sciences,254, 199–203.
Gray, C. M. (1999). The temporal correlation hypothesis of visual feature integration: Still alive and well.Neuron,24, 31–47, 111–125.
Hupé, J. M., James, A. C., Payne, B. R., Lomber, S. G., Girard, P., &Bullier, J. (1998). Cortical feedback improves discrimination between figure and background by V1, V2 and V3 neurons.Nature,394, 784–787.
Kiper, D. C., Gegenfurtner, K. R., &Movshon, J. A. (1996). Cortical oscillatory responses do not affect visual segmentation.Vision Research,36, 539–544.
Klistorner, A., Crewther, D. P., &Crewther, S. G. (1997). Separate magnocellular and parvocellular contributions from temporal analysis of the multifocal VEP.Vision Research,37, 2161–2169.
Kreiter, A. K., &Singer, W. (1996). Stimulus-dependent synchronization of neuronal responses in the visual cortex of the awake macaque monkey.Journal of Neuroscience,16, 2381–2396.
Laycock, R., Crewther, S. G., &Crewther, D. P. (2007). A role for the “magnocellular advantage” in visual impairments in neurodevelopmental and psychiatric disorders.Neuroscience & Biobehavioral Reviews,31, 363–376.
Lee, S. H., &Blake, R. (2001). Neural synergy in visual grouping: When good continuation meets common fate.Vision Research,41, 2057–2064.
Leonards, U., Singer, W., &Fahle, M. (1996). The influence of temporal phase differences on texture segmentation.Vision Research,36, 2689–2697.
Maunsell, J. H. R., &Gibson, J. R. (1992). Visual response latencies in striate cortex of the macaque monkey.Journal of Neurophysiology,68, 1332–1344.
Ramachandran, V. S., &Rogers-Ramachandran, D. C. (1991). Phantom contours: A new class of visual patterns that selectively activates the magnocellular pathway in man.Bulletin of the Psychonomic Society,29, 391–394.
Rogers-Ramachandran, D. C., &Ramachandran, V. S. (1998). Psychophysical evidence for boundary and surface systems in human vision. Vision Research,38, 71–77.
Simpson, T., &Flanagan, J. G. (1992). A contour illusion letter test [Abstract].Investigative Ophthalmology & Visual Science,33(4), 1385.
Usher, M., &Donnelly, N. (1998). Visual synchrony affects binding and segmentation in perception.Nature,394, 179–182.
Wallis, G. (2005). A spatial explanation for synchrony biases in perceptual grouping: Consequences for the temporal-binding hypothesis.Perception & Psychophysics,67, 345–353.
Author information
Authors and Affiliations
Corresponding author
Additional information
This work was supported by Grant A000937 from the Australian Research Council.
Rights and permissions
About this article
Cite this article
Kiely, P.M., Crewther, S.G. & Crewther, D.P. Threshold recognition of phantom-contour objects requires constant contrast velocity. Perception & Psychophysics 69, 1035–1039 (2007). https://doi.org/10.3758/BF03193941
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.3758/BF03193941