Great question ! >*You asked: "Why is it that someone can say a word completely fluently, but then when asked to repeat that word, they sometimes stutter?"* Different stuttering theories provide distinct explanations for this phenomenon. According to the Variable Release Threshold (VRT) mechanism: **Genetic and neurological abnormalities/weaknesses** * may cause speakers to become hypersensitive to cues that alert them to potential upcoming difficulty, and/or lead to misinterpretation of auditory feedback, thus distorting speakers’ perceptions of their performances. * negative experiences may stem from impairments/illnesses that prevent the stutterer from attaining a high quality of speech production. For example, the speaker may be unable to clearly pronounce words due a sore throat or blocked nose * may undermine the speaker’s confidence in his ability to speak well enough and may thus predispose to stuttering but their contribution is much less important than that of the speaker’s understandings and beliefs: stuttering is primarily a cognitive disorder **On a Moment to moment basis, or word-to-word basis - the execution threshold fluctuates in response to stimuli: (**e.g., based on the speaker's perception of the importance and accuracy required for their speech.**)** **Prior to speech production:** Novel or unexpected stimuli cause an initial phasic spike in synaptic dopamine levels – enabling us to orientate our attention towards those stimuli in order to identify and evaluate them Stimuli such as: E.g., Clumsiness of articulation; negative listener reactions; stuttering anticipation. These conditioned stimuli make us feel we aren’t speaking well/clearly enough to elicit the desired positive listener response. **Evaluation process:** Our brain evaluates the speech plan (stimulus) - based on the entirety of one’s prior learning and experience – of speaking about similar things, using similar language, in similar situations, with similar people. All these experiences summed together and (each segment of) the speech plan receives either a positive, negative or neutral evaluation. **Positive evaluatoin:** Net positive evaluation: If there are more positive evaluations than negative evaluations - the release threshold goes down The activation of our past memories (of speaking similar things in similar situations) are a series of responses to the speech plan (reinforcers/punishers). Some responses are associated with pleasurable outcomes, whereas others with painful outcomes In this way the speaker may become excessively perfectionistic and sensitized to their speech that doesn’t conform to their ideal. **Negative evaluation:** If a stimulus is evaluated as punishing, the initial spike in synaptic dopamine will be reversed which inhibits approach behaviours toward that anticipated punishment. It is characterized by a lack of faith in their ability to speak: leading the speaker to perceive that their speech is not good enough - which may then cause them to mistrust their (feed-forward) motor-programs and instead to rely excessively on auditory feedback. **Negative conditioned response (or unhelpful behavior):** a rise in the release threshold for muscle movements and consequent difficulty initiating actions (Symptoms range from depression to full-blown freeze response) Primary block: Which is our body’s way of trying to prevent us from making speech errors i.e., perceived conflict between what we plan to say and (anticipate) actually saying. I've condensed over 1,000 pages of research papers into a 3-page summary, which you can access on my [google drive](https://drive.google.com/file/d/1eJXkd9Qny-hl7WpbotQZ1PTQO0Od987O/view?usp=sharing) if you're interested.