The Reicher-Wheeler Paradigm
This lab activity introduces you to a paradigm developed by G. Reicher and D. Wheeler to study the word superiority effect. This is a phenomenon where people are better able to detect a specific letter, like “O,” when it is part of a string of letters that forms a word, as in “STOP,” compared to when it is embedded with other letters that do not produce a word, as in “OSTP.” The effect is observed when the stimulus is presented so briefly that the person is not aware of what they saw.
Fast Masked Presentation
This activity consists of 10 practice trials with feedback, followed by 80 experimental trials without feedback. On each trial, you will be quickly presented with a string of letters followed by a mask (e.g., ####). The mask serves to erase any after-image of the letters that may linger in your visual system. For example, you may see “BUMP” followed quickly by “####” to mask the four letters. Then you will be presented with “U O” in individual boxes and you must choose which of those two letters you think you saw. The answer is obviously “U” not “O.” “BUMP” is a word but what if you were shown “AUPM,” which is not a word, and then were asked “U O.” Since “AUPM” is not a word then on average one should be less accurate at indicating that you saw “U.”
Spreading Activation
Not surprisingly results from the Reicher-Wheeler paradigm consistently show better accuracy in the word compared to nonword condition even when presentation is so quick that participants report they cannot see the words. There are two response options on each trial, so chance performance is 50%. Participants usually score significantly above chance on word trials and worse, just above chance, on nonword trials. Why this pattern? Cognitively, it is thought that activation spreading from the word level to the letter level adds to any activation resulting from seeing the physical features, albeit briefly, of the letters. When there is a non-word, there is no additional spreading from a word to letter level, only activation from seeing physical features of letters that do not form a word.
Modulating the Word Superiority Effect
What do you think would happen if participants were instructed only to pay attention to the fourth letter presented on each trial? Knowing where to look causes the word superiority effect to disappear (Johnston and McClelland 1973). This probably happens because by focusing on one letter participants do not process the whole word and therefore do not benefit from activation spreading from the word level to the letter level. There are also some situations, including commonly misspelled words, in which a nonword can provide more information about the letters than the word. Consider a real word with an unusual spelling like “LIMB” compared to a nonword that is a homophone of a real word, such as “MEEN.” In this unusual condition, participants may detect more often that there is an “M” in MEEN than an “M” in “LIMB.”