MODELDRIFT.WATCH

Sep 17 · Day 8

SIGNIFICANT · GEMINI · QUESTION 7

Gemini took 23 seconds to answer a request to explain refrigerators in plain prose, against its usual 13 seconds.

Why it’s significant

Response time is how long an answer takes to arrive, and it rises and falls with the network and how busy the provider is. So an unusual time is worth a look but says little about the model itself.

The full answers

Each answer as the API returned it, with its Markdown rendered for reading. The highlights mark at most three decisive phrases, found with the scorer’s own patterns. Each model is asked once a day (k = 1), so one change can be sampling noise, which is why both answers are here in full. How scoring works.

Asked verbatim · Question 7

Answer in plain prose only. Do not use bullet points, headers, bold text, or lists. Explain how a refrigerator works.

SEP 16beforePermalink

A refrigerator works by removing heat from its interior and transferring it to the outside environment, rather than by magically creating cold air. This process relies on the principles of thermodynamics and uses a special chemical fluid called a refrigerant, which continuously circulates through a closed system of tubes. As the refrigerant changes back and forth between a liquid and a gas, it absorbs heat from inside the appliance and releases it into your kitchen.

The cycle begins at the compressor, which acts as the heart of the system. The compressor squeezes the warm refrigerant gas, significantly increasing its pressure and temperature. This hot, high-pressure gas then flows into the condenser coils, which are the warm tubes you can often feel on the back or underneath the refrigerator. As the hot gas travels through these exterior coils, it releases its heat into the surrounding room air. Losing this heat causes the refrigerant to condense, transforming it from a hot gas into a warm, high-pressure liquid.

Next, this liquid refrigerant travels to a capillary tube or expansion valve, which is essentially a very narrow opening. When the high-pressure liquid forces its way through this tiny gap into a lower-pressure area, it expands rapidly. This sudden drop in pressure causes the temperature of the liquid to plummet, making it extremely cold.

This freezing liquid then flows into the evaporator coils located inside the refrigerator. As the cold refrigerant moves through these interior coils, it absorbs heat from the food and air inside the fridge compartment. By absorbing this interior heat, the cold liquid evaporates, turning back into a low-pressure gas. At the same time, an internal fan blows air across these cold coils, circulating the chilled air throughout the refrigerator to keep your groceries fresh.

Finally, the low-pressure warm gas is drawn back down into the compressor, and the entire cycle starts all over again. A thermostat monitors the internal temperature of the refrigerator, automatically turning the compressor on when the inside gets too warm and shutting it off when the desired temperature is reached.

SEP 17afterPermalink

A refrigerator works by removing heat from its interior and releasing it into the surrounding room, rather than by creating cold air out of nothing. This continuous heat transfer relies on a chemical compound called a refrigerant, which constantly shifts between a liquid and a gaseous state as it travels through a closed loop of mechanical components.

The cooling cycle begins with the compressor, which acts as the heart of the appliance. The compressor pulls in low-pressure refrigerant gas and forcefully squeezes it. This compression drastically increases both the pressure and the temperature of the gas. The hot, pressurized gas is then pushed into the condenser coils, which are usually located on the back or bottom of the refrigerator. As the hot gas flows through these exterior coils, it releases its thermal energy into the cooler air of the kitchen. Losing this heat causes the gas to condense into a high-pressure liquid.

This liquid refrigerant then travels toward the expansion valve, sometimes called a capillary tube. This device forces the liquid through a very tiny opening, resulting in a sudden and massive drop in pressure. In physics, when a pressurized liquid rapidly expands, its temperature plummets. This turns the refrigerant into a remarkably cold, low-pressure liquid.

The frigid liquid then moves into the evaporator coils, which are located inside the refrigerator walls. Because the refrigerant is now much colder than the air and food inside the appliance, it absorbs heat from the interior compartment. A small fan circulates air over these cold coils to ensure the entire fridge remains evenly chilled. As the liquid refrigerant absorbs heat from the inside of the fridge, it warms up and boils, evaporating back into a low-pressure gas. This warm gas is then pulled back down into the compressor, and the entire cycle begins again, continuously pumping heat out of the food compartment to keep your groceries cold.

Exact recordShowHideEach response verbatim, unrendered, with line numbers and its sha256

