Spatiotemporal integration of spatial frequencies

Abstract

Spatial frequency processing delays suggest that their integration occurs from coarse to fine. However it may be the case that integration is flexible. The first aim of this thesis was to examine the integration of spatial frequencies and the second was to examine the delays involved in initial spatial frequency processing. A coarse to fine and a fine to coarse presentation order of filtered natural images were shown. The former is judged to be of a higher quality (experiment 1) but neither show any increase in incorrect detection reports of a fullbandwidth image (experiment 2, 3 and 4). When the first three harmonics of a square-wave were shown progressively from coarse to fine and fine to coarse the former leads to more incorrect detection reports of a square-wave (experiment 5) but the latter is favoured in judgements of square-wave resemblance (experiment 6, 8, 9a and 9b), a masking (experiment 10) and a Vernier acuity task (experiment 12). These results suggest that the integration of spatial frequencies is flexible. Despite this, the integration of spatial frequencies must occur from coarse to fine because of the delays involved in the processing of spatial frequencies. In Chapter 6 (experiments 13 - 18) it was found that two widely different spatial frequencies were judged to have simultaneous onset when they were in fact simultaneous. The results of this thesis provided evidence that the integration of spatial frequencies is flexible and dependent upon the information to be derived by any particular processing. The lack of evidence for spatial frequency processing delays suggest that a flexible integration of spatial frequencies may be possible when spatial frequencies are presented simultaneously.