In poker, a player can gain an advantage if she can detect tells, subtle behaviors from other players that communicate the strength (or weakness) of their hands. Tells are not always reliable (e.g., clumsiness could be misinterpreted as anxiety about a bad hand) so veteran players use them cautiously.
In fact, it is hard to find a behavior that, on its own, predicts what someone is thinking. It is almost always a collection of behaviors, persistent across time and situations, that suggest a psychological state. Wouldn’t you be more convinced that someone loved you if they expressed this emotion in 100 ways instead of one? Individual behaviors are rarely good tells.
Yet neuroscience commentators often claim to write about neural tells: individual neural measurements that are highly reliable indicators of psychological variables like love (e.g., the oxytocin myth). But neural tells are Procrustean beds because, as I explain below, they ought to be significantly less reliable than behavioral tells.
Levels of Analysis
Psychological variables, like love, cannot be measured directly (after all, what is love?). Scientists simply search for tells, measurable variables that ought to correlate with the psychological variable. For example, the number of poems a couple write each other can be a tell of the strength of their love. But the correlation between the psychological variable and the tell weakens when these two variables exist in different levels of analysis.
For instance, brain activity can be measured at multiple levels of analysis. At an electro-physiological level, scientists can measure voltage changes that follow neural activity. At a hemodynamic level, scientists can measure oxygen level changes in the blood around active neurons. In this example, brain activity is examined at one of two levels of analysis.
A scientist can mix levels of analysis. She can hypothesize about electrophysiology but measure hemodynamic activity as a tell. For example, she can use functional magnetic resonance imaging (fMRI) to measure oxygen concentration changes in the brain’s blood, but hypothesize that these changes reflect fluctuations in the brain’s electrical activity.
Luckily for her, electrical and hemodynamic activity are highly correlated (Logothetis & Wandell, 2004): the presence of one very often indicates the presence of the other. In turn, hemodynamic activity is a great tell for neural activity. Unfortunately, this is not the case in most situations that involve hypotheses and variables that mix levels of analysis.
…Make Tells Less Reliable
Variables often lack one-to-one relationships across levels of analysis. For example, love (psychological level) cannot be mapped to a single action (behavioral level). No behavior by a person indicates, always and exclusively, that she feels in love. Using this logic, neuroscience commentators should not expect to find highly reliable neural tells.
Most likely, it is a collection of neural measurements that should predict behavior and psychological variables. A variable in a higher level of analysis is almost always comprised of multiple variables in a lower level of analysis. So even a single emotion like love ought to have a complicated neural basis that is constituted by more than one neural measurement.
- Neuroscience commentators claim to write about neural tells, individual neural measurements that are highly reliable indicators of psychological variables
- But variable relationships across levels of analysis (behavioral to psychological, neural to psychological) are not one-to-one, making neural tells unlikely to exist
- More often than not, it should be a collection of neural measurements that, together, predict psychological variables