Keywords

heart rate variability; vigilance; sustained attention; continuous performance test; sustained attention to response task; physiological arousal

Abstract

Background: Vigilance tasks require sustained attention over long periods of time while monitoring for rare critical signals. Inverted or reverse vigilance/sustained attention response tasks (SART) may impose greater response-control demands. Although prior studies have compared these tasks behaviorally, there are fewer investigations examining whether they differ in physiological arousal as indexed by heart rate variability (HRV).

Method: Undergraduate students from UCF completed a variation of either the X-CPT (standard vigilance task) or the CPT-3 (inverted/SART) task. Electrocardiogram data was recorded continuously. Data from 40 participants were analyzed. HRV was indexed using frequency domain analysis using the low-frequency to high-frequency ratio (LF/HF) across baseline and six 5-minute task blocks. Performance was assessed using hit rate, false alarms (FA), and response time (RT). Subjective workload was measured using the NASA Task Load Index (NASA-TLX).

Results: LF/HF did not differ significantly overall between conditions, but it changed significantly across time and showed a significant block × condition interaction, indicating different physiological trajectories across task formats. The standard condition showed earlier LF/HF elevations relative to baseline, whereas the inverted condition showed a later increase across blocks. The standard condition showed a significant decline in hit rate over time, while the inverted condition did not. RT did not increase for the standard or inverted task. Participants in the inverted condition reported significantly higher mental demand, temporal demand, and frustration on the NASA-TLX.

Conclusion: The inverted vigilance task did not produce the same overt behavioral sign as the standard vigilance task (decrease in hit rate) but also did not show a pattern consistent with a speed-accuracy tradeoff (increase in RT and decrease in FA). Instead, participants maintained performance while incurring a greater physiological (LF/HF) and subjective workload cost.

Thesis Completion Year

2026

Thesis Completion Semester

Spring

Thesis Chair

Hancock, Peter

College

College of Sciences

Department

Psychology

Thesis Discipline

Psychology

Language

English

Access Status

Open Access

Length of Campus Access

None

Campus Location

Orlando (Main) Campus

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