Morpheme Position Coding in Reading Development as Explored With a Letter Search Task

Suffixes have been shown to be recognized as units of processing in visual word recognition and their identification has been argued to be position-specific in skilled adult readers: in lexical decision tasks suffixes are automatically identified at word endings, but not at word beginnings. The present study set out to investigate whether position-specific coding can be detected with a letter search task and whether children already code suffixes as position-specific units. A preregistered experiment was conducted in Italian in which 3rd-graders, 5th-graders, and adults had to detect a target letter that was either contained in the suffix of a pseudoword (e.g., S in flagish) or in a non-suffix control (e.g., S in flagosh). To investigate sensitivity to position, letters also had to be detected in suffixes and non-suffixes placed in reversed position, that is in the beginning of pseudowords (e.g., S in ishflag vs. oshflag). Results suggested position-specific processing differences between suffixes and non-suffixes that develop throughout reading development. However, some effects were weak and only partially compatible with the hypotheses. Therefore, a second experiment was conducted. The effects of position-specific suffix identification could not be replicated. A combined analysis additionally using a Bayesian approach indicated no processing differences between suffixes and non-suffixes in our task. We discuss potential interpretations and the possibility of letter search being unsuited to investigate morpheme processing. We connect our example of failed self-replication to the current discussion about the replication crisis in psychology and the lesson psycholinguistics can learn.