Stammering and post-traumatic stress – some food for thought

An essay from researcher Paul Brocklehurst, who argues that stammering and post-traumatic stress may create a vicious circle, and proposes modifications to therapy and self-help approaches.

A man, smiling
Paul Brocklehurst

If you were to ask a selection of people who stammer how their stammering first came about, it is likely that a proportion of them will attribute its onset to a psychologically traumatic event such as a death in the family, the arrival of a sibling or having to speak in front of the school class. 

Although such attributions sound superficially plausible, in recent years they have tended to be discounted because, despite researchers' best efforts, there is a lack of any strong reliable evidence to support them.

As a researcher myself, I have never been convinced that this lack of reliable evidence for a causal link between stammering and trauma constitutes a valid reason to dismiss such a possibility. After all, the lack may well simply reflect the fact that this is a difficult area to research, and it is noteworthy that there is an equal lack of reliable evidence that there is not a causal link between stammering and trauma. So, until such evidence can be produced either way, this remains an open question.

I also think that the current focus on the importance of genetic factors in the onset of stammering may have contributed to a tendency for researchers and clinicians to underestimate the importance of life-events in its onset.

Whatever the case (see footnote 1), the existence in the world of many pairs of identical twins where only one of the two twins stammers (Bloodstein & Bernstein Ratner, 2008; Ooki, 2005), despite the fact that identical twins share identical genes1, supports the theory that only a predisposition to stammering is usually inherited, and whether or not that predisposition then manifests as stammering, and whether or not that stammering then persists almost certainly depends on environmental factors – in other words, on things that have happened to us during our lives. And trauma may sometimes be one of those things.

Whether or not that predisposition manifests as stammering, and whether or not that stammering persists almost certainly depends on environmental factors, which may sometimes include trauma.

Researchers are more likely to search in the right places for evidence of a causal relationship between stammering and trauma if they already have a plausible explanation for why such a relationship is likely to exist. So in this essay I shall try to provide such an explanation. 

To do so, I will focus on two questions: 

  1. Is it possible that post-traumatic stress can play a causal role in the onset and/or persistence of stammering?
  2. Is it possible that experiences of stammering can lead to post-traumatic stress responses?

I will argue that the answer to both of these questions is 'Yes'.

I will also discuss why, from a theoretical perspective, severe stammering is more likely to lead to post-traumatic stress than mild stammering, and how post-traumatic stress may then play a role in the persistence of stammering.

Finally, I will discuss some implications for therapy and self-help that arise in cases where stammering and post-traumatic stress do indeed co-exist.

Post-traumatic stress & stammering

What is post-traumatic stress?

Essentially, post-traumatic stress is a stress response that recurs when a person is reminded of a previous traumatic event. By 'stress response', I mean a physiological response that, from an evolutionary perspective, may have helped our ancestors to escape from and survive life-threatening events.  

Such responses include 'flight', 'fight' and 'freeze'. Flight and fight responses may involve, amongst other things, release of adrenaline, increase in heart-rate, and an increased blood supply to the muscles of the arms and legs. In contrast, Freeze response may result in vasoconstriction (narrowing of blood vessels), greatly reduced heart rate, cessation of breathing, and temporary full-body paralysis – all of which contribute to making the person appear dead – which may be especially useful in life-threatening situations where flight or fight responses would be of no avail.

It's important to distinguish between 'post-traumatic stress' and 'Post-Traumatic Stress Disorder' (PTSD), as they are not the same thing. Although not a pleasant experience, post-traumatic stress is, in itself, a natural and healthy reaction to life threatening events. It can help us to remember, recognise and to successfully avoid or escape from future similar dangerous or life-threatening situations. Consequently, it serves to increase our overall chances of survival. It only becomes a 'disorder' in cases where its symptoms become overwhelming and unhelpful such that their net effect is to reduce our ability to cope with day to day life.

Might post-traumatic stress lead to stammered speech?

Is it possible that post-traumatic stress responses may lead to the production of stammered disfluencies?

When someone is experiencing traumatic stress, and their body goes into fight/flight (or freeze) mode, blood is diverted away from the parts of the brain responsible for language and speech production, and consequently, their capacity to formulate language and to initiate speech is significantly reduced (Porges, 2011). At such times, initiation of speech is more difficult, and any speech that is produced is likely to be more error-prone and more clumsy than normal. Also, the tone of the speaker's voice is likely to be adversely affected, due to stress-related changes in muscle tension in the vocal folds (Perkins, Kent, & Curlee, 1991). 

Individuals whose speech and language abilities are less developed or less stable (such as children, especially those with a family history of stammering or other related disorders) are particularly likely to be affected in these ways. If, when experiencing such difficulties, a speaker then starts to use force in order to speak, he is at increased risk of producing symptoms of stammering (Bloodstein, 1975; Brocklehurst, Lickley, & Corley, 2013). And if this happens on a regular basis, then it could quite plausibly contribute to the tendency for such symptoms to persist.

