TEXTURE DENSITY ADAPTATION AND THE PERCEIVED NUMEROSITY AND DISTRIBUTION OF TEXTURE

Three experiments were conducted to assess the impact of adaptation to dense visual texture on the perceived numerosity and spatial distribu tion of texture. Study participants compared fields of dots presented in 2 locations, 1 of which was adapted to dense arrays of dots. The ef fect of adaptation was assessed by measuring points of subjective equa lity between the adapted and unadapted regions for the perceived densi ty, numerosity, and distribution (cluster) of texture with staircase p rocedures for textures containing 20-320 dots. Perceived texture densi ty was reduced at all numerosities. For high numerosities, density ada ptation markedly diminished the perceived numerosity but not the appar ent cluster of the dots. At low numerosities, the opposite pattern of results emerged, suggesting that density is more influential in the pe rception of high numerosities and that perceptual distortions of numbe r and cluster may be traded off with one another. A simulation study o f Allik and Tuulmets's (1991) occupancy model of perceived numerosity is also presented, and suggestions are made for modifying the model ba sed on the patterns of results found.