Purpose

This study examines how an accessibility-optimised mobile interface (larger fonts, bigger targets, and simpler navigation) affects usability for Indian smartphone users aged 60+.

 Design/methodology/approach

In a within-subject experiment, participants performed tasks (finding a product, filtering, and checking out) on each interface. We recorded completion rates, errors, time-on-task, and System Usability Scale (SUS) scores. Data were analysed with paired t-tests (Wilcoxon tests if needed), using Cohen’s d and Cronbach’s alpha.

Findings

The accessibility-optimized interface received significantly higher usability satisfaction scores than the standard interface (M = 43.33 vs. 31.33; t(29) = 5.860, p < 0.001, Cohen’s d = 1.070), with improvements across all 10 SUS items. Task-based measures similarly favoured the optimized design.

Research limitations/implications

The lab setting and participant group may limit generalisability; future work should test these interventions in diverse, real-world contexts. The within-subject design provides strong evidence of interface effects.