Why does turning 'Diffuse Reflection' to OFF then remove my internal shadows?

[brokentoothpix]

I have unwanted color coming from the diffuse channel (?) of one object onto other objects in my scene. (torso -> arms)

In the Arnold Tag under the Custom Parameters tab, when I uncheck 'Diffuse Reflection' I no longer get unwanted diffusion, although I now lose what appears to be my internal shadows? (torso/collar)

Why is my diffuse channel reflecting color? How can I keep my shadows without having this diffusion problem?

Any suggestions or insight is appreciated. I'm stuck.

[brokentoothpix · Accepted solution]

Thankfully this was a simple thing. If you're having the same issue:

by using an Ambient Occulsion node in my 'Torso' shader, I was able to drive shadows while keeping 'Diffuse Reflections' off

1. Set output of AO node to A input of composite node where B input is a flat node.

2. Set A multiply over B.

3. Set output of composite node to color input of standard surface.