Calendar Horizon as a Boundary Affordance: An Attempt-Centric Eye-Tracking Analysis of Calendar Scheduling Interfaces

TL;DR

This study explores how the visibility of weekends in calendar interfaces affects scheduling behavior and attention patterns.

Contribution

The paper introduces calendar horizon as a boundary affordance and demonstrates its impact on scheduling processes and outcomes.

Findings

Each additional scheduling attempt increased total fixation duration by ~56%.

Personal tasks required more attempts and elicited stronger weekend verification in the Late phase.

Hiding the weekend reduced weekend placements and increased evening scheduling.

Abstract

Digital calendars are interactive representations of time that shape both scheduling outcomes and the micro-process of searching, verifying, and revising candidate placements. We examine calendar horizon—whether weekend time is visible in the default week view—as a boundary affordance in scheduling interfaces. Using eye tracking and interaction logs, we model each scheduling episode as a sequence of placement attempts and align gaze to each attempt, partitioning it into Early/Mid/Late phases and summarizing attention across structural AOIs (task panel, calendar grid, and the weekend column when present). Two experiments used drag-and-drop and dropdown slot-picking; weekend visibility was manipulated within the dropdown interface, while evening slots remained available. Across 105 participants (1018 task episodes), AttemptsCount ranged from 1 to 7. AttemptsCount predicted gaze-based process cost: each additional attempt corresponded to ~56% more total fixation duration. Personal tasks required more attempts than work tasks and elicited stronger Late-phase weekend verification when the weekend was visible. Horizon cues also shifted boundary outcomes: hiding the weekend reduced weekend placements and increased reliance on evening scheduling, indicating displacement into adjacent time regions. These findings position calendar horizon as a design lever that shapes both process (verification) and outcomes (boundary placements), with implications for calendar UIs and mixed-initiative scheduling tools.

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