d). Draw the following neural circuits (using the notation taught in class) and then say what would happen if they were stimulated as specified.

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1 1. The neuropsychology of perception. a). Describe the process in which a neural impulse travel down one axon, making sure to specify chemical substances involved and how that affects the charge within the cell at each stage. Use a graph to show how the membrane potential changes as a function during the different stages of the process. Answer: neural impulses, or action potentials travel down an axon when stimulated enough and there is a transfer of ions; the neuron goes up to 40 positive millivolts and let in sodium ions and boots out potassium ions, it will then go down to below 70 negative millivolts which is the recovery phase during which the sodium ions are booted out and the potassium ions are taken back in; it will then return to its resting potential of -70 millivolts b). What are neurotransmitters? Describe the difference between neurotransmitters that have excitatory and inhibitory effects, using examples of neurotransmitters of each type to clarify your description. Answer: neurotransmitters are different types of chemicals that travel through neurons to send information; excitatory neurotransmitters increase the probability that the receiver will have an action potential (they increase the positivity, or in other words depolarize), acetylcholine, curare and glutamate are exctitatory. Inhibitory neurotransmitters reduce the probability that a neuron will have an action potential; gaba and serotonin are examples c). What does it mean to say that cells have a rate of spontaneous activity? Why is this important to understanding the way that neurons send messages and communicate? Answer: spontaneous activity means that neurotransmitters are released through the synaptic gap to other neurons (action potential) without any stimulation; this is important to know because a neuron that is stimulated is already firing off action potentials from its spontaneous activity and neurons will be affected differently depending on whether it is being stimulated by an excitatory or inhibitory neurotransmitter d). Draw the following neural circuits (using the notation taught in class) and then say what would happen if they were stimulated as specified. i). A simple excitatory linear circuit between neurons A and B and C. What would happen to the activity of B if A were stimulated? A B C Answer: A would receive an action potential and since it is an excitatory neuron, B would therefore be stimulated ii). A circuit that shows convergence between neurons that send excitatory neurotransmitters. eurons A, B, and C each lead into neuron D (and no other neuron).

2 What would happen to the activity of neuron C if A and B were stimulated? Answer: othing would happen to C because they are attached to neuron D and therefore wouldn t stimulate eachother, only neuron D iii). A circuit that shows convergence between neurons that have excitatory and inhibitory neurotransmitters. eurons A and B each lead into neuron C (and no other neuron). What would happen to the activity of neuron C if neurons A and B were stimulated at the same time (and to an equal extent). Assume that all axons are the same length and there is no difference in the effectiveness of neurotransmitters. Answer: Since neurons A and B are an excitatory and inhibitory neurotransmitter, if both were stimulating neuron C to an equal extent, they would cancel each other out and neuron C would receive no stimulation. 2. Psychophysics I. a). Describe the *3* major psychological methods for measuring the absolute threshold, making use of the example of your own creation to illustrate how each would work. Answer: method of limits involves the experimenter presenting the stimulus in ascending order and then descending order, after which the two results are averaged out to give you the participants absolute threshold; the method of adjustments involves the participant manually adjusting the stimulus intensity until they cant just barely detect it and then that is their absolute threshold; the constant stimuli method involves the experimenter presenting 5-9 stimuli with different intensities in random order many times and the absolute threshold is determined by which intensity is detected 50% of the time b). What is a difference threshold and how is it measured? What is a JD? (Use an example of your own creation to clarify these ideas.) Answer: the difference limens is the smallest difference detectable between two stimuli, it is measured by the method of limits, method of adjustment or method of constants; the JD is just noticeable difference c). Describe Weber's Law using an example of your own creation to clarify your ideas. Answer: Webers Law: K = JD/S; K is a constant called the Weber fraction, S is the value of the standard stimulus and JD is the just noticeable difference or difference threshold (or differenze limenz) d) A researcher was interested in measuring the faintest sound that people could detect. Sound intensities range from 1 to 10 in this study (with 10 being the most intense or loudest sound). What is the absolute threshold in this study? Y= subject says that they sense it. = subject says no they do not sense it.

3 Intensity Trial 1 Trial 2 Trial 3 Trial 4 23 Y Y Y Y 22 Y Y Y Y 21 Y Y Y Y 20 Y Y Y 19 Y Answer: Trial 1 is 18.5, Trial 2 is 20.5, Trial 3 is 19.5 and Trial 4 is 19.5; ( )/4=19.5 THEREFORE the absolute threshold for the participant is 19.5 i. What type of study is this? Answer: This is a method of limits study ii. ii. Calculate the absolute threshold in this study. (I'm looking for a numerical answer.) Answer: 19.5 iii. What is the difference between how absolute and difference thresholds are calculated in method of constants studies? Illustrate the difference using an example of your own creation involving absolute and difference taste thresholds for substance X. [The physical intensity of a tasted substance can be measured in terms of the number of mg of the substance (substance X in this case) per 1000 liters of water.] You should be getting numerical answers here, reflecting the values you have calculated from your hypothetical study

