Neighborhood Density Effects in CSL Sign Recognition: Location, Handshape, and Movement Diverge

Most spoken word recognition models assume that a target word co-activates phonologically similar neighbors that compete for recognition, a process reflected in inhibitory neighborhood density effects. Sign languages provide a critical test for the generality of these mechanisms with simultaneously articulated phonological parameters like location, handshape, and movement, as well as prevalent iconic form-meaning mappings. The present study employed a lexical decision task in Chinese Sign Language to investigate how density defined over each parameter affects recognition and whether subjective lexical frequency modulates these effects. Results showed that location density inhibited reaction times for both signs and non-signs, consistent with competition among lexical representations activated through shared sublexical location features. Handshape density facilitated accuracy selectively for lower-frequency signs, probably reflecting a late decisional strategic bias driven by the familiarity of typical handshape values under weak competition. Movement density showed no significant effects, while subjective lexical frequency robustly facilitated reaction times and accuracy, validating task sensitivity. The results suggest that parameters are used differently during lexical sign recognition, likely due to different perceptual timing and resting activation levels. They are also consistent with spoken word recognition principles of neighbor competition and frequency modulation, implying some shared lexical recognition mechanisms across modalities.