Claude text watermarks will “nudge” its word choices. Should we care?

“To a reader, a watermarked response is indistinguishable from an unwatermarked one,” Anthropic said. “In internal testing, we’ve seen no impact of watermarking on the content, level of creativity, or readability of Claude’s text.”

Claude’s text watermarks, which are coming in response to the recently adopted EU AI Act, will employ a “version” of Google DeepMind’s SynthID-Text process, which “changes the source of the randomness used to pick among words.”

As Anthropic explains, Claude’s method of writing is similar to other LLMs: It generates each word one at a time, calculating the probability of each subsequent word and then picking from among the most likely choices.

In some cases, such as responses with factual information, there may only be one good choice for a given word. For example, if you ask Claude who was the first human on the moon, there will be an obvious best choice for the next word after “Neil.” Similarly, ask Claude what 2 + 2 is, and “4” will be the “very clear best choice” for the next word, Anthropic says.

But (in an example served up by Anthropic), when generating a sentence about a cloudy weather forecast, Claude might have a range of likely next words in the sentence “It’s going to be a…” The word “grey” could be a top choice with a 30-percent probability (I’m making that percentage up for argument’s sake), as well as “overcast” with a 28-percent probability.

Even without watermarking, Claude won’t necessarily pick the word “gray” just because it has a higher probability ranking than “overcast.” In a close contest like this one, the word Claude eventually chooses comes down to a roll of the dice.