Great article for methods:

http://www.journalofvision.org/content/13/1/24

Visual angle of letters:

Boots CRT monitor is 36.5 cm wide. Comfortable sitting distance for AC is 50cm exactly, so use this as viewing distance. Currently, PTB whole-screen window is 1024 pixels wide, so 20.48 px/cm.

NOTE: this size is for use with the boots PC and monitor only! This pixel size is tiny on diego's monitor.

Strasburger & Malania used 4 deg. eccentricity targets

4 deg. at 50cm on the boots CRT monitor: 3.49cm = 71.47px ~ 71 px.

.5 deg at 50cm on boots CRT: .44cm = 9.01 ~ 9 px.

Can use stimulus width as the distance between flankers.

Plan: scale these numbers up, but keep the ratios.

First try: if boots CRT is 1024 px wide, can go up to almost 512 px eccentricity, 512/71 ~ 7. So let's scale up by 5 to be safe:

Place target at 71*5 ~ 350 px away from fixation cross (which should be at the center of the monitor) Make targets 9*5 = 45 px tall and 45 pixels apart.