One more bioassay: this time less than 1tbsp of ground Acacia confusa root bark and less than 1/2tbsp of Syrian rue seeds. The simplest preparation possible: the rue seeds ground and combined with the bark, steeped in 3 washes of boiling water, filtered, the residual plant material discarded. The liquid slowly consumed over the course of an hour, resulting in a distinctive two-part trip.
For the first 1.5 hours, a relatively soft trance with all the senses heightened, in particular, strong inner visualizations of muscular postures, combined with spontaneous investigative body movements (trying to feel my body better). Very refreshing.
Then I felt pretty much back to baseline and somewhat hungry. So I ate a bowl of fava bean soup. This resulted in a sharp surge of intoxication, and for the subsequent half-hour, I was propelled into the psychedelic realm familiar from my previous higher-dose acacia trips. This time, it was much more under control, since the dose was smaller and I was more familiar with the effects. In particular, I could maintain my identity throughout and could ground myself firmly for a few seconds every now and then, before returning to the visionary realm. Still, some aspects of the acacia-induced trance are quite overwhelming, even in smaller doses: there was a feeling of being controlled, or connected to something larger than "myself", a sense of myriads of tentacles probing my shoulders, etc. Bright hyper-kinetic "high-tech" colorful geometric visions (equalizer bands and the likes). There was a feeling of strong alertness after returning to the ordinary consciousness. I then took a walk in a park, cooling off.
There have been anecdotal reports that a light meal in the course of ayahuasca trips can provoke a surge in trip intensity. My experience seems to conform with this observation.