:) Firstly, I'm still not sure what you mean by mental. Two things come to my mind: psychological (dealing with the mind, the perception we create of ourselves etc) and neurobiological (dealing with the working of the brain, what "lights up"). I'm not sure where you draw the line, my guess is that by mental you're referring to what I would call psychological. This is neither here nor there, just wanting you to know where I'm coming from. Anyway, it's suggested that because in your case stuttering was not alleviated by a reduction in fear, developing a positive attitude towards communication and slowing speech but is alleviated by speaking in isolation and certain drugs (not sure if prescription or recreational) then your stuttering must be mental (psychological) in nature. Another way to write this (for simplicity) is: Given no response in A, B, or C, and response in D and E, the answer must be (the common feature between D and E). This seems reasonable. Except for the fact that there might be (and most certainly are) other variables not considered here (for instance, your familiarity with the content material, your familiarity with your communication partner, the average length of words, how easy it is to conceptualize the words, the environment you're communicating in, and so on). Thus, it might not be D/E, but actually F. Furthermore, A (fear), B (attitude), C (slow speech), D (solo speech) and E ("drugs") are not independent of each other -- they will all affect one another (even the ones that don't affect stuttering in your case -- e.g. you probably still have a bit of apprehension about stuttering in some situations, like a job interview). Thus, it might not be D/E but actually D/E in the presence of A/B/E/F. These are highly nuanced points that researchers spend a lot of time thinking about. But they're important to consider because you don't stutter for vastly different reasons than me, or anyone with with developmental stuttering. The phenomenon of stuttering is a group phenomenon. The experience of stuttering is highly personal (you and I react differently to the presence of stuttering). You're probably more interested in the experience of stuttering -- how you react to your stuttering. You probably don't care how I react to my stuttering. Nor should you--it has no significance on your life at all. But I'm interested in the phenomenon of stuttering--why does stuttering occur. In that light, I have a couple questions. (In none of these do I doubt your experience, i'm literally just wondering): - How do you know you're not afraid of stuttering? - How do you know you have a positive attitude about communication? - Are you certain you're not stuttering when you're alone, or are you paying less attention to your speech resulting in a lack of awareness of stuttering? - Are you certain your impaired judgment from ingestion of mind-altering substances gives you a reliable metric to judge how successful the drug was? I actually expect that you do stutter when you're alone. I do. But my stutters are very short, rapid single sound repetitions. Other researchers have noticed the same thing in other stutterers. I would venture a guess that even while speaking in isolation stutterers have more stutters than nonstutterers (however there are no empirical data for this, it's just my idea). Indicating that there is a very basic difference in the way the brains of stutterers control speech. My opinion is that this subtle change the way our brains controls speech is mediated by any number of things (like drugs, people, environment). These can increase or decrease the likelihood of a stutter emerging. So, to bring it back, you're honing in on what your stutter is sensitive to, not what causes it. Hopefully that wasn't too confusing.