The proposed experiments seek to characterize the capacity of the visual system for transmitting sensory information. The approach is both at a high level, by studying visual attention, and at a low level, by measuring intrinsic noise. The work on attention, Aim 1, addresses the """"""""span of attention"""""""" conjecture that attention is mediated by a general-purpose processor with a data capacity of only 45 bits (Verghese and Pelli, 1991). This will be tested by measuring the data capacity for identifying words and reading. The data capacity of the display will be restricted by blur and added noise, to find the lowest data capacity that allows unimpeded reading. The results will either disprove the span-of-attention conjecture, by finding a higher data capacity, or confirm it, showing that reading rate is bounded by the fixed data capacity of visual attention. The intrinsic noise measurements of Aims 2 and 3 borrow a technique from electrical engineering. Noise will be presented as a visual stimulus, and measured effects of that noise will be used to infer the characteristics of the intrinsic noise, expressed as an equivalent input noise.
Aim 2 is a psychophysical survey of the spatiotemporal spectrum of the equivalent noise as a function of luminance and retinal eccentricity for rods and cones.
Aim 3 is a physiological measurements of the equivalent noise in cat ganglion cells. The results of Aims 2 and 3 will provide a thorough description of the properties of the intrinsic noise, which may then be incorporated into models of visual sensitivity.
| Rosen, Sarah; Pelli, Denis G (2015) Crowding by a repeating pattern. J Vis 15:10 |
| Song, Shuang; Levi, Dennis M; Pelli, Denis G (2014) A double dissociation of the acuity and crowding limits to letter identification, and the promise of improved visual screening. J Vis 14:3 |
| Rosen, Sarah; Chakravarthi, Ramakrishna; Pelli, Denis G (2014) The Bouma law of crowding, revised: critical spacing is equal across parts, not objects. J Vis 14:10 |
| Pelli, Denis G; Cavanagh, Patrick (2013) Object recognition: visual crowding from a distance. Curr Biol 23:R478-9 |
| Suchow, Jordan W; Pelli, Denis G (2013) Learning to detect and combine the features of an object. Proc Natl Acad Sci U S A 110:785-90 |
| Pelli, Denis G; Bex, Peter (2013) Measuring contrast sensitivity. Vision Res 90:10-4 |
| Dubois, Matthieu; Poeppel, David; Pelli, Denis G (2013) Seeing and hearing a word: combining eye and ear is more efficient than combining the parts of a word. PLoS One 8:e64803 |
| Freeman, Jeremy; Chakravarthi, Ramakrishna; Pelli, Denis G (2012) Substitution and pooling in crowding. Atten Percept Psychophys 74:379-96 |
| Chakravarthi, Ramakrishna; Pelli, Denis G (2011) The same binding in contour integration and crowding. J Vis 11: |
| Chakravarthi, Ramakrishna; Cavanagh, Patrick (2009) Bilateral field advantage in visual crowding. Vision Res 49:1638-46 |
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