Week 9. Is the magnitude estimation system conscious?
– No reason to estimate if we have clear consciousness about all of each items –
Hunjae Lee (VCC Lab)
Knowing the approximation is a kind of marvelous ability of human or primates. Without a measuring cup, we can estimate how much ingredients need to be added when we cook. We can guess how many people are standing in each waiting line in front of ticket box by just a glance, and choose more fast one without counting number of people. However, estimation is merely the close answer not the precise one. If we can discriminate all of individuals and count them during very short time, there is no reason to estimate something with clear consciousness and correct answer. This suggests that our estimation system is somehow under consciousness when it process information rapidly.
Integrated magnitude system suggested by Walsh (2003) shows various research data including behavioral, neurophysiologic, and brain imaging evidences of common cortical metrics, and most of them are focused on estimation processing rather than counting. Then, does it mean that only the magnitude estimation is integrated? One possible answer is two distinct core system proposed by Feigenson et al (2004). They distinguish precise representation of number and approximation of it, in other words, absolute figure versus relative ratio. Actually there is a evidence of double dissociation between counting by temporal lobe and dissociation by parietal lobe (Lemer et al, 2003).
With those studies above, my answer is based on well-known classical two pathway of visual system, dorsal and ventral stream. First, we can estimate magnitude with dorsal pathway that is faster, and then we recognize it with ventral pathway, now successfully achieve visual awareness. And in this process we need attention for sure to unite two pathways. (What is the most adequate citation of this, Sir?) This can be why we couldn’t be conscious with magnitude estimate system. Because of limitation of attention capacity, we should distribute attention over numerous objects to process whole of them within a short time.
Additionally, beyond the question of this week, I raise a questions about texture density (Durgin, 1995, 208) and numerosity of objects (Burr et al, 2008a, 2008b), “From what extent do we say the visual scene as objects rather than texture?” Easily thinking, it would be different as the size of dot increases. (They use too small dots. e.g. 0.2° in Durgin, 1995) And does magnitude estimation system be overloaded with different modal of magnitude such as number and size? I am curious and nowadays I look forward data of my experiments tell us something interesting besides mean size calculation.
Feigenson, L., S. Dehaene, et al. (2004). Core systems of number. Trends in Cognitive Sciences 8(7): 307-14.
Walsh, V. (2003). A theory of magnitude: common cortical metrics of time, space and quantity. Trends in Cognitive Sciences 7(11): 483-8.
Burr, D. and J. Ross (2008a). A visual sense of number. Current Biology 18(6): 425-8.
Durgin, F. H. (1995). Texture density adaptation and the perceived numerosity and distribution of texture. Journal of Experimental Psychology: Human Perception and Performance 21(1): 149-69.
Lemer, C., Dehaene, S., Spelke, E., & Cohen, L. (2003). Approximate quantities and exact number words: dissociable systems. Neuropsychologia, 41, 1942–1958.
Durgin, F. (2008). Texture density adaptation and visual number. Current Biology. 18(18), R855.R856.
Burr, D. & Ross, J. (2008b). Response: Visual number. Current Biology. 18(18), R857.R858.