sample midterm 3 2009 key

sample midterm 3 2009 key - YOUR NAME_ Student ID#_ MIDTERM...

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YOUR NAME__________________________ Student ID#_________________ 1 NPB 100 MIDTERM 3 SPRING, 2009 Your signature____ KEY __________________ Please check this box if you do not want your exam returned in the bins in the hallway… Question Score Total 1 15 2 9 3 8 4 23 5 12 6 10 7 23 TOTAL 100
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Student ID#_________________ 2 Question 1 (15 points) In class you saw the Hermann Grid illusion shown below on the left . When you looked at the black squares separated by white spaces you saw illusory dark spots at the white intersections. 1a. (5 points) Using center-surround OFF-center receptive fields, illustrate on the figure below on the right how OFF-center receptive fields can cause this illusion. Points: 3 points for drawing the two receptive fields of the correct size at the correct location. 2 points for drawing the + and – symbols correctly. 1b. (10 points) Briefly explain your answer. Both receptive fields have their centers completely in the white (light) region (2 points). Since we are using OFF-center cells, both cells have equal inhibition from their centers (1point). The cell at the intersection has more of its surround in the light (2 points). Therefore it is getting more excitation from the surround region than the other cell (1 point). Since both cells get equal inhibition, and the cell at the intersection gets more excitation, the cell at the intersection will fire more action potentials (2 points). An OFF-center cell firing more action potentials tells the brain that it is darker at the intersection, therefore we see the dark illusory spot (2 points). GO ON TO THE NEXT PAGE!
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This note was uploaded on 09/08/2010 for the course NPB NPB 100 taught by Professor Campbell during the Spring '10 term at UC Davis.

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sample midterm 3 2009 key - YOUR NAME_ Student ID#_ MIDTERM...

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