How Inner Speech and Talking Out Loud Affect Your Eyes Differently: New Pupil Study

Scientists have discovered that the way you talk to yourself—whether silently in your head or out loud—changes your pupils in measurably different ways. A new study published in the Journal of Cognitive Neuroscience found that inner speech causes pupil dilation that peaks later and lasts longer compared to external speech. The research, led by Thomas Hinault at the French National Centre for Scientific Research, used eye-tracking technology to monitor 22 participants as they performed tasks involving silent and spoken word generation. Understanding these physiological differences matters because it sheds light on how the brain manages language and attention, with potential implications for diagnosing conditions like schizophrenia, where inner speech is disrupted. The findings suggest that our eyes could serve as a window into the covert mental processes that shape thought. As researchers refine these methods, we may soon be able to read the mind's silent voice through the eyes.