Marco Turi
PhD Student in Cognitive Science, University of Florence
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Contacts
Research laboratories
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Current research and interests
- Numerosity perception
- Multi-sensory perception
- Motion
- Crowding
- Attention
Publications
2011
Burr, D. C., Anobile, G. & Turi, M. (2011). Adaptation Affects Both High and Low (Subitized) Numbers Under Conditions of High Attentional Load,Seeing and Perceiving, (24), 141-150. PDF
It has recently been reported that, like most sensory systems, numerosity is subject to adaptation. However, the effect seemed to be limited to numerosity estimation outside the subitizing range. In this study we show that low numbers, clearly in the subitizing range, are adaptable under conditions of high attentional load. These results support the idea that numerosity is detected by a perceptual mechanism that operates over the entire range of numbers, supplemented by an attention-based system for small numbers (subitizing).
2010
Burr, D. C., Turi, M. & Anobile, G. (2010). Subitizing but not estimation of numerosity requires attentional resources,J Vis, 6 (10), 20. PDF
The numerosity of small numbers of objects, up to about four, can be rapidly appraised without error, a phenomenon known as subitizing. Larger numbers can either be counted, accurately but slowly, or estimated, rapidly but with errors. There has been some debate as to whether subitizing uses the same or different mechanisms than those of higher numerical ranges and whether it requires attentional resources. We measure subjects' accuracy and precision in making rapid judgments of numerosity for target numbers spanning the subitizing and estimation ranges while manipulating the attentional load, both with a spatial dual task and the "attentional blink" dual-task paradigm. The results of both attentional manipulations were similar. In the high-load attentional condition, Weber fractions were similar in the subitizing (2-4) and estimation (5-7) ranges (10-15%). In the low-load and single-task condition, Weber fractions substantially improved in the subitizing range, becoming nearly error-free, while the estimation range was relatively unaffected. The results show that the mechanisms operating over the subitizing and estimation ranges are not identical. We suggest that pre-attentive estimation mechanisms works at all ranges, but in the subitizing range, attentive mechanisms also come into play.
2009
2008
2007
2006
Conferences
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