Tailored information display: Effects of background colour and line spacing on visual search across different character types – An eye-tracking study

Abstract

In the era of expanding digital information, optimizing display factors has become increasingly critical for human–computer interaction. However, the broader impacts of background colour and line spacing on interfaces with different character types, under controlled luminance contrast remain underexplored. This study investigates the effects of background colour and line spacing on search performance, eye-tracking metrics, and subjective reports across English, Chinese, and numerals in controlled luminance conditions using a pseudo-text visual search task. Findings reveal the distinct impacts and mechanisms for each character type. Red background significantly hindered search performance, particularly in English, while cyan improved accuracy and subjective ratings across all characters. Colour difference emerged as a critical determinant of visual comfort, and its influence is moderated by pupil diameter. Double line spacing provided an optimal balance between search performance and minimizing eye movement effort, further increases in line spacing impair search speed, especially in numerals. Fixation duration and fixation count mediated the effects of line spacing on legibility in numerals and English, respectively. These findings offer actionable insights for optimizing interfaces with different character types and highlight the need to explore further how display factors contribute to visual experience in complex scripts.