Required pracitcal - Reaction Time Flashcards
Describe how to measure a person’s reaction time
The practical requires two people to work together
Person 2 will measure the reaction time of person 1
Person 1 sits on a stool with good upright posture
Person 1 then places the forearm of their dominant arm across the table with their hand overhanging the edge
Person 2 holds a ruler vertically
The 0cm mark should be placed between person 1’s thumb and first finger
Person 2 then tells person 1 to prepare to catch the ruler
Person 2 now drops the ruler a a random time
Person 1 has to catch the ruler with their thumb and first finger as quickly as possible when it drops
Person 2 now records the measurement on the ruler that is level with the top of person 1’s thumb
At this point, person 1 has a short rest
The test is then repeated several times and a mean is calculated
Reaction time is measured/indicated by the number on the ruler where it is caught - the further down it is caught (the higher the number), the slower the reaction time
OR
We can convert our results to a reaction time, to do this, we use a conversion table.
At the end the two people switch places with person 1 testing the reaction time of person 2.
This allows us to compare/see whether the two people have different reaction times
independent variable of reaction time experiment
The independent variable is the person having their reaction time tested
dependent variable of reaction time experiment
reaction time
control variable of reaction time experiment
The starting distance between the thumb an the first finger should be kept constant
Always measure the ruler at the top of the thumb
Keep the conditions in the room the same e.g. the lighting and the level of background noise
The same person to catch the ruler each time
The person catching the ruler, should always use the same hand to catch the ruler
The ruler should be dropped from the same high
Ensure that the person being tested has not had any caffeine (or anything else that may affect their reaction time) before the start of the experiment
Describe the effect of allowing any of the control variables to change in the reaction time experiment
If we allow any of the control variables to change, this could affect our dependent variable (the reaction time)
Also for any values we measure, we cannot be sure that these values are as a result of the independent variable alone - and not any other external factors
Other independent variables that could be investigated reaction time experiment
We could investigate the effect of practice
- One person would catch the ruler a large number of times. We would then look to see if the reaction time changes depending on the number of tries
We might expect that the reaction time would become shorter, the more the person practiced
Investigate whether the reaction time depends on the hand catching the ruler
In this case we would carry out the test with the dominant hand, and then with the non-dominant hand of the same person
Because the dominant hand is the hand we use most often, we might expect that the reaction time is shorter with the dominant hand compared to the non-dominant hand
We could investigate whether certain chemicals affect the reaction time of an individual e.g. caffeine
To do this, the person drinks a measured amount of cola half an hour before the experiment
Then compare this reaction time with their normal reaction time
–> problem: there could be other chemicals in the cola which is affecting the reaction time. To check that, we would also have to carry out the test using a caffeine-free cola - and compare this reaction time with their normal reaction time
Because we are giving the person something to drink, we need to be certain that it is safe
Check that they have no medical issue which might be affected by caffeine, e.g. an allergy or a heart condition
Too much caffeine can cause unpleasant side effects so the person being tested should avoid drinking any more caffeine for the rest of the day after the experiment is completed
We need to carry out the test in a lab where hazardous chemicals are not normally used
alternative: computer is better - gives more precise measurement/reaction time - because the remove the possibility of human error from the measurement
Using a computer can also remove the possibility that the person can predict when to respond - using the ruler test, the catcher may learn to anticipate the drop by reading the tester’s body language
How computer could be used. e.g. the person being tested has to click the mouse (or press a key) as soon as they see a stimulus on the screen e.g. a box change colour
ensure this is random times this occurs - to prevent the person being tested being able to predict and anticipate when the next stimulus will appear - this can give more realistic and accurate reaction time - which we can be sure is caused solely by the person
