Reference no: EM133195058
1. Experimenters wanted to examine people’s thresholds for discriminating weights (i.e., the smallest amount by which two weights can differ in order for participants to perceive them as different). They chose an object that weighted 100g as the reference/standard weight, and objects with weights ranging from 10g to 250g with a step size of 10g as test/ comparison weights. They measured participant’s discriminability using the method of constant stimuli.
(a) Describe the method of constant stimuli and the procedure of the experiment.
(b) Explain how you would compute the difference threshold (i.e., the just-noticeable difference).
(b) The experimenters are also interested in testing whether Weber’s law can be used to describe the JNDs for weights. Explain Weber’s law and design an experiment to test this research question.
2. Describe the differences between rod and cone photoreceptors in terms of the following aspects:
(a) Their anatomical distribution in the retina.
(b) The way they are connected with bipolar cells (convergence vs. divergence), their spatial acuity and light sensitivity.
(c) Under which lighting condition do they function better and why?
3. The amount of light entering our eyes can change drastically. For example, when we leave a dimly lit room to the outdoors with bright sunlight, the number of photons of light entering our eyes might be increased by a factor of several billion. List all the strategies our visual system uses to adjust changes in illumination and explain them with details.
4. Describe the visual pathway from the retina to primary visual cortex.
(a) Objects in the left visual field form an image on [nasal / temporal] ____ retina of the left eye and [nasal / temporal] ____ retina of the right eye; objects in the right visual field form an image on [nasal / temporal] ____ retina of the left eye and [nasal / temporal] ____ retina of the right eye.
(b) Describe the difference between optic nerve and optic tract. What will happen if there is damage in the left optic nerve? What will happen if there is damage in the right optic tract?
(c) The left optic tract goes to the [left / right / both left and right] ____ LGN, which processes information from [left / right / both left and right] ____ visual field; the right optic tract goes to the [left / right / both left and right] ____ LGN, which processes information from [left / right / both left and right] ____ visual field.
(d) LGN has a layered structure. Describe each layer in terms of the source of inputs (i.e., from the eye of the same side or opposite side), the characteristics of cells in that layer, and which pathway it goes beyond the primary visual cortex.
(e) Explain why objects that we fixate at are seen with more details compared to objects that fall in peripheral visual field.
(f) Summarize the characteristics of the receptive field of retinal ganglion cells, cells in LGN, and cells in primary visual cortex.
5. In 1958, Hubel and Wiesel found that neurons in V1 responded best to orientations.
(a) What’s the possible neural circuit that makes this receptive field possible given that neurons in LGN have a center-surround receptive field?
(b) What did they find when they put an electrode perpendicular to the surface of V1? Did neurons have the same orientation turning? Did the receptive field change?
(c) What did they find when they put an electrode parallel to the surface of V1? Explain what location column is.
(d) Explain what hypercolumns are.