The present study sought to investigate the extent to which masked semantic priming is an automatic process and whether its effects vary depending upon the type of stimuli used. Recent studies have shown that there is a differential priming effect for prime-target pairs with different types of semantic relationships. Here, using a semantic categorization task with masked priming, we compared the effects of synonym, antonym,and associatively related non-exemplar prime-target pairs when presented at different stimulus onset asynchronies (SOAs). Participants took a prime visibility posttest in conjunction with the categorization task which served as a measure of "partial awareness" of the prime. The results here indicate that differences in perceptual awareness may produce differential semantic priming patterns across the semantic relationships and SOAs considered. Potential mechanisms for this divergence are proposed.

In accordance with spatial mapping theory and findings from the Morris Water Maze (WMW), we predicted that older humans would differ from younger humans on a place learning task. Using a computerized version of the MWM entitled the Computer-Generated Arena, we compared performance of adults 22-29 years of age (yoa) with adults 64-81 yoa. We found that 22-29 yoa adults located an invisible target more quickly and accurately than 64-81 yoa adults. Additionally, removing sets of distal stimuli severely disrupted performance in 64-81 yoa adults, but not 22-29 yoa adults. In a post C-G Arena puzzle task, both groups of adults accurately recreated the spatial configurations of stimuli, but the 64-81 yoa adults did not place the target accurately within that space. This suggests that 64-81 yoa adults can accurately map a novel space but may not be able to place learn. These results correlate highly with performance in a real-world MWM task testing the same population.

Letter position plays an important role in lexical access. But are some positions more important than the others? Findings from numerous studies support the notion that in lexical access, initial letters produce strongest activation, which weakens towards the end of the word. In order to create a metric for computing the activation produced by each letter position in a correctly spelled word versus a word in which some or all letters are transposed, the formula for calculating a word's orthographic match coefficient (OMC) was developed and tested. Utilizing the masked priming paradigm and a lexical decision task, Experiments 1-5 test the accuracy and reliability of the OMC predictions, and look at neighborhood density in conjunction with different types of letter movement. Results from these experiments provide empirical support for the OMC as a reliable predictor of priming that involves transposed letters, and offer insight into possible mechanisms of word recognition.