Participants were instructed to decide as fast as possible whether the probe belonged to the memory-set (target) or not (non-target).
On half of the trials, the memory probe's identity matched that of the memory set stimulus.
Each digit occurred equally often in the memory set and was equally often in the memory probe.
The memory probe appeared next, comprising a single square presented in one of the occupied memory set positions.
The memory probe was displayed for 3000 ms, during which time participants made their memory task response.
When the memory probe was of the same category as the memory item, each of the four exemplars had an equal probability of being the probe.
After a 500-ms ISI, a single object (the memory probe) was centrally presented.
A memory probe was then presented for 3 s (or until a response was made).
The memory probe digit was a match on 50% of trials selected at random.
We further mapped these probes to probe sets and there were 1,062 probe sets which include at least 3 probes belonging to the intersection.
