Ownership changes how your brain judges worth. When something belongs to you, a mental shortcut kicks in that ties value to possession — and that shortcut isn't always accurate. People tend to place a higher price on items they own than on identical items they do not. You can test this directly by giving participants the same mug, changing only whether they get to keep it, then comparing the two sets of estimates.

The halo effect is a mental shortcut where one quality shapes your entire impression of a person. This project puts that bias to the test. Three people each tell a personal story in a friendly way on video, then record the same story again with a single change — a different tone of voice or slouched posture. Participants watch both versions and rate each person's likability on a scale of 1 to 10. Comparing the average ratings shows how one small shift in delivery can skew the overall perception of someone.

A single red light in a row of green ones seems to last longer than the rest. That's the oddball effect — a mental shortcut that makes unexpected events feel stretched in time. To test it, set up a slideshow of 15 to 20 images sharing a common theme, with one oddball slide hidden near the end. Every slide stays on screen for the same duration. After the show, ask each participant how long the oddball slide lasted. Most will guess it appeared longer, even though the timing was identical. The surprise breaks the pattern, and the brain misjudges the time.

Lifting a heavy book first can make a lighter one feel even lighter than it really is. The brain uses a mental shortcut that compares new input to recent experience rather than judging it on its own — and that comparison isn't always accurate. To test how sequence shapes perception, four groups each estimate the weight of two books. Group A lifts the lighter book first, Group B lifts the heavier one first, and Groups C and D each lift only one. Comparing the average estimates across all four groups shows how the order in which you experience different magnitudes changes how you judge the same object.

When someone tells you an expert picked a certain brand as the best, your brain may lean toward that choice even if your own taste buds disagree. That pull is cognitive bias, a mental shortcut that leads your brain to judge things in ways that aren't fair or accurate. This project tests that idea by splitting people into groups: one picks freely, one hears an expert opinion first, and one must also explain their choice. Comparing the groups shows whether outside opinions nudge people away from what they actually prefer.