You will know this feeling listening to a radio broadcast and knowing, just knowing, whether what is being said is being read or just ‘said’ without script or rehearsal. Leaving aside the differences in vocabulary, grammar and phrasing between written and spoken language, there is still a difference. This shows when even very well written dialogue is read or memorized rather than delivered by a great actor. I have often wondered about the unknown ingredient, is it a lack of polish or signs of emotional involvement or the ability to ‘hear the wheels’ of the mind churn around, that makes something sound spontaneous.
A recent paper by Engel and Keller in Frontiers in Psychology (see citation) has looked at whether and how experienced musicians can tell the difference between improvised jazz and good imitations of it. Here is the abstract:
The ability to evaluate spontaneity in human behavior is called upon in the aesthetic appreciation of dramatic arts and music. The current study addresses the behavioral and brain mechanisms that mediate the perception of spontaneity in music performance. In a fMRI experiment, 22 jazz musicians listened to piano melodies and judged whether they were improvised or imitated. Judgment accuracy (mean 55%; range 44-65%), which was low but above chance, was positively correlated with musical experience and empathy. Analysis of listeners hemodynamic responses revealed that amygdala activation was stronger for improvisations than imitations. This activation correlated with the variability of performance timing and intensity (loudness) in the melodies, suggesting that the amygdala is involved in the detection of behavioral uncertainty. An analysis based on the subjective classification of melodies according to listeners judgments revealed that a network including the pre-supplementary motor area, frontal operculum, and anterior insula was most strongly activated for melodies judged to be improvised. This may reflect the increased engagement of an action simulation network when melodic predictions are rendered challenging due to perceived instability in the performers actions. Taken together, our results suggest that, while certain brain regions in skilled individuals may be generally sensitive to objective cues to spontaneity in human behavior, the ability to evaluate spontaneity accurately depends upon whether an individuals action-related experience and perspective taking skills enable faithful internal simulation of the given behavior.
What the authors have to say about the amygdala is interesting. Another nail in the coffin for the idea that the amygdala is all, and only, about fear.
Classical views describing amygdala involvement in threat detection, fear conditioning, and the processing of negatively valenced emotional stimuli have recently been supplemented by accounts of amygdala function in the context of non-aversive events. These accounts range from those postulating general functions, such as the detection and appraisal of stimuli that are relevant to an individual’s basic, as well as social, goals and needs, to these identifying more specific functions. The latter are related to findings that amygdala responses are modulated by stimulus ambiguity, novelty, temporal unpredictability, and in music- the violation of listeners’ harmonic expectancies. In functional terms, the amygdala maybe involved in heightening vigilance and attention in response to ambiguity in external signals.
So coming back to my original puzzle, I still believe that lack of polish and signs of emotional involvement are important in knowing when someone is not reading. The third guess which seemed a bit lame has become much more convincing in light of this research it maybe that by stimulation we can hear the wheels of the mind churning.
Engel, A., & Keller, P. (2011). The Perception of Musical Spontaneity in Improvised and Imitated Jazz Performances Frontiers in Psychology, 2 DOI: 10.3389/fpsyg.2011.00083