Does neighborhood size really cause the word length effect?

Area of Science:

• Cognitive Psychology
• Experimental Psychology

Background:

• The word length effect, where short words are recalled better than long words, is a key finding in short-term memory research.
• This effect is foundational to working memory models, yet its underlying causes remain debated.
• Previous research suggested word neighborhood size might explain the word length effect.

Purpose of the Study:

• To systematically investigate whether word neighborhood size causally determines the word length effect.
• To re-examine the role of orthographic structure frequency as a potential confound in prior studies.
• To determine if the word length effect is robust when controlling for these factors.

Main Methods:

• Conducted six experiments using immediate serial recall and order reconstruction tasks.
• Utilized large word pools controlled for neighborhood size and orthographic structure frequency.
• Manipulated word length and neighborhood density across different experimental conditions.

Main Results:

• The typical word length effect was consistently observed across experiments, even when controlling for neighborhood size.
• Experiment 4 demonstrated that manipulating orthographic structure frequency could reverse the word length effect.
• However, controlling for both neighborhood size and orthographic structure frequency in Experiments 5 and 6 still yielded a significant word length effect.

Conclusions:

• The findings do not support the hypothesis that neighborhood size is the primary determinant of the word length effect.
• Orthographic structure frequency can influence the word length effect, but does not eliminate it.
• A robust word length effect in short-term serial recall remains evident even after accounting for neighborhood size and orthographic structure.