In two experiments, we explored the utility of
using event-related brain potentials (ERPs) evoked during
picture recognition to examine the cognitive and neural
processes underlying primacy and recency effects. Each
experiment consisted of 210 trials in which a recognition
probe followed a 12-picture sequence (105 match and 105
nonmatch trials). The 105 match-probe trials consisted
of 35 trials in which the probe matched a prime memory
set item (Positions 1–3), 35 in which the probe matched
a middle memory set item (Positions 6–8), and 35
in which the probe matched a recent memory set item (Positions
10–12). Behavioral results revealed recency but not
primacy effects in both experiments. Recent probes, compared
with prime and middle probes, evoked ERPs that were more
positive from approximately 300 to 400 ms; this enhanced
positivity occurred in a positive component peaking around
315 ms and a negative component peaking around 365 ms.
These findings fit more closely with the notion of short-term
memory as an activation of elements in long-term memory
than as a distinct memory store (or stores) separate from
long-term memory.