When you’re scanning a room for your keys without your glasses, you’re doing more than searching—you’re weighing cognitive reliabilities. Is that blur on the table your keys? Or do you have more trust in your memory that you left them in the drawer? 

That everyday moment (and many others) sits at the centre of new research led by Trent University and published in Nature Human Behaviour, exploring how the brain compares confidence across two very different systems: perception (what we see now) and memory (what we recall from before). 

For decades, psychologists have treated these as separate forms of thinking. Perception processes the present. Memory reconstructs the past. Each has its own mechanisms and its own way of being studied. 

This research is the first to suggest something deeper connects them. 

A common language for confidence

Across two studies involving more than 500 participants (and including children as young as four), researchers tested how people evaluate confidence in different situations. Participants completed simple memory tasks (recalling pictures of objects) and perception tasks, such as judging which of two shapes was larger. Then came the key question: which answer do you trust more? 

“People were just as consistent when comparing across memory and perception as they were within them,” says Dr. Carolyn Baer, professor of Psychology at Trent University and lead author on the study. “The mind appears to convert different types of uncertainty into a shared ‘unit’ of confidence, allowing us to make decisions across fundamentally different kinds of information.” 

Built early, used constantly

The same pattern held for children. Even at age six, participants could compare confidence across memory and perception with similar accuracy to adults, pointing to a system that develops early and shapes how we navigate uncertainty. 

Researchers also found that individuals who were overconfident in perception tended to show the same bias in memory, and vice versa. While the sources of information differ, the way confidence is expressed remains consistent. 

Translating without language

The research also challenges a long-standing assumption about how the brain integrates information. 

Language has often been seen as the bridge between different cognitive systems, a way we connect thoughts, memories, and perceptions. These findings suggest another layer exists beneath that. 

“There seems to be a kind of mental translator, that coordinates different signals and converts separate streams of uncertainty into a single, comparable measure of confidence,” adds Prof. Baer. “That translation is what makes everyday decisions possible, and the findings of our research begin to understand what is happening.” 

Rethinking how we build judgment

The findings also open new questions about how confidence is learned and applied. 

“Training someone to better judge confidence in one area, like perception, may not transfer to another, such as memory,” says Prof. Baer. “But helping people calibrate how they report confidence could have broader effects.” 

For a field that has long separated memory and perception, the study offers a new way of thinking for both scientists and people, one that less about what these systems do differently, and more about what they share. 

Learn more about Psychology at Trent University.