MODELDRIFT.WATCH

Sep 30 · Day 21

MINOR · GEMINI · QUESTION 7

Gemini took 22 seconds to answer a request to explain refrigerators in plain prose, against its usual 12 seconds.

Why it’s minor

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 29beforePermalink

A refrigerator keeps things cold not by creating coldness, but by removing heat from its interior and releasing it into the surrounding room. This continuous process relies on the principles of evaporation and condensation, using a specially formulated chemical fluid called a refrigerant that circulates through a closed loop of copper tubes and machinery.

The cycle begins at the compressor, which acts as the heart of the cooling system. The compressor draws in cool, low-pressure refrigerant gas and squeezes it, which significantly increases both the pressure and the temperature of the fluid. This hot, high-pressure gas then flows into the condenser coils, which are typically located on the back or underneath the appliance. As the hot gas travels through these exposed coils, it releases its heat into the ambient air of the kitchen. Losing this thermal energy causes the refrigerant to condense, changing from a gas into a warm, high-pressure liquid.

This liquid refrigerant then moves toward the interior of the fridge, passing through a tiny opening called an expansion valve or capillary tube. Forcing the liquid through this narrow passage causes a rapid and massive drop in pressure. Physics dictates that this sudden pressure drop makes the liquid become exceptionally cold. The freezing liquid then enters the evaporator coils located inside the insulated refrigerator compartment.

As the relatively warm air from your groceries blows across these cold interior coils, the cold refrigerant absorbs that heat. This absorption of heat cools the air inside the fridge, while simultaneously causing the liquid refrigerant to boil and evaporate back into a low-pressure gas.

Finally, this cool, low-pressure gas is suctioned back down into the compressor, and the entire cycle begins again. A thermostat constantly monitors the internal temperature of the appliance, turning the compressor on when the interior gets too warm and shutting it off once the desired temperature is reached. Through this continuous loop of pressure changes and phase shifts, the refrigerator essentially acts as a heat pump, constantly migrating thermal energy away from your food and out into your home.

SEP 30afterPermalink

A refrigerator works by moving heat from its interior to the outside environment, rather than magically creating cold air. It accomplishes this through a continuous cycle of evaporation and condensation using a special chemical fluid called a refrigerant. This fluid constantly circulates through a closed system of metal tubes and mechanical components, changing between a liquid and a gas state to absorb and release heat.

The cycle begins at the compressor, which acts as the heart of the appliance. The compressor squeezes the refrigerant gas, significantly increasing its pressure and temperature. This hot, highly pressurized gas then flows into the condenser coils, which are typically located on the back or bottom of the refrigerator. As the hot gas travels through these exterior coils, it releases its thermal energy into the surrounding air of your kitchen. Losing this heat causes the refrigerant to cool down and condense into a high-pressure liquid.

Next, this liquid refrigerant moves toward the expansion valve, which is essentially a very small opening. Forcing the liquid through this narrow passage causes a sudden, massive drop in pressure. Because pressure and temperature are directly related, this pressure drop causes the refrigerant to become extremely cold. The freezing liquid then enters the evaporator coils situated inside the insulated food compartment. As a fan blows the relatively warm air from your groceries across these cold indoor coils, the liquid refrigerant absorbs that heat and evaporates back into a gas, leaving the air inside the refrigerator completely chilled.

Having absorbed the heat from the interior, the slightly warm refrigerant gas is drawn back into the compressor. The cycle immediately begins again, continuously pumping heat out of the insulated box and dumping it into the room. A built-in thermostat constantly monitors the internal temperature, signaling the compressor to turn on when the interior gets too warm and shutting the entire system off once the desired coldness is maintained.

