Marine Alert Fatigue Study

🐟 This quiz is a deliberate red herring. All 5 alarm sounds are identical — because that is exactly what most MFDs do. Depth, AIS, wind, autopilot, off-course: same beep. The quiz is designed to let you experience the problem first-hand.

Why it matters: You cannot prioritise what you cannot distinguish. If every alarm sounds the same, the only way to know what triggered is to get up, walk to the screen, and read it. At 3 AM that delay can be the difference between a course correction and a collision.

What you will experience: You will hear 5 alarms and try to identify each one. You will almost certainly fail — not because of your ears, but because the sounds are genuinely indistinguishable. That is the point.

What it measures: A sailor's ability to detect visual changes on the horizon after a simulated night-vision disruption. The participant views a night scene, a white flash simulates a glare event, and they must identify what changed.

Why it matters: At night, a single glance at a bright screen resets dark-adapted vision, requiring up to 20–30 minutes to recover full sensitivity. This instrument measures how well sailors detect changes (new vessel, altered course, missing light) after such disruption.

What it measures: The ability to prioritise cascading alerts when multiple alarms fire simultaneously. Alerts appear with colour-coded severity and countdown timers. The participant must tap the highest-priority alert before time expires.

Why it matters: In a real alarm cascade, the critical alert is buried among routine ones. This instrument measures how accurately and quickly sailors can identify what matters most when everything is demanding attention at once.

What it measures: Whether sailors understand how quickly different maritime scenarios escalate from routine to critical. Participants rank 12 scenarios (drawn from a pool of 15) across 4 rounds by the speed at which they become dangerous.

Why it matters: Incorrect mental models of escalation speed lead to delayed responses. A dragging anchor in a crowded anchorage escalates faster than most sailors assume. This instrument reveals those gaps.

What it measures: A sailor's ability to design safe watch rotation schedules based on crew size, weather conditions, fatigue factors, and passage type. Eight passage scenarios test understanding of circadian rhythm impact, seasickness management, novice crew integration, and recognition of fatigue blindness.

Why it matters: Poor watch rotation is a leading contributor to fatigue-related incidents at sea. Two-person crews on overnight passages, odd-numbered crew rotations, and the notorious "death watch" (0200–0600, spanning the circadian nadir) each demand different scheduling strategies that many skippers have never formally considered.

What it measures: A sailor's ability to deduce which alarm woke them based on instrument readings and environmental clues. Each scenario presents a 3 AM cabin scene with visible instruments, and the participant must identify the alarm source.

Why it matters: When woken at 3 AM by an unidentified alarm, crew must rapidly diagnose the source to determine the correct response. Misidentification wastes critical time or causes an inappropriate reaction.

What it measures: Alarm habituation — whether a participant's response behaviour drifts when false alarms dominate. Across 3 phases with increasing false alarm rates, the instrument tracks whether the participant continues to respond to genuine critical alarms or begins ignoring them.

Why it matters: The "cry wolf" effect is well-documented in clinical settings, where 85–99% of hospital alarms are false or non-actionable and staff stop responding — including to genuine emergencies. This instrument tests whether even moderate false alarm rates (up to 70%) produce the same behavioural drift in sailors.

What it measures: Simple reaction time and its degradation over a sustained session, inspired by the Psychomotor Vigilance Task (PVT) used in fatigue research. The participant responds to alarm stimuli as quickly as possible across 3 blocks of 10 trials.

Why it matters: Reaction time is the most direct measure of vigilance. The PVT is the gold standard in sleep and fatigue research. This marine-contextualised version measures whether reaction time degrades over even a short sustained-attention session — a preview of what happens during a 4-hour night watch.

What it measures: Sustained auditory attention using the classic oddball paradigm. A repeating standard tone plays continuously; the participant must detect when a rare target tone (the "oddball") appears among the standards.

Why it matters: The oddball paradigm measures the brain's ability to maintain attention to a monotonous stream and detect deviations. On a boat, this is exactly what watch-keeping demands — hours of routine punctuated by rare events that require immediate recognition.

What it measures: Alert priority sorting under progressively escalating time pressure. Across 4 phases, alerts arrive faster and overlap more, measuring the point at which triage accuracy breaks down.

Why it matters: In real alarm cascades, the rate of incoming alerts increases as systems fail. This instrument identifies the threshold at which a sailor's triage ability degrades — the point where they start missing critical alerts or responding to the wrong ones.

What it measures: Alarm discrimination under perceptual convergence. Genuine alarms and false alarms are initially easy to distinguish, then become progressively more similar. The participant must act on genuine alarms (Go) and suppress responses to false alarms (No-Go).

Why it matters: As alarm systems age or are poorly configured, the visual and auditory cues that distinguish critical from routine alerts degrade. This instrument measures how well sailors maintain discrimination accuracy as the signals converge.

