In an important first experiment to study brain region MT, Newsome and Paré (1988) trained monkeys to respond to a pattern of dots all moving in the same direction. However, they added an interesting manipulation. In some trials, all of the dots were moving in the same direction (100%), but in other conditions, only 50% or 20% of the dots were moving in sync, whereas the rest of the dots were moving randomly. As such, in these conditions, no dot, in and of itself, could determine the large-scale motion seen in the pattern, as any particular dot might just be going in the opposite direction. In essence, this experiment was looking at the physiological basis of the gestalt principle of common fate—do we see motion when a pattern of dots is moving in a particular direction, even if an individual dot is not?
In this activity, you can see these random dot patterns and try out your ability to determine overall motion with dots of different levels of overall corrlation of movement.
To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.
Below is a list of the ways that you can alter the illustration. The settings include the following:
Move: Start and stop the motion of the dots.
Degree of Correlation: Choose some present values for the overall corrlation of the dots. Selecting Choose will allow you to select any value for correlation and 100% means all dots move in the same direction.
Proportion of Dots Correlated: Choose any value of the correlation setting.
New Direction: Randmoly select a direction of motion from up, down, left, or right.
Number of Dots: Change the number of dots on the screen.
Color: Change the color of the correlated dots.
Shape: Change the shape of correlated dots. The higher the value the more these dots are circles like the rest of the dots, the lower the value the more the gestalt groupsing dots are squares.
Guess the Direction: Guess the overall direction and get feedback.
Pressing this button restores the settings to their default values.