its spatial and temporal characteristics as well as in its sensitivity to factors like attention. With the N400, then, these different input streams converge -- temporally, spatially and functionally. Given notable variability across stimuli in factors such as familiarity and perceptual complexity, it would seem that the time needed to settle into a final, stable state of perceptual analysis (i.e., “recognition”) must necessarily differ for different types of input (and, likely, also as a function of task and context). Indeed behavioral and other electrophysiological indices (such as the P3b) change their latency relative to the stimulus of interest in ways that are systematically related to these factors (e.g., Kutas et al 1977). Yet, such variables routinely affect the amplitude – but usually not the timing – of the N400 (see review in Federmeier & Laszlo 2009). This implies that initial access to long-term multimodal (“semantic”) memory, as indexed by the N400, occurs at different points along the apprehension-to-recognition continuum for different stimuli and under different conditions: some stimuli may be “recognized” before access but, for others, access may be initiated before recognition is complete. In other words, access to item-associated information in long-term memory (LTM) may be decoupled from recognition.
