Despite the small effect size, dissociating the total ACD into its respiratory (RSA) and non-respiratory (ACD) components showed that decreased RSA and a steeper rise in ACD are associated with visual detection.

While the amplitude of the sine wave in our method corresponds to the amount of RSA, the vertical offset represents the respiratory-phase-independent modulation of the heart rate. In our case, the positive offset is ACD (left). We see that RSA and ACD-based modulations do not co-fluctuate (right).

So, can the ACD only be caused by this respiratory phase-alignment? We saw that there is a pattern of cardiac deceleration during both exhalation and inhalation, so probably not.
But how to properly quantify a respiratory-phase-independent deceleration?

Interestingly, our subjects aligned their respiratory phase to exhalation (breathing out) during stimulus anticipation, which in itself supports cardiac deceleration due to RSA. And the amount of RSA in the anticipation window was correlated with the amount of ACD at the between-subject level.

We present a simple sinusoidal modeling approach to estimate trial-averaged RSA amplitudes for each subject during the anticipation window of our visual perception task (threshold-level visual stimulus detection).

...but this inevitably leads to contamination from permanent heart rate oscillations driven by respiration (Respiratory Sinus Arrhythmia - RSA, or respiratory HRV).

So, we need to account for this to get more accurate estimates of short-term heart rate modulations such as the ACD.

I'm extremely honoured to receive the Young Scientist Award at the MindBrainBody Symposium this year! 🎊

Big thanks to @mpicbs.bsky.social and everyone involved in the organization!!

Already looking forward to share results from my upcoming experiments in the next edition of #MBBS

#MBBS25

[9/9]: Many thanks to everyone who made this work possible! 🧠
@primatenzentrum.bsky.social
@unigoettingen.bsky.social

[7/9]

Finally, we estimated that 24.4% of all perceptual switch events in Task 1 are induced by saccades, hence not spontaneous.

[6/9]

Comparing PSLs from our implementation of Hesse & Tsao's paradigm (Task 1) against the continuous binocular rivalry task wherein both external factors are absent (Task 2), we estimated time windows that we can exclude if we want to discard "induced" switches.

[5/9]

If the FPs jump at t=0 but the subject only fixates to the center (Task 3); there is a small change in perceptual switch latency (PSL) distributions.

If the subject performs saccades while FPs remain stable (Task 4), distribution changes a lot.
Saccades induce time-locked switches!

[4/9]

We implemented a two-factorial design to test the influence of the two external factors ("visual appearance of the new fixation points" and "requirement for a saccade to follow them") on the timing of perceptual switches.

[2/9]

In this elegant paradigm; each rivaling stimulus has its own fixation point (FP) that "jumps" every few seconds, and subjects follow the FP of the perceived object with their eyes.

The paradigm is utilized to show how the conscious and subconscious content is encoded together in macaque IT.