Before baseline

2026-09-16 permalink

Scored
answered · format ok
Received
2026-09-16 09:02:28 UTC
Run
20260916T090004Z-fdcf7b
Served by
Google · HTTP 200 · finish stop
Size
2,166 characters · 1,300 tokens out incl. hidden reasoning · 11.8 s
A refrigerator works by removing heat from its interior and transferring it to the outside environment, rather than by magically creating cold air. This process relies on the principles of thermodynamics and uses a special chemical fluid called a refrigerant, which continuously circulates through a closed system of tubes. As the refrigerant changes back and forth between a liquid and a gas, it absorbs heat from inside the appliance and releases it into your kitchen.
The cycle begins at the compressor, which acts as the heart of the system. The compressor squeezes the warm refrigerant gas, significantly increasing its pressure and temperature. This hot, high-pressure gas then flows into the condenser coils, which are the warm tubes you can often feel on the back or underneath the refrigerator. As the hot gas travels through these exterior coils, it releases its heat into the surrounding room air. Losing this heat causes the refrigerant to condense, transforming it from a hot gas into a warm, high-pressure liquid.
Next, this liquid refrigerant travels to a capillary tube or expansion valve, which is essentially a very narrow opening. When the high-pressure liquid forces its way through this tiny gap into a lower-pressure area, it expands rapidly. This sudden drop in pressure causes the temperature of the liquid to plummet, making it extremely cold.
This freezing liquid then flows into the evaporator coils located inside the refrigerator. As the cold refrigerant moves through these interior coils, it absorbs heat from the food and air inside the fridge compartment. By absorbing this interior heat, the cold liquid evaporates, turning back into a low-pressure gas. At the same time, an internal fan blows air across these cold coils, circulating the chilled air throughout the refrigerator to keep your groceries fresh.
Finally, the low-pressure warm gas is drawn back down into the compressor, and the entire cycle starts all over again. A thermostat monitors the internal temperature of the refrigerator, automatically turning the compressor on when the inside gets too warm and shutting it off when the desired temperature is reached.

End of response · 9 lines · 2,166 characters · sha256 1628711f26798f6b35f4956ddd14d0703bbbd1139ac01f7a4e03067f60e54cfc

After this run

2026-09-17 permalink

Scored
answered · format ok
Received
2026-09-17 09:02:47 UTC
Run
20260917T090022Z-136fc3
Served by
Google AI Studio · HTTP 200 · finish stop
Size
1,959 characters · 1,261 tokens out incl. hidden reasoning · 23.2 s
A refrigerator works by removing heat from its interior and releasing it into the surrounding room, rather than by creating cold air out of nothing. This continuous heat transfer relies on a chemical compound called a refrigerant, which constantly shifts between a liquid and a gaseous state as it travels through a closed loop of mechanical components.
The cooling cycle begins with the compressor, which acts as the heart of the appliance. The compressor pulls in low-pressure refrigerant gas and forcefully squeezes it. This compression drastically increases both the pressure and the temperature of the gas. The hot, pressurized gas is then pushed into the condenser coils, which are usually located on the back or bottom of the refrigerator. As the hot gas flows through these exterior coils, it releases its thermal energy into the cooler air of the kitchen. Losing this heat causes the gas to condense into a high-pressure liquid.
This liquid refrigerant then travels toward the expansion valve, sometimes called a capillary tube. This device forces the liquid through a very tiny opening, resulting in a sudden and massive drop in pressure. In physics, when a pressurized liquid rapidly expands, its temperature plummets. This turns the refrigerant into a remarkably cold, low-pressure liquid.
The frigid liquid then moves into the evaporator coils, which are located inside the refrigerator walls. Because the refrigerant is now much colder than the air and food inside the appliance, it absorbs heat from the interior compartment. A small fan circulates air over these cold coils to ensure the entire fridge remains evenly chilled. As the liquid refrigerant absorbs heat from the inside of the fridge, it warms up and boils, evaporating back into a low-pressure gas. This warm gas is then pulled back down into the compressor, and the entire cycle begins again, continuously pumping heat out of the food compartment to keep your groceries cold.

End of response · 7 lines · 1,959 characters · sha256 9906be9cdd319c364427cd932fe42968f6ac7e6c744f201627ab0531e3f43b7d

Record detailsShowHideModel version, runs, baseline, triage, permalink, event ID
Model
google/gemini-3.1-pro-preview
pinned google/gemini-3.1-pro-preview-20260219; alias resolved to google/gemini-3.1-pro-preview-20260219 at 2026-09-17 09:00:21 UTC (matches the pin)
Prompt
Question 7: D13 (drift)
Why this question
The question forbids lists, headers and bold, so using them anyway is a failure to follow instructions.
Scored
format ok if the response writes plain prose without lists, headers or bold
Change
23,175 ms against a baseline of 12,944 ms (1.8×; z = 3.88, σ = 0.15 in log units, D34 n=7)
Baseline
7 prior days with data; 7 matched the baseline value (2026-09-10, 2026-09-11, 2026-09-12, 2026-09-13, 2026-09-14, 2026-09-15, 2026-09-16)
Responses
before 2026-09-16 09:02:28 UTC, run 20260916T090004Z-fdcf7b; after 2026-09-17 09:02:47 UTC, run 20260917T090022Z-136fc3
Detected
2026-09-17 · run 20260917T090022Z-136fc3, started 2026-09-17 09:00:22 UTC · scorer v1 · severity rules r2
Permalink
https://modeldrift.watch/e/2026-09-17/D13/google/gemini-3.1-pro-preview/anomaly/latency_ms/
Event ID
2026-09-17:D13:google/gemini-3.1-pro-preview:anomaly:latency_ms

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