Psychology › Brain & biology › Brain regions and localization of function
Brain imaging: EEG, PET and fMRI
EEG 1924; fMRI early 1990s· Concept
Well replicatedStrong, repeated evidence.
Tools that record the living brain at work: EEG reads electrical waves, PET tracks injected tracers, fMRI tracks blood flow.
See it on the Psychology map →What it says
German psychiatrist Hans Berger recorded the first human EEG in 1924 with electrodes on the scalp: precise to the millisecond, blurry about location. PET, developed in the 1970s, follows a mildly radioactive tracer to show where the brain uses sugar or where a drug binds. fMRI, from 1990–1992 (Seiji Ogawa found its blood-oxygen signal), detects extra oxygen-rich blood flowing to busy areas, pinpointing location to a few millimeters but lagging seconds behind. The colorful 'lit-up' pictures are statistical maps, not photographs.
Why it matters
Researchers could finally watch healthy brains think, rather than study damage after injury or death. Imaging now also guides epilepsy surgery and dementia diagnosis.
The evidence
Status: well replicated as a set of tools, used in tens of thousands of studies. But a 2020 Duke analysis found common task-fMRI measures poorly reliable when the same person is rescanned.
Open questions
How much a scan can say about one individual: a 2022 analysis found reliable links between brain features and traits like intelligence or mood need thousands of participants.
Connections (2)
▸Brain imaging: EEG, PET and fMRI is vulnerable to P-hacking and 'false-positive psychology'Well replicated
The connection
An fMRI scan tests tens of thousands of tiny brain units, called voxels, at once, so some will 'light up' by chance unless the statistics correct for it. Flexible analysis choices, small samples and selective reporting add more false positives. Brain imaging became an early, vivid warning case of the p-hacking problem.
Who showed it and when
2009: Craig Bennett's team found 'activity' in a dead salmon shown photos, and Edward Vul flagged 'voodoo correlations'. 2016: Anders Eklund's team in Sweden tested common analysis software.
The evidence
Those papers are published and easy to check; Eklund's team found standard methods could give false-positive rates up to 70% instead of the intended 5%.
Open questions
How many published imaging findings are false; estimates vary, and the field has since moved to larger samples, preregistration and shared data.
▸Brain imaging: EEG, PET and fMRI maps activity in Brain regions and localization of functionWell replicated
The connection
Before imaging, a region's job was inferred from injuries or autopsies. PET and fMRI let researchers watch healthy brains as people read, remember or decide, showing which areas work harder. That confirmed classic regions like Broca's area, found new ones like a patch specialized for faces, and showed that tasks recruit networks of regions.
Who showed it and when
Washington University in St. Louis led early PET mapping in the 1980s (Marcus Raichle, Michael Posner); Nancy Kanwisher's team in Cambridge, Massachusetts, described the 'fusiform face area' in 1997.
The evidence
Results repeat across labs and match lesion and stimulation evidence; large shared datasets like the Human Connectome Project allow independent checks.
Open questions
Activity is not proof a region causes a function; 'reverse inference', reading a mental state from which area lit up, is often unreliable.