Dr. Northmore's Sections

Here is a sample test to show you the format.  The material that will be
covered in the upcoming test on Wednesday 29 September may be somewhat
different.  Watch this space for details.							

       PSYC 310                  MIDTERM EXAM I                  SPRING 1999

Part A.  Short Answers  (worth a total of 50%)

1. Matching: write in parentheses the letters of matching descriptors.
(  ) Bipolar cells		A.	Simple cells of Hubel & Wiesel
(  ) Visual pigment		B.	Eye movement controller
(  ) Prosopagnosia		C.	Vision without awareness
(  ) Fovea			D.	Color sensitive cells
(  ) Blindsight	 		E.	Face recognition problem
(  ) Superior colliculus		F.	Where optic nerves cross
(  ) P-cells			G.	Lengthening near point 
(  ) Optic chiasm		H.	Opsin + retinal
(  ) Presbyopia			I.	Connect receptors with ganglion cells
(  ) Orientation selective	J.	Cone rich area

2. What are the eye's two focusing elements? _________________  and ____________________.
In a normal eye without accommodation a near object is brought into focus
	(a) in front of,    (b) on,      (c) behind the retina.  __________________.
A pinhole pupil ameliorates (a) myopia, (b) hyperopia, (c) astigmatism, (d) depth of focus, (e) a through d. ________________.

3. Number  the following structures in order from peripheral (1) to central (5):
Chiasm,	Striate cortex, 		Lateral geniculate nucleus,        Retina,      Inferotemporal cortex.
____		_____			_____				 _____		______


4.  What is the duplicity theory of vision? (<25 words )



5. Draw two curves representing the spectral sensitivity of (a) rod vision, and (b) cone vision.
Indicate which is the RED end of the spectrum and which is the BLUE.

6.  Receptive fields of LGN cells resemble most those of (a) retinal ganglion cells, (b) cortical simple cells, (c) V4 cells    ____________

What is thought to be the main function of the LGN? 





7.  Stevens' power law relates magnitude of perception (P) to stimulus intensity (S).  Give an equation representing it:  ____________ .
Fill in the table explaining the Power law relationships for the three kinds of stimulus using the following terms:
Expansive,  Compressive,  Linear,  Equal to one (=1),  Less than one (<1),  Greater than one (>1).

Stimulus
Relationship
Exponent
Brightness


Electric shock


Line length



8.  In what units do we measure spatial frequency ?  ________________.
In a photograph of a face, which features would present high spatial frequencies?  _____________
And which low spatial frequencies? ____________________.
In theory, the face could by synthesized by summing the appropriate sine wave gratings.
Whose theory? ___________________.

9.  Half of the following terms belong with the dorsal stream, half with the ventral.
  Indicate which with D or V below each:
M-cell     Color     Form     Movement   "Where"   P-cell   Temporal      MT     Parietal      V4
_____     _____     ____     _________   ______    ____   ________      ____     ______    ____

Part B. 	Answer ONE of the following with an essay. (worth 50%)
* Before writing, spend a few minutes analyzing the question and jot down thoughts, topics to include etc. on this question sheet.
* Put your name on all sheets

10.  Explain how retinal mechanisms could account for illusions of lightness, such as simultaneous lightness contrast and Mach bands.  When do these explanations fail?

11. Explain what is meant by the cortical magnification factor. How is it achieved and why is it important?

12.  Give an account of what is currently known about the "Ventral visual stream" that allows us to recognize complex objects.

13.  What is the binding problem?  Explain how Engel et al. think it can be solved by spike synchronization, and give their evidence.
??