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Lecture 3

PSY 3108 Lecture Notes - Lecture 3: Microsoft Excel, Power Law, Stopwatch

9 pages90 viewsSpring 2018

Department
Psychology
Course Code
PSY 3108
Professor
Charles Collin
Lecture
3

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Chapter 3 Lab, Page 1 of 9
LAB 2 (CHAPTER 3): SOMATOSENSORY PERCEPTION
(graded out of 50, worth 5% of final grade)
This lab consists of three parts. These exercises will probably be easiest to do at
home although the lab is available to you if you wish. You will need someone to act
as an observer (participant) for all three parts. This can be someone from class, a
friend, sibling, etc. If it's a classmate, then do each part twice, switching roles
between observer and experimenter.
Equipment Required
Part 1:
- A compass, the kind with two points. Alternatively, take a paperclip (the
regular "trombone" kind), unbend it so that it's a (relatively) straight
piece of wire, then bend it into a skinny "U shape".
- A ruler with millimeters marked.
Part 2:
- A thermometer (a kitchen thermometer or meat thermometer will do)
- A microwaveable cup full of water.
Part 3:
- 10 small common objects that can be identified by touch.
- A stopwatch or equivalent
Handing In
Hand in your lab as follows:
1. Fill out this document in the spaces provided
2. Save it as "Lab2YourNameStudent#.docx"
(e.g., Lab2CharlesCollin123456.docx). It's okay if it's .doc format.
3. Send it via email to the following address: [email protected]
4. Use the subject line: PSY3108X Lab2, YourName StudentNumber
(e.g., PSY3108A Lab2, Charles Collin 123456)
Failure to follow these instructions properly will lead to a 10% mark deduction, so
be careful!
If, for some reason, you cannot submit your lab electronically, then you may submit
a paper copy instead.
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Chapter 3 Lab, Page 2 of 9
Part 1: Measuring Two-Point Threshold by Method of Limits (20 marks)
In this part of the lab, you will measure three absolute thresholds using the classic
Method of Limits. In preparation, you should re-read the section in Chapter 1 on
psychophysical methods and thresholds, focusing especially on the Method of Limits,
as well as the section in Chapter 3 on measuring two-point thresholds.
Method:
1. Experimenter and observer should sit at a table across from one another in a
quiet area without distractions.
Experimenter: Adjust the compass so that its points are 10 mm apart.
Observer: Lay your right arm on the table, palm up, fingers outstretched. If
wearing long sleeves, roll the right one up to the elbow. Close your eyes.
2. Experimenter: You'll be testing the participant's ability to distinguish
between one-point and two-point skin contact at a variety of distances. On
each trial, flip a coin. If it is heads, then do two-points, then one. If tails, do
one point, then two. That is, if you got heads, then touch both points of the
compass to the observer's skin first, then touch just one point. In all cases,
apply only gentle pressure; just enough to slightly dent the skin. When doing
two-points, make sure both points touch at the same time. Ask the observer if
she feels two points on the first touch or the second. This is called a temporal
2AFC task. Record whether her answer was correct (Y or N) in the grid at the
end of this section.
Observer: Do your best to report whether you felt two points on the first
touch or the second. If you're unsure, guess.
3. Experimenter: Adjust the distance between the two points to 8 mm and
repeat the procedure, asking whether the observer feels two points on the
first touch or the second. Continue this way, reducing the distance by 2 mm
each time until the observer makes a mistake. This completes the first run,
which is a descending run.
4. Next, complete an ascending run. That is, start with the points of the compass
2 mm apart (or as close as they can go), and go up by 2 mm increments until
the observer reports feeling two points separately.
5. Complete a total of two descending runs and two ascending runs. Calculate
the thresholds for each run, and the overall threshold for the four runs.
6. Repeat the entire above procedurefour runs, alternating between
ascending and descendingfor the palm of the hand. Touch the points right
in the centre of the palm. However, this time start descending runs at 20 mm
and go by steps of 4 mm.
7. Repeat the entire procedurefour runs, alternating between ascending and
descendingfor the forearm. Touch the points about 5 cm down from the
inside of the elbow. However, this time start descending runs at 60 mm and
go by steps of 10 mm.
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Chapter 3 Lab, Page 3 of 9
NOTE: If the maximum values given above (10 mm for finger, 20 for palm, 60 for
forearm) are not sufficient for the observer to feel two points, then go beyond this,
trying larger increments, until she is able to feel two points.
Results: Enter subject responses in the following grids. Using the procedure we
went over in class, calculate the threshold for each run and the overall threshold.
FINGERTIP
Run 1
Run 2
Run 3
Run 4
2-point Dist.
Threshold:
Average Threshold = ___________
PALM
Run 1
Run 2
Run 3
Run 4
2-point Dist.
Threshold:
Average Threshold = ___________
FOREARM
Run 1
Run 2
Run 3
Run 4
2-point Dist.
Threshold:
Average Threshold = ___________
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