A psychologist has discovered a new way to tell someone’s blackjack hand – their eye movements.

Dr Holmes, a psychologist at Colorado College, tested his hypothesis that people’s eye movements would indicate someone’s hand. He based his hypothesis on other studies that demonstrated that when people perform a mental calculation and then point to that number on a horizontal line from 0 to 100, they were more likely to indicate left of the real answer when subtracting and right of the real answer when adding, even when the answer was the same number.

From this, Dr Holmes sought to discover if a person’s eye movements worked in the same way. He and his colleagues asked 58 volunteers to play the game by themselves in a darkened room. The team discovered that people with low first hands had a left-ward gaze, while with increased value, the direction of their gaze moved to the right.

Unfortunately for keen blackjack players, the tell isn’t of much practical use: the degree of movement of the eye ranges from 0.1 degrees to 0.4 degrees off-centre which is incredibly hard to detect with the naked eye. Psychology applicants should consider how research can be extrapolated to inform new experiments, as well as how psychological research can be practically applied outside of research settings.

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