The Decision Begins Before the Response - Musical Familiarity and Evidence Accumulation

You are walking and see something long on the ground.

Your body steps back.

Your heart speeds up.

For a few moments:

snake.

Then more information arrives.

It is not moving.

The texture looks like wood.

“Oh… it was just a branch.”

What is interesting is that the Body-Territory had already changed before it could explain what it was seeing.

Joseph LeDoux spent decades studying defensive circuits and today makes an important distinction: the amygdala participates in rapid systems of threat detection and defensive response, but it should not simply be treated as the “fear center.” The conscious experience of fear involves broader cognitive processes.

This leaves us with a question:

How much can happen before we are able to say what happened?

And perhaps music offers one of the most elegant ways to investigate this.

Before “I know it,” perhaps there is “I have lived this before”

A song begins.

One note.

Another.

You still do not remember the title.

But something changes.

Then comes:

“I have lived this before.”

Another note.

“I think I know what comes next.”

Finally:

“I know this song.”

This is precisely the transition investigated by Jared R. Girard, Aaron Bishop, and Cameron D. Hassall in Song Familiarity Relies on Evidence Accumulation, published in 2026 in Psychophysiology.

Participants listened to melodies and pressed a button as soon as one began to feel familiar.

EEG revealed a prominent central-parietal positivity — CPP aligned with the decision. In an exploratory analysis, the authors also found note-related activity that increased shortly before the familiarity decision.

In other words:

the button did not appear to be the beginning of the story.

Something had already been building before it.

P300: “Something here matters”

Decades of EEG research have already shown that the brain produces later event-related potentials when something relevant, unexpected, or important occurs.

One of the best known is the P300.

Its name can be misleading: it does not necessarily occur at exactly 300 ms. It refers to a family of later positive potentials.

In simplified terms, researchers often distinguish:

P3a: more closely related to novelty, salience, and attentional orientation.

P3b: more closely related to task relevance, categorization, memory, and context updating.

As a teaching metaphor:

P3a: “Wait. Something changed.”

P3b: “This matters to what I am doing, and it changes my model of the situation.”

This does not mean that the brain literally speaks these sentences.

But it helps us visualize something essential:

before our verbal explanation, an event may already have acquired relevance.

The present changes what will be perceived next

In BrainLatam’s 5D Consciousness hypothesis:

Consciousness is the movement that perceives itself as Being within the metabolism produced.

This leads to a different reading of music.

Each Perceived note does not simply add information.

It participates in transforming the Body-Territory that will perceive the next note.

So:

note

→ transformation

new note

→ encounters a different state

new transformation

→ expectation

familiarity

Perhaps, therefore:

evidence does not merely accumulate. It successively transforms the one who receives it.

The past does not have to be consulted only as a stored file.

It already participates in the Body-Territory receiving the present.

P300 and CPP are not two mandatory steps

Here we need caution.

We cannot say:

first P300, then CPP.

CPP and P300/P3b share several electrophysiological properties. CPP is closely related to the P300 family and became especially important in decision research because it can show a gradual build-up toward a decision threshold, tracking evidence strength and response timing.

A useful way to think about them is:

P300/P3b helps investigate relevance, categorization, and context updating.

CPP is especially useful for observing how evidence may be integrated toward a decision.

They are not rigid sequential stages.

They are electrophysiological windows onto partially overlapping processes.

Each note may change the context of the next

This makes Girard’s study even more interesting.

The participant does not receive the entire song instantaneously.

They receive:

note;

note;

note;

note.

Each event changes the context.

The fourth note may therefore have a different meaning because the first three have already occurred.

The authors themselves raise an important possibility: a song may begin to feel familiar when its notes become more predictable.

But they also acknowledge that the experiment was not designed to fully separate prediction from attention and other processes.

So:

“I have lived this before” may begin to transform into “I think I know what comes next.”

Attention changes the speed of the decision

Another finding makes this story even more interesting.

In 2024, Morrow and colleagues showed that when attention was correctly directed toward relevant information, the CPP displayed a steeper build-up rate.

This allows us to distinguish between:

not possessing information

and

being unable to recruit it at the moment it is needed.

In the 5D hypothesis:

an attentional shift may not erase what was lived; it may simply make it harder for that experience to participate in the present decision.

And this leads to a new possibility.

What if the decision also involves “which Self knows how to do this?”

Imagine an experienced goalkeeper.

They perceive the attacker’s posture.

Foot position.

Distance.

Recent history.

Perhaps these cues are not merely producing:

“left or right?”

Perhaps they are making recruitable an entire functional configuration that has already lived through hundreds of similar situations.

Attention.

Proprioception.

Prediction.

Motor programs.

Muscle tone.

Action possibilities.

In BrainLatam’s vocabulary:

a Tensional Self.

The decision may then involve something functionally similar to:

“this Self already knows.”

