October 2003
Volume 3, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   October 2003
I WILL use the channel I want: flexible spatial scale processing
Author Affiliations
  • Emre Özgen
    University of Surrey, UK
  • Paul T Sowden
    University of Surrey, UK
  • Philippe G Schyns
    University of Glasgow, UK
Journal of Vision October 2003, Vol.3, 4. doi:10.1167/3.9.4
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      Emre Özgen, Paul T Sowden, Philippe G Schyns; I WILL use the channel I want: flexible spatial scale processing. Journal of Vision 2003;3(9):4. doi: 10.1167/3.9.4.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Spatial scale processing of natural stimuli (e.g. faces, scenes) can be flexible depending on type of categorization task and prior experience (Gosselin & Schyns, 2001, V. Res., 41, 2261–2271). We argue that attentional modulation of spatial frequency (SF) channels in early vision can account for such flexibility (Sowden, Özgen & Schyns, 2002, J. Vis., 2, 283a). Last year we reported evidence (Özgen, Sowden & Schyns, 2002, J. Vis., 2, 202a) suggesting that such early mechanisms may indeed be involved: we sensitised observers bottom-up to scenes with different SF content at separate retinal locations. Perception of hybrid images (those that contain both a low-pass and a high-pass scene of different categories) was orthogonal at different retinal locations.

Here we explored whether a top-down attentional process could also drive flexible scale use. In a sensitisation stage observers were required to categorise (highway or city) briefly presented low and high-pass filtered scenes that were combined with high and low-pass noise respectively. Prior to each stimulus a symbolic auditory cue (the words “coarse” and “fine”), expected to act top-down, signalled the SF bandwidth that would contain the scene on the next trial. In a subsequent test stage, unknown to observers, we interleaved hybrid images and continued cueing observers to expect a scene at one or the other scale. Orthogonal perceptions of hybrid images depending on the cues suggest that a top-down attentional process can also result in the flexible processing of spatial scale. Such evidence indicates that in contrast to the stimulus-determined attention to a single narrow-band SF channel reported for some tasks (cf. Majaj, Pelli, Kurshan & Palomares, 2002, Vis. Res., 42, 1165–1184) when explicit top-down cues are provided endogenous switching between channels is possible.

Özgen, E., Sowden, P. T., Schyns, P. G.(2003). I WILL use the channel I want: flexible spatial scale processing [Abstract]. Journal of Vision, 3( 9): 4, 4a, http://journalofvision.org/3/9/4/, doi:10.1167/3.9.4. [CrossRef]
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