Table 3. Cues and distractors.

Cue Letter	Distractor Letters
C	D	E	O
D	C	O	P
E	C	F	P
F	E	P	T
L	T	Z	O
O	C	D	L
P	D	F	Z
T	F	L	Z
Z	E	L	T

The nine letters used from the Snellen set are shown paired with their three distractors. Each letter appears in the table once as a cue, and three times as a distractor. Each trial uses one of the cues and one of the three distractors associated with that cue. Distractors were selected to match cues in identification difficulty, and to form a closed, balanced set. The letter recognition paradigm involves a total of twenty seven randomly presented alternative choice combinations.