4 3. Psychophysics II. based on your graphs. You will need to be able to do this type of calculation for the exam. a. What is the difference between a signal detection study and other types of study? Answer: signal detection studies distinguishes between true sensitivity and the tendency to say yes or no; they involve a tone, or intensity, being presented half the time with nothing being presented the other half of the time b. A researcher was interested in finding out who had the most acute sense of sight. > Who has most sensitivity? How do you know? Answer: Trudy has the most sensitivity because she had 20 hits and zero misses (+20) whereas Biff had 80 hits and 70 misses (+10) A criterion is a rule for deciding when to say yes or no. Some people need more sensory evidence before they say "yes" I sense it (which means that they don't say "yes" very often). These people have a conservative criterion. Others don t take as much evidence before they say Yes, I sense it.. These people are said to have a liberal criterion. How would you know what type of criterion they had? (Hint: It's simpler than you would think...) Answer: Someone who has a lot of yes answers (and therefore a lot of hits and a lot of false alarms) would be considered liberal and someone who has a lot of no answers (and therefore a lot of misses and correct rejections) would be considered conservative c. What is the ROC curve? What does it measure (describe each axis)? How could a person be induced to develop a COSERVATIVE criterion? How could a person be induced to develop a LIBERAL criterion? Answer: a ROC curve is a receiving operating characteristics curve; it considers variables that could affect someones response other than their sensitivity: we can manipulate a persons motivation by means of payoffs, for example, by giving 100$ for hits we can encourage liberal answering but for 100$ for correct rejections we can encourage conservative answering 4. Psychophysics III. a). Your task is to measure how the perceived sweetness of a glass of lemonade varies with the amount of sugar in it. How would you go about measuring this? (Hint: You will need to be able to plot a power function from the resulting data.) b). What does the power function tell us? What is the functional significance of exponents of less than 1.0 and of more than 1.0? Use examples to clarify and illustrate your answer (i.e., if you had an exponent of less than 1.0 what would this tell you about

5 how perceived sweetness increases with sugar? What if it was more than 1.0?) Power functions: P=KSn; P is perceived magnitude, K is a constant times the stimulus intensity (S) raised to a power (n) The relationship between the intensity of a stimulus and our perception of its magnitude follow that equation; as intensity increases, perceptual magnitude increases more than intensity 5. Anomalies in vision. a). In lecture we discussed a number of things that change in your visual system as you get older. Describe *3* changes that occur with normal aging. (Hint: These are not associated with specific diseases or conditions affecting only a certain proportion of the population. Instead, these conditions will affect everyone or almost everyone as they age.) For each anomaly describe the following: i) the part of the visual system affected; ii) how vision is affected and what causes it to be affected in that way; iii) the practical consequences of this condition in terms of dayto-day life. Answer: presbyopia is when your lens grows like an onion and the tissue gets more packed and hardened and therefore doesn t bend well and you cant see things that are near as well, a convex glasses lens can help eyesight; cataracts is a lens disorder where the lens gets milky and there are problems in seeing the just noticeable differences in light perception and can be fixed through phacoemulsification; senile myosis is when your iris cant go as wide as you get older and you cant see as well in the dark b). Everyone knows someone who has some sort of visual anomaly. (It may be you!) Describe the visual problem of the person you know, how it affects their life, and then explain why it occurs in terms of what is going on with the structures of the eye. (Hint: It should not be one of the deficits discussed in parts a of this question.) Answer: accommodation is when you have to bend light rays by rounding out or flattening your lens to see things that are close or far: myopia is nearsightedness; you can have axial myopia which is when someone is born with an elongated eyeball and therefore things that are far away are out of focus but things that are close are very focused, or refractive myopia is when your lens and cornea together are too powerful; you must wear concaved glasses lens that curve inward and therefore the light rays in your vision are artificially widened or you can have excimer laser surgery which shaves off park of the cornea 6. Rod and cone vision. a). What is the difference between rods and cones in terms of their physiology (i.e., their physical makeup, location)?

6 Answer: there are more rods in our eyes than cones, rods are located in our peripheral vision and cones are in the fovea and perceive fine detail; rods contain rhodopsin and are responsible for night vision and cones have 3 kinds of photopigments that absorb red, green and blue light really well b). Describe *2* reasons that rod vision is more sensitive than cone vision. Answer: rod vision is more sensitive because they don t require much light to work and a rod receptor can be activated by the isomerization of just 1 visual pigment molecule c). What is the Purkinje effect? How does that relate to rod and cone vision? (Use a practical example of your own construction to clarify your points.) Answer: at low light levels, the tendency for the peak luminance sensitivity of the human eye to shift toward the blue end of the illumination levels; there is an initial rapid stage due to adaptation of the cone receptors and later a slower stage due to adaptation of the rod receptors; as soon as the light is extinguished, the sensitivity of both the cones and the rods begins increasing, but because our vision is controlled by the receptor system that is most sensitive, the cones determine the early part of the dark adaptation curve; the rods are increasing in their sensitivity in the dark during the cone part of the dark adaptation curve, after the cones finish off, the rods sensitivity continues to increase, then catch up to the cones and then become more sensitive and control the persons vision and the course of rod dark adaptation becomes visible in the place where the rods begin to determine the dark adaptation curve is called the rod-cone break