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David Burr, Irene Togoli, Roberto Arrighi; Evidence for an abstract multi-modal sense of number. Journal of Vision 2013;13(9):618. doi: 10.1167/13.9.618.
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© ARVO (1962-2015); The Authors (2016-present)
A truly abstract number sense should be capable of encoding the numerosity of any set of discrete elements, whether events or objects, simultaneous or sequential, from any sensory modality. Recently we have shown that like other visual attributes, visual numerosity is susceptible to adaptation (Burr and Ross, 2008, Curr. Biol.). We now demonstrate that adaptation also occurs with sequentially presented items, across modalities and across formats (sequential vs simultaneous). Adapting to a series of flashes presented at 2, 4 or 8 Hz for about 40 seconds changes the perceived numerosity of visual pulses (range 2-20) presented within a temporal window of 2 seconds: adapting to 2 Hz increased perceived number by 15-20%; adapting to 8 Hz decreased perceived number by a similar amount; and 4 Hz adaptors had no effect. For adaptation to occur, the adaptor stimulus had to occupy the same spatial position as the test: they need to coincide on the screen, but not on the retina, implying spatiotopic selectivity. Similar adaptation effects were observed for auditory stimuli (adaptation to tone sequences), and also cross-modally: adapting to auditory bursts affected perceived visual numerosity and vice versa, to the same extent as intra-modal adaption. Finally we demonstrated cross-format adaptation: adapting to sequential streams of flashes reduced the perceived numerosity of spatial arrays. All these results point to the existence of a perceptual system that transcends vision and audition to encode an abstract sense of number, in space and in time. This multi-sensory, multi-dimensional mechanism is clearly separate from other perceptual systems, such as those encoding texture or density.
Meeting abstract presented at VSS 2013
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