Most people will quickly spot the toothbrush on the front of the counter, but take longer — or even fail to find — the much bigger one behind it.

The oversight has to do with scale. People have a tendency to miss objects when their size is inconsistent with their surroundings, according to a recent study in Current Biology. This is just the latest in a robust body of research that reveals how expectations dramatically affect our ability to notice what’s around us.

Though the image above was provided by the authors of the study to illuminate their point, the study was set up slightly differently. The researchers were interested not only in what people saw — but also in how their performance compared with computers.

Flesh-and-blood participants and a deep neural network, a computer system with advanced machine vision, were given one second to select an object in a computer-rendered scene, such as the one below. The object could be absent, presented at scale or featured at four times scale.