human movement and fitts law Flashcards
how many possible combinations
16
factor of distance
the movement time increases with the distance
factor of width
the wider the target the faster you reach it
inverse effect
halving the width means the target is twice as hard to get to
direct effect
increasing the size of the target and decreasing the distance makes it easier and faster to hit
what is fitts law
a model of human performance
distance
amplitude of movement
width
tolerance for landing on the target
how do you calculate the index of difficulty
ID = log2 (D/W + 1)
what does the index of difficulty tell us
the same distance with a larger target or the same size with a closer distance gives a smaller index of difficulty
what is the formula for fitts law
MT = a + b * ID
what is the generalisation formula
MT = a + b *ID = a + b * log2 (D/W + 1)
speed-accuracy tradeoff
were more accurate when we move slowly and we can move faster when we dont need to be accurate
motor space
the physical area you move in to interact with a target
display space
the are of the screen where the target is shown
what is the factor of device
the speed and accuracy depend on the input; the movement of the user sensed in motor space, the input devices, the mapping of the input from motor space to display space
control-display gain
speed of the device on motor space
c-d gain > 1
less movement of the input device for faster display movements
good for big distances
c-d gain < 1
more movement of the device in motor space for smaller movement on the screen
fine motoring
throughput
how much information is transferred to a computer
snr; signal to noise ratio
how much useful signal gets through compared to unwanted interference; noise
when does throughput increase
when we complete more difficult tasks within a given time
when we need less time for a task of given difficulty
formula for throughput
TD = ID/MT
