Nervous System Lab Problem: Is there a measurable difference between the rate at which one can process sensory information obtained visually, orally, and tactually? Procedure: Visual 1. Obtain a meter stick. 2. Hold a meter stick vertically with the “0 cm” end down and approximately at waist height. (The 100 cm end would be high in the air) 3. Have your partner hold her writing hand with her thumb and forefinger held even with the bottom (0 cm end) of the meter stick with one digit on each side of it as if they were going to squeeze it. 4. Prepare to drop the meter stick. 5. Drop the meter stick and have your partner try to catch it as quickly as she can. Don’t give any verbal warnings of when you will drop it. Record the distance the meter stick fell before your partner grabbed it by looking at the part of the meter stick their fingers grabbed. 6. Repeat this procedure until you have recorded ten data points. Then, switch positions and repeat with your partner. Auditory 1. Repeat the procedure above, but this time have the “catcher” close his or her eyes. The dropper indicates when the meter stick is dropped by saying “Now”. It is very important that the dropper says, “Now” exactly when the meter stick is dropped. 2. Repeat the exercise for the other partner. Tactile 1. This time, the catcher closes his or her eyes again, and the dropper indicates the meter stick is being dropped by tapping the catcher on the shoulder. 2. Repeat the exercise for the other partner. Data Visual Data Person 1 Person 2 Auditory Data Person 1 Person 2 Tactile Data Person 1 Person 2 Analysis of Data: The big question is how to make sense of all this data. For this, we will need to use a statistical tool known as a two-sample t test. The two-sample t test allows you to determine if two sets of data are statistically different. We can expect to get different means for each method, but can we say that the difference in mean is a meaningful, valuable piece of data, or is simply the result of chance (sampling error, the whole if-you-flip-a-coin-ten-times thing)? Because this is a TWO-sample t test, we will only be able to compare two samples at a time. Thus, we will need to repeat our calculations three times: 1) compare visual and auditory, 2) compare visual and tactile, and 3) compare auditory and tactile. SHOW ALL CALCULATIONS NEATLY ON A SEPARATE SHEET OF PAPER! 1. Calculate the mean of each category. USE YOUR CALCULATOR to do this. Record in the table below. 2. Write the null hypothesis and alternative hypothesis in the data table below for each of the three experiments. 3. Calculate the degrees of freedom for visual/auditory using the following formula: Degrees of freedom = n1 + n2 – 2 4. Calculate and record the difference between the means. 5. Use the instructions at the end of the lab to enter your data into your calculator and calculate the p value. 6. Record the data in your table below. 7. Use the p< 0.05 to accept or reject the null. 8. Repeat the entire procedure for visual and tactile, and for auditory and tactile. Visual Auditory Mean (x) Visual and Auditory Null hypothesis Alternative hypothesis Degrees of freedom Difference between the two means P value calculated from calculator Accept or reject null Is there a statistical difference? Is so, which is faster? Visual and Tactile Null hypothesis Alternative hypothesis Degrees of freedom Difference between the two means P value calculated from calculator Accept or reject null Is there a statistical difference? Is so, which is faster? Tactile and Auditory Null hypothesis Alternative hypothesis Degrees of freedom Difference between the two means P value calculated from calculator Accept or reject null Is there a statistical difference? Is so, which is faster? Write 2-3 sentence conclusion on the results obtained in this experiment.: Tactile T test instructions for TI 83+ 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. Press stat Edit should be highlighted, ENTER In the column L1 enter a data point and ENTER Continue to enter all 10 data points In column L2 enter a data point and ENTER Continue to enter all 10 data points Press STAT Tab over to TESTS at the top of screen Move down to #4 2 sample T-Test Enter It comes up Data Move the arrow down to u1 =/ u2 Enter Move to pooled data YES Enter Move down to calculate Enter _ x is given (mean). Record it p value is given. Record it. This is the chance that the differences between the group is just due to randomness. Therefore 1- p is the chance you are sure that there is a difference between the data groups. ex. P=.02 means 98% chance there is a difference. Repeat this process or have your partners do it for the other 2 comparisons Visual to auditory Visual to tactile Auditory to tactile Determine which ones if any are significant in their impact on reaction time.