Hemispheric asymmetry,early visual processes,and serial memory comparison

Observers indicated whether a single probe letter presented to the left visual field/right hemisphere (LVF-RH) or to the right visual field/left hemisphere (RVF-LH) matched one of two, three, four, or five set letters in both name and case. For positive trials during the initial experimental session, the slope of the linear memory set size reaction time function was increased by perceptually degrading the probe letter on LVF-RH trials, but not on RVF-LH trials. In addition, perceptual degradation of the probe letter increased the intercept of the memory set size function more on RVF-LH trials than on LVF-RH trials. During subsequent experimental sessions, the same pattern of intercept results was obtained but perceptual degradation of the probe no longer changed the slope for either LVF-RH or RVF-LH trials. However, the slopes were uniformly lower on RVF-LH trials than on LVF-RH trials. The major results are consistent with hypothesized right-hemisphere efficiency for early processing stages and left-hemisphere efficiency for serial processing of alphanumeric information. The results further illustrate the importance of separating stages of processing in studies of cerebral laterality and indicate that the relative difficulty of the various stages can be a determinant of laterality results.     

Collaboration in Recall: Do Pairs of People Cross-cue Each Other to Produce New Memories?

When people collaborate over their recall of a shared experience, it might be expected that they could “cross-cue” each other so as to produce new memories not available to either member of the pair on their own. In a previous series of experiments (Meudell et al., 1992), we found that pairs of people always recalled more than one person, but we failed to show that social interaction facilitated performance so as to produce such “emergent” new memories. However, a phenomenon akin to cross-cuing was employed by Tulving and Pearlstone (1966) in their classic study of the availability and accessibility of memories; accordingly, in this study, we repeated Tulving and Pearlstone's work directly in a social context. So as to assess whether new memories emerged in collaborating pairs, a sequential design was employed. People learned categorized lists of words, and then all the subjects recalled the items strictly on their own. Subjects then recalled again in pairs (collaboratively) or once more on their own. The results showed that even when the opportunity for cross-cuing was directly manipulated through the provision of categorized lists, no additional new memories emerged in the collaborating groups. Possible mechanisms for the results are considered.