Numerical Cognition
    I am very interested in how we comprehend numbers.  How do we understand what the symbol 7 represents? There are many fascinating phenomena associated with how people comprehend numbers.  For example, people from left-to-right writing cultures are faster identifying large numbers as even (or odd) with their right hand than they are with their left hand; and they are faster identifying small numbers as even (or odd) with their left hand than their right (a phenomenon called the SNARC effect).  The reverse is true of people from right-to-left writing cultures.  Israelis who are used to both directions show no differences between their left and right hands.   The numerical cognition phenomenon I have studied at length is called the size congruity effect.  Consider the following:

8                                2
Which digit is larger the 8 or the 2?  The answer, of course, depends upon whether you are discussing the physical size or the quantities represented by each digit.  Interestingly, people are unable to judge physical size without the quantities represented by the digits interfering with their judgment.  Typically, incongruities like the one shown above will slow people down by about 25 milliseconds (that is 25/1000ths of a second).  Of course, you might not care about 25/1000ths of a second unless you are a total geek like me.  But what is interesting is what these 25 milliseconds tells us about how people comprehend numbers.  Do people actually comprehend that the digit 8 means | | | | | | | |, that the digit 2 means | |, and that | | | | | | | | is greater than | | so quickly?  I think not (of course, I could be wrong).  Instead, I believe that people associate digits with the attributes "small" and "large" that quickly.  See my papers: Choplin and Logan (2003) and Choplin and Logan (2005).

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