Buzz Lightyear froze when encountering humans in Toy Story even though he failed to believe he was a toy, but there might be plausible explanations that fix the perceived plot hole. Tim Allen voiced the Space Ranger toy for all four Pixar installments in the Toy Story franchise. Unlike the rest of the toys residing in Andy's bedroom in the 1995 debut movie, Buzz believed he was a real astronaut, not a children's plaything. It took strong convincing from Woody (Tom Hanks) and fellow toys to make the Ranger learn the truth.
Buzz was the newcomer in Toy Story after he was given to Andy as a birthday present. Modeled after a skilled astronaut, Buzz was convinced he was sent to another galaxy when in reality, he was just another toy. Woody, the cowboy doll, was initially jealous of Buzz's status as Andy's favorite toy, leading to the pair's capture by the sinister next-door neighbor, Sid. During the big escape, Buzz bluntly came to the realization that he wasn't a real Space Ranger. Granted, by the end of the movie, Buzz embraced his status as a toy and even became a voice to fellow Buzz toys when they acted as though they were real astronauts in Toy Story 2.
Considering Buzz went through Toy Story convinced he was a Space Ranger sent on a mission, there was confusion as to why he froze around Andy and other humans. To hide the fact they were sentient beings, the toys would instantly revert to their toy-like status in the presence of humans. Based on Buzz's belief in being human himself, there was a common thought that he shouldn't have froze as that's only a response used by real toys. Even Pixar's chief creative officer, Pete Docter, spoke on the matter, claiming the crew didn't care enough to directly explain Buzz's behavior. While it's considered one of the most-talked-about Pixar plot holes, the Toy Story detail could very well stem from Buzz's programming.
Since Buzz was a toy just like the rest of the inhabitants of Andy's room, he may have had the instinct to stop moving around his owner. This instinct could very well be linked to Buzz's programming as an official Space Ranger toy. As showcased in Toy Story, Buzz was more technically advanced than some of Andy's already-owned toys. The Space Ranger's functionality was later revealed to be updated with a special Utility Belt in Toy Story 2. It's very possible the programming inside Buzz gave him the instinct to freeze around humans even though that same programming convinced him he wasn't a toy. Programming was a major faction in Buzz's wiring considering the advanced Buzz Lightyears seen later in the Toy Story timeline and Buzz's Spanish-speaking phase after being reprogrammed in Toy Story 3.
That same instinct theory can also be taken a step further with Buzz's astronaut programming. When taken out of the box, Buzz eventually came "alive," but he was convinced he crash-landed on an alien planet. When observing his peers–the fellow toys–freeze around large humans, Buzz may have copied them to culturally fit in with the unknown lifeforms. To not threaten his "mission," Buzz did what he had to do, even if it meant playing along in the presence of humans. If something weren't keeping Buzz from coming alive in the hands of Andy, his cover would have been blown. Though it's understandable why Buzz's behavior could be viewed as a Toy Story plot hole, those toys might have been more dynamic than initially thought.
