, 2006). Both
Wnt inhibitor perceptual and reflective attention have limited capacity, and the fact that they often trade-off suggests that they are not entirely independent. Researchers have identified some of the neural changes associated with trial-to-trial fluctuations in attention and their consequences for memory, and PRAM attempts to explain subsequent memory according to variation in either perceptual or reflective attention to different items. As described above, in studies of LTM using simple materials (e.g., words, pictures) various lateral PFC, lateral parietal, and MTL regions show greater activity for subsequently remembered than forgotten items (Blumenfeld and Ranganath, 2007, Diana et al., 2007, Kim, 2011 and Uncapher and Wagner, 2009). In contrast, greater activity for subsequently forgotten than remembered items is often found in medial PFC and medial parietal cortex (posterior cingulate, precuneus, TPJ; Kim et al., 2010, Otten and Rugg, 2001, Park et al., 2008, Turk-Browne et al., 2006 and Uncapher et al., 2011). Interestingly, these same regions are active when participants are cued to engage in reflective, self-referential, internally MS 275 oriented processing (e.g., Gusnard et al., 2001 and Ochsner et al., 2005), such as thinking about their aspirations or obligations (Johnson et al., 2006). This suggests that forgotten items in non-self-referential cognitive tasks were ones for which the participant’s attention
was momentarily diverted from the task and focused on more personal concerns. In fact,
these same anterior and posterior medial regions are spontaneously more active during “rest,” when no task at all is specified, than during many cognitive tasks (and are part of what is known as the “default network,” Raichle et al., 2001 and Buckner et al., 2008). It should be noted that when self-referential processing is relevant to a later memory task, activation in medial PFC is positively related to later memory (e.g., Macrae et al., 2004 and Kim and Johnson, 2010). Limited attention is not necessarily allocated in an all-or-none manner but may be distributed between primary (target) and other (nontarget or task-irrelevant) information (Pashler, 1998). For example, according to load theory (Lavie, 2005), the amount aminophylline of processing that nominally “unattended” stimuli receive depends on how much processing is devoted to the primary, attended target task. Difficult primary tasks (high load) consume attention; easy primary tasks (low load) do not fully consume attention, which thus spills over to process “unattended” stimuli. Consistent with load theory, increasing the perceptual difficulty of a target task can eliminate negative priming from unattended distractors (Lavie and Fox, 2000). In contextual learning tasks, increasing the difficulty of the search through attended arrays decreases implicit learning of unattended arrays (Jiang and Chun, 2001).