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

Before baseline

2026-09-29 permalink

Scored
answered · format ok
Received
2026-09-29 09:01:57 UTC
Run
20260929T090007Z-334891
Served by
Google · HTTP 200 · finish stop
Size
2,201 characters · 1,242 tokens out incl. hidden reasoning · 10.6 s
A refrigerator keeps things cold not by creating coldness, but by removing heat from its interior and releasing it into the surrounding room. This continuous process relies on the principles of evaporation and condensation, using a specially formulated chemical fluid called a refrigerant that circulates through a closed loop of copper tubes and machinery.
The cycle begins at the compressor, which acts as the heart of the cooling system. The compressor draws in cool, low-pressure refrigerant gas and squeezes it, which significantly increases both the pressure and the temperature of the fluid. This hot, high-pressure gas then flows into the condenser coils, which are typically located on the back or underneath the appliance. As the hot gas travels through these exposed coils, it releases its heat into the ambient air of the kitchen. Losing this thermal energy causes the refrigerant to condense, changing from a gas into a warm, high-pressure liquid.
This liquid refrigerant then moves toward the interior of the fridge, passing through a tiny opening called an expansion valve or capillary tube. Forcing the liquid through this narrow passage causes a rapid and massive drop in pressure. Physics dictates that this sudden pressure drop makes the liquid become exceptionally cold. The freezing liquid then enters the evaporator coils located inside the insulated refrigerator compartment.
As the relatively warm air from your groceries blows across these cold interior coils, the cold refrigerant absorbs that heat. This absorption of heat cools the air inside the fridge, while simultaneously causing the liquid refrigerant to boil and evaporate back into a low-pressure gas.
Finally, this cool, low-pressure gas is suctioned back down into the compressor, and the entire cycle begins again. A thermostat constantly monitors the internal temperature of the appliance, turning the compressor on when the interior gets too warm and shutting it off once the desired temperature is reached. Through this continuous loop of pressure changes and phase shifts, the refrigerator essentially acts as a heat pump, constantly migrating thermal energy away from your food and out into your home.

End of response · 9 lines · 2,201 characters · sha256 f4f549d59dd68bd6fd106b14918cc87506fe207d8a229188c6d65a88670712b9

After this run

2026-09-30 permalink

Scored
answered · format ok
Received
2026-09-30 09:02:19 UTC
Run
20260930T090007Z-45ce12
Served by
Google AI Studio · HTTP 200 · finish stop
Size
2,054 characters · 1,302 tokens out incl. hidden reasoning · 22.2 s
A refrigerator works by moving heat from its interior to the outside environment, rather than magically creating cold air. It accomplishes this through a continuous cycle of evaporation and condensation using a special chemical fluid called a refrigerant. This fluid constantly circulates through a closed system of metal tubes and mechanical components, changing between a liquid and a gas state to absorb and release heat.
The cycle begins at the compressor, which acts as the heart of the appliance. The compressor squeezes the refrigerant gas, significantly increasing its pressure and temperature. This hot, highly pressurized gas then flows into the condenser coils, which are typically located on the back or bottom of the refrigerator. As the hot gas travels through these exterior coils, it releases its thermal energy into the surrounding air of your kitchen. Losing this heat causes the refrigerant to cool down and condense into a high-pressure liquid.
Next, this liquid refrigerant moves toward the expansion valve, which is essentially a very small opening. Forcing the liquid through this narrow passage causes a sudden, massive drop in pressure. Because pressure and temperature are directly related, this pressure drop causes the refrigerant to become extremely cold. The freezing liquid then enters the evaporator coils situated inside the insulated food compartment. As a fan blows the relatively warm air from your groceries across these cold indoor coils, the liquid refrigerant absorbs that heat and evaporates back into a gas, leaving the air inside the refrigerator completely chilled.
Having absorbed the heat from the interior, the slightly warm refrigerant gas is drawn back into the compressor. The cycle immediately begins again, continuously pumping heat out of the insulated box and dumping it into the room. A built-in thermostat constantly monitors the internal temperature, signaling the compressor to turn on when the interior gets too warm and shutting the entire system off once the desired coldness is maintained.

End of response · 7 lines · 2,054 characters · sha256 979d2ba410605dae18f8916a482a763f9764a9a533414a3c8282b228ae70535c

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 2026-09-30 09:00:07 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
22,167 ms against a baseline of 11,976 ms (1.9×; z = 4.1, σ = 0.15 in log units, D34 n=6)
Baseline
6 prior days with data; 6 matched the baseline value (2026-09-23, 2026-09-25, 2026-09-26, 2026-09-27, 2026-09-28, 2026-09-29)
Responses
before 2026-09-29 09:01:57 UTC, run 20260929T090007Z-334891; after 2026-09-30 09:02:19 UTC, run 20260930T090007Z-45ce12
Detected
2026-09-30 · run 20260930T090007Z-45ce12, started 2026-09-30 09:00:07 UTC · scorer v1 · severity rules r2
Permalink
https://modeldrift.watch/e/2026-09-30/D13/google/gemini-3.1-pro-preview/anomaly/latency_ms/
Event ID
2026-09-30:D13:google/gemini-3.1-pro-preview:anomaly:latency_ms

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