Contextual information influences the feeling of knowing in episodic memory.

The feeling of knowing (FOK) predicts the likelihood of eventually recognizing currently unrecalled items. Koriat (1993, 1995) showed that retrieval of partial target information influences FOK ratings. Building on Koriat's view, the noncriterial-recollection hypothesis contends that contextual information influences FOKs (Brewer, Marsh, Clark-Foos, & Meeks, 2010). Our study assessed the validity of the noncriterial-recollection hypothesis by controlling the amount of potentially-retrievable contextual information presented to participants. We varied the amount of contextual information accompanying the name and image of imaginary animals. There were three information conditions: minimum (name and image), medium (name, image, and country), and maximum (name, image, country, diet and weight). Information condition did not affect recall accuracy. The minimum condition resulted in greater response output (recall and commission errors together). FOKs for unrecalled items were lower in the minimum condition than the other conditions. Consistent with the noncriterial-recollection hypothesis, FOKs were positively correlated with the retrieval of contextual information.

Rectal immunization with rotavirus virus-like particles induces systemic and mucosal humoral immune responses and protects mice against rotavirus infection.

To evaluate whether the rectal route of immunization may be used to provide appropriate protection against enteric pathogens such as rotaviruses (RV), we studied the antibody response and the protection induced by rectal immunization of mice with RV virus-like particles (VLP). For this purpose, 6-week-old BALBc mice were rectally immunized twice with RV 8-2/6/7-VLP derived from the bovine RV RF81 strain either alone or combined with various adjuvants including four toxins [cholera toxin (CT) and three attenuated Escherichia coli-derived heat-labile toxins (LTs), LT(R192G), LT(R72), and LT(K63)] and two Toll-like receptor-targeting adjuvants (CpG and resiquimod). Six weeks after the second immunization, mice were challenged with murine RV strain ECw. RV VLP administered alone were not immunogenic and did not protect mice against RV challenge. By contrast, RV VLP combined with any of the toxin adjuvants were immunogenic (mice developed significant titers of anti-RV immunoglobulin A [IgA] in both serum and feces and of anti-RV IgG in serum) and either efficiently induced complete protection of the mice (no detectable fecal virus shedding) or, for LT(K63), reduced the amount of fecal virus shedding after RV challenge. When combined with RV VLP, CpG and resiquimod failed to achieve protection, although CpG efficiently induced an antibody response to RV. These results support the consideration of the rectal route for the development of new immunization strategies against RV infection. Rectal delivery of a VLP-based vaccine might allow the use of adjuvants less toxic than, but as efficient as, CT.