Rock: “I already know”

We call Rock a configuration of high readiness, with strong sensorimotor, somatosensory, proprioceptive, and highly trained automated participation.

Rock is not a brain region.

It is a functional metaphor.

Given the right cues:

“I already know.”

Not necessarily as a conscious sentence.

The Body-Territory makes available again a configuration that has already operated in that situation.

Musical recognition may contain something similar.

Each note progressively makes more recruitable:

the Self that has already lived that movement.

But the “I already know” Self can be wrong

Déjà entendu, the auditory analog of déjà vu, shows why caution is necessary.

In 2025, McNeely-White and Anne Cleary showed that people experiencing déjà entendu more often felt that they knew what would happen next musically.

But they did not actually predict better.

This is extraordinarily important.

familiarity can generate a feeling of prediction without generating accurate prediction.

The Tensional Self that says “I already know” can also be wrong.

At that point, it may become necessary to leave Rock and recruit:

Scissors — “I need to think.”

We provisionally call this change a Tensional Transition:

the shift between functional configurations of the Body-Territory when evidence makes one configuration more or less appropriate to the present.

This is a BrainLatam hypothesis — not a demonstrated function of CPP.

CPP is not consciousness

Nor should CPP be transformed into a marker of consciousness.

The same caution applies to P3b.

No-report experiments have shown that participants can consciously perceive stimuli without displaying the robust P3b often found when they are required to report what they perceived.

This suggests that P3b is strongly related to post-perceptual processing, categorization, and report, rather than simply to the existence of conscious experience itself.

So:

P300 is not consciousness.

CPP is not consciousness.

CPP does not switch the Self.

But both can help us see something fascinating:

between what happens and what we are finally able to say, a great deal may already have happened.

The words may come after the decision

Patients with epilepsy have provided another extraordinary window into this problem.

In 2024, Sabina Gherman and colleagues recorded intracranial activity while patients made perceptual decisions.

In one condition, twelve participants had to form the choice, wait through a random delay, and only then verbally report the answer.

Even so, distributed dynamics compatible with evidence accumulation were still observed.

This demonstrates a fundamental separation:

forming a decision and saying the decision are not necessarily the same event.

Perhaps “I chose” is only the visible part

Return to the music.

First note.

Something changes.

Second.

Something feels familiar.

Third.

“I have lived this before.”

Fourth.

“I think I know what comes next.”

Then:

“I know this song.”

And finally:

the button.

Perhaps the response is only the moment we can measure most easily.

The trajectory began earlier.

The major contribution of Girard, Bishop, and Hassall is precisely to make this trajectory visible using EEG and an everyday experience such as music. The study used BrainVision Recorder and a BrainAmp DC amplifier from Brain Products, once again showing the value of high temporal resolution for studying decisions that unfold across hundreds of milliseconds and seconds.

The BrainLatam hypothesis goes one step further:

perhaps some decisions are not only about which response to produce, but about which configuration of the Body-Territory becomes recruitable in order to produce that response.

In that case, familiarity would not simply mean:

“I found this song in memory.”

It could mean:

“the present movement made possible again the Self that has already lived this.”

And that leads to the question that opens the next blog:

when we finally say “I chose,” how much of the choice had already happened before that Self was able to tell the story?

References

Girard, J. R., Bishop, A., & Hassall, C. D. (2026). Song Familiarity Relies on Evidence Accumulation. Psychophysiology, 63(8), e70370. DOI: 10.1111/psyp.70370.

Gherman, S., Markowitz, N., Tostaeva, G., et al. (2024). Intracranial electroencephalography reveals effector-independent evidence accumulation dynamics in multiple human brain regions. Nature Human Behaviour, 8, 758–770. DOI: 10.1038/s41562-024-01824-9.

Morrow, A., Pilipenko, A., Turkovich, E., Sankaran, S., & Samaha, J. (2024). Endogenous Attention Affects Decision-related Neural Activity but Not Afferent Visual Responses. Journal of Cognitive Neuroscience, 36(11), 2481–2494. DOI: 10.1162/jocn_a_02239.

McNeely-White, K. L., & Cleary, A. M. (2025). Illusory feelings of prediction during déjà entendu: An auditory analog to illusory feelings of prediction during déjà vu. Memory & Cognition, 53(8), 2375–2393. DOI: 10.3758/s13421-025-01716-x.

Polich, J. (2007). Updating P300: An integrative theory of P3a and P3b. Clinical Neurophysiology, 118(10), 2128–2148. DOI: 10.1016/j.clinph.2007.04.019.

Cohen, M. A., Ortego, K., Kyroudis, A., & Pitts, M. (2020). Distinguishing the Neural Correlates of Perceptual Awareness and Postperceptual Processing. Journal of Neuroscience, 40, 4925–4935.

LeDoux, J. E. (2020). Thoughtful feelings. Current Biology, 30, R619–R623. DOI: 10.1016/j.cub.2020.04.012.