Semantic similarity makes the law underestimate real decision time

What it is

Hick's law treats response alternatives as discriminable categories. When options are highly similar in name, icon, consequence, or use context, people must make extra fine-grained distinctions and actual decision time exceeds a prediction from count or entropy alone. This semantic similarity is a key boundary of the choice model.

Why it happens

Similar alternatives share features and wording, reducing the diagnosticity of rapid recognition. People read detail, revisit descriptions, simulate consequences, or compare exceptions to rule out near neighbours. With equal count but weaker distinguishing cues, number-based uncertainty does not capture all cost; errors and low confidence rise too.

Studying it

Hold count and frequency constant while varying semantic distance in labels, icons, or function. Measure reaction time, errors, regressions, and confidence. Card sorting, similarity ratings, or interviews can verify that meaning rather than visual length changed. For high-risk work, measure whether careful checking accounts for slower decisions.

Where it stops holding

Similarity is not always harmful: a semantically coherent tool group supports categorisation. The problem is absence of cues that distinguish consequences. Experts can bypass comparison through location or shortcuts, while novices and infrequent users are more affected. Distinctiveness should not be won with arbitrary or inaccurate terminology.

Related

• Same group: B1.13.1 With unequal alternatives, decision time depends on information distribution, not count · B1.13.2 When visual search dominates, time rises linearly with option count · B1.13.3 The law covers choice among known options, not time to understand them · B1.13.4 Fewer visible options can split one choice into layers without lowering total time
• Nearby: B1.04 Hick-Hyman law · B1.07 Power law of practice
• Search terms: semantic similarity · choice confusion · label comprehension