Fitt's law Flashcards
the Fitt’s law theory
- hypothesis: if the subject works as fast as possible, their time for the task will be proportional to the amount of information demanded by the task conditions
- the amount of info demanded by a task depends on:
1. Speed
2. Amplitude
3. Width
the experiments
- Reciprocal tapping task
- Disc transfer
- Pin transfer
reciprocal tapping task
- subject must tap metal plates with a stylus, the distance between the plates and the width of the plate varies between trials
results: - small amount of error in this task, show the subjects adjusted their speed in order to more accurate on the task
- errors increased according to the more difficult task conditions, with the most errors occurring on the W=.25 A=16in
disk transfer task
-participants used their fingers to move the washers from one pin to the next as quickly as possible
results:
-found that time increases as the difficultly of the conditions increased
pin transfer task
- particpnats transferred 8 pins from on set of holes to another
- the diameter (amplitude) of pins and the distance of the holes from each other varied
- similar results from this task to the other experiments
applications
-ergonomics
-factory production
-NASA
-driving a car
-iphone, computer software, touch screens
sport/ kin related applications include:
-sports
-rehab perspective: physio exercises and prosthetic limb controllers
trunk coordination measurements
- 14 healthy adults did two series of 24 tasks involving trunk flexion-extension while sitting on a specially designed chair
- used fixed positions of focus on the wall, to create fixed variables ex) don’t move for 1 second
- researchers found linear relationships between the index of difficulty and the movement times pf the participants
restricted display field of view
- a study was done to prove the inadequacy of Fitt’s law when considering the field of view
- 10 subjects participants in discrete clicking tasks where they were asked to replicate a dot on the screen, as well as a task involving copying the movement of the dot after clicking it
- the experimenters tested the subjects at various distances to change the subject field of view
- technology development
aiming task with moving target
- 16 participants were asked to aim at two target widths with a joystick
- results showed that there was a negative effect on performance with target velocity was increased or target width was decreased
Fitt’s law in misrepresentation in Paralympic sport
- 10 participants were asked to perform Fitts tapping task with their index finger of dominant hand
- the purpose of this study was to try to catch people who were in the Paralympics who should not have been. They exaggerated their impairment severity to compete
- they were able to identify if people were performing the task sab-maximally as opposed to with maximum voluntary effort
woodworth
initial adjustment stage: time when you propel your limb to a target
current control phase: about the feedback we get as we are moving
-considered to be the one who described the relationship between speed and accuracy, Fitts then took that another step
-since the publication, there have been no study to prove it wrong
-index of difficultly: holds true for 1 and 2 dimensional. 3 dimensional doesn’t always hold true
-holds true in outer space and under water
-3 experiments included: transfer task, pegs, original tapping task
what was the activity for Fitt’s law
poker chips and target
Trial 1: speed only
Trial 2: Accuracy only
Trial 3: Speed and accuracy
index of difficultly doesn’t take into account
Weight of stylist
Energy to change directors
Time is not directly considered
width and amplitude
w: different size of actual targets
a: distance between set of targets
