coordinates into cm

loes0788

Hi,
For my experiment I have a sketchpad with 2 images on opposite sides (left and right). I need to make sure that both images are separated 14 cm from the center of the sketchpad. Is it possible to put the distances in cm instead of as coordinates?

sebastiaan

Hi Loes,

You cannot directly specify a distance in cm, but it's not so difficult to calculate. First, simply measure how wide your monitor is. Let's say it's 50 cm. Then take the horizontal resolution (width) of the display. Let's say it's 1920 px. You then have 1920 / 50 = 38.4 pixel per cm. So a distance of 14 cm would be 38.4 × 14 ~= 538 px.

Expressing stimulus sizes in cm is a bit unusual though. Most people do this in degrees of visual angle, as described here:

• http://osdoc.cogsci.nl/3.2/visualangle/

Cheers!
Sebastiaan