What it measures: Audio discrimination and action mapping. After a brief training phase where participants learn 5 distinct alarm sounds and their associated responses, they must correctly identify each alarm and select the appropriate action under time pressure.

Why it matters: Knowing what an alarm means is only useful if you can recall the correct response. This instrument measures the complete alarm-to-action chain: hear, identify, and act correctly.

What it measures: Dual-task attention — the ability to maintain a primary task (compass heading correction) while detecting peripheral threats (navigation lights appearing at screen edges). Across 3 phases, the demands increase.

Why it matters: On watch, a sailor must simultaneously monitor instruments, maintain course, and scan the horizon. This instrument measures the dual-task cost — how much peripheral detection degrades when the primary task demands attention.

What it measures: Spatial working memory — the ability to remember vessel positions after a radar display goes dark. Each round shows vessels on a radar screen for a brief period, then the screen blanks and the participant must recall where each vessel was.

Why it matters: When radar fails, AIS drops out, or visibility closes in, the only thing keeping you safe is your mental model of where other vessels were. This instrument measures that spatial memory capacity under increasing load (3 to 5 vessels).

What it measures: A sailor's ability to identify independent failure modes in smartphone-based anchor alarm systems. 10 cockpit scenarios at 3 AM — 7 are genuine risks, 3 are safe. Participants classify each as "Risk" or "Safe."

Why it matters: The scenarios are drawn from documented failure modes catalogued in our analysis of smartphone anchor alarm failures. False alarms (marking safe items as risks) are tracked separately to measure over-alertness bias.

What it measures: Chart symbol identification speed and accuracy. SVG-rendered chart symbols appear with time pressure, and the participant must classify each as "Danger" or "Safe" before time runs out.

Why it matters: Chartplotter symbols are the visual language of electronic navigation. Misreading a wreck symbol as a buoy, or not recognising a restricted area, has direct safety consequences.

What it measures: Vessel identification by navigation light configuration at night. Approaching vessels display their navigation lights, and the participant must identify the vessel type and aspect.

Why it matters: At night, navigation lights are the primary means of identifying other vessels and determining their course. Correct identification determines whether you need to give way, stand on, or take evasive action.

What it measures: The ability to read AIS data and identify which vessel is on a collision course. Each scenario presents multiple AIS targets with CPA (Closest Point of Approach) and TCPA (Time to CPA) data.

Why it matters: AIS provides rich data, but only if you can interpret it quickly. Identifying which of several vessels poses the greatest collision risk is a critical decision that must be made in seconds, not minutes.

What it measures: The ability to identify radar echoes without AIS overlay. Raw radar returns are displayed and the participant must identify what each echo represents — vessel, land, buoy, rain, or sea clutter.

Why it matters: When AIS fails or targets are non-transmitting, radar is the last electronic line of defence. Reading raw radar returns is a skill that many sailors have lost as they rely increasingly on AIS overlay.

What it measures: MOB (Man Overboard) response knowledge with a real-time drift penalty. Each scenario presents a MOB situation and multiple response options. Wrong answers accumulate drift time — every second of delay equals 3 metres of drift.

Why it matters: In a real MOB event, the clock starts the moment someone goes over. The drift penalty makes this instrument visceral — incorrect responses don't just lose points, they lose distance to the person in the water.

What it measures: Application of the International Regulations for Preventing Collisions at Sea (COLREGs). Each encounter presents two vessels and the participant must determine who gives way and who stands on.

Why it matters: COLREGs are the rules of the road at sea. Misapplication leads to close-quarters situations and collisions. This instrument tests practical application under time pressure across a wide range of encounter types.

What it measures: How well sailors really sleep at anchor — covering anchor watch habits, alarm usage, weather anxiety, anchorage selection, and sleep disruption patterns. Participants receive a personalised sleep profile based on their responses.

Why it matters: Anchor anxiety is one of the most commonly reported sources of poor sleep among cruising sailors, yet it is rarely studied. Understanding these patterns helps us design better alert systems that let sailors rest with confidence.

What it measures: How well recreational sailors retain the International Regulations for Preventing Collisions at Sea (COLREGs) — years after their original training. 13 scored questions cover right-of-way, sound signals, light configurations, and restricted visibility.

Why it matters: Research focuses heavily on professional mariners, but recreational sailors face the same encounters with far less ongoing training. This survey reveals the gap between perceived and actual knowledge — a Dunning-Kruger effect in maritime navigation.

What it measures: How sailors manage fatigue during offshore passages — covering watch-keeping systems, sleep banking, fatigue self-assessment, and decision-making under sleep deprivation. Participants receive a fatigue management profile.

Why it matters: Most sailors believe they handle fatigue well on passage. The science suggests otherwise. This survey explores the gap between self-perception and evidence-based fatigue management, helping identify where better systems and alerts could make a difference.