Blood is diverted away from the parts of the brain responsible for language and speech production.

Might stammering experiences lead to post-traumatic stress?

Is it possible that experiences associated with stammering can lead to the production of post-traumatic stress responses?

Generally speaking, when we think of the sort of experiences likely to result in post-traumatic stress, we tend to think of extreme, life-threatening events; and one might presume that experiences of stammering, even severe stammering, are just not that serious. However, a key issue here that we need to remember is that stammering – and in particular, severe stammering – frequently leads to communication failure. 

This is especially significant because humans are social animals, and the ability to successfully communicate is one of the key skills that we need in order to integrate socially and hence also to survive and thrive. Consequently, experiences that suggest to us that we are failing to communicate successfully are indeed likely to be highly traumatic, because such experiences are likely to lead to social rejection, which historically at least would have put our survival at risk.

Stammering – and in particular, severe stammering – frequently leads to communication failure. This is especially significant because humans are social animals.

I would suggest that, initially at least, it's not the stammering itself, but rather it is the negative reactions of the people that we try to speak to that are likely to traumatise us. In addition to signalling to us that we are being misunderstood, such reactions may also signal to us that we are being perceived in a negative light - as unintelligent, mentally unstable, or not telling the truth. 

If you have a severe stammer, it is likely that you will experience such negative listener reactions and associated social rejection on a daily basis. Indeed, perhaps it is because such negative listener reactions often do happen on a daily basis that we may be inclined to under-estimate how traumatising they can be.

In addition to all of this, for people who stammer severely, a further traumatic, stress-inducing experience of stammering is that of time pressure. Essentially, we feel time pressure in many situations, because we know from experience that there is a limited window of opportunity in which to speak, and if it takes us too long to get our words out, we are likely to miss that window of opportunity and fail to get our message across. 

For people who stammer severely, running out of time is likely to be an everyday experience; as are experiences of people putting the phone down on you; people becoming impatient or getting annoyed (because they are in a hurry); and people losing interest and ceasing to listen. Severe stammerers can often vividly recall such experiences, even many years later.

A vicious circle

If traumatic stress can lead to stammering, and stammering can lead to traumatic stress, then we have the ingredients necessary for the development of a vicious circle. I find this really interesting, because one of the properties of vicious circles is that they are self-sustaining. Consequently, if this sort of vicious circle does become established, it could help explain why a stammer is likely to continue to persist quite irrespective of whether or not the factors that originally caused it still exist.

So, having accumulated many experiences of negative listener reactions when speaking, we may find ourselves unable to speak fluently because every time we enter a speaking situation, we produce a post-traumatic stress response that deactivates our speech and language production system.

A diagram featuring the words 'Traumatic-stress' at the top and 'Stammering' below it, with arrows forming a loop between them
Figure: Stammering and traumatic stress may form a vicious circle

Empirical evidence?

So much for the theory; but is there any empirical evidence that trauma can lead to stammering and/or its persistence?

The short answer to this question is that there is some evidence, but it is not very reliable.

There are a lot of published case-studies describing late-onset stammering following trauma. However, most of these studies are of cases where there was also some physical trauma as well, such as traumatic brain injury (e.g. Bijleveld, 2015). So it’s impossible to be certain to what extent the traumatic memory played a role independent of the physical damage.

Similarly, many people who stammer recount stories of how their stammering started when they were a child, after a (psychologically) traumatic experience. Unfortunately, however, it is impossible to know to what extent such traumatic experiences really played a role in the onset of their stammering, as it is quite possible that the two events are unrelated despite their proximity. 

Human beings have a natural tendency to ascribe causal relationships to major events that happen in close succession, even when no causal relationship exists (Buehner, 2014). Nevertheless, one early traumatic memory that people who stammer frequently associate with the onset of their stammering is of having to speak/read aloud in front of the class. 

The consistent regularity of such self-reports among people who stammer does suggest to me that traumatic memories associated with this type of experience may well contribute to the onset of stammering, in older children who are already at risk of stammering, in as much as they are genetically (or otherwise) predisposed to the condition, and/or to the persistence of stammering in children who already show symptoms of stammering.

One early traumatic memory that people  frequently associate with the onset of their stammering is of having to speak/read aloud in front of the class.

Some implications for therapy and self-help

In recent years there has been a marked shift in the approach of speech therapy for stammering away from traditional fluency-shaping approaches and towards approaches embedded in the social model of disability. Key features of this new approach are an emphasis on the need for society to adapt and accommodate stammering, and a tendency for therapy to focus more on self-esteem issues than on promoting greater fluency.

Although, overall, I think this shift has been beneficial to the majority of people who stammer, I perceive that it has not been so beneficial to people whose stammering is severe and whose speech-rate is substantially slower than that of their interlocutors, and for whom time pressure and negative listener reactions may be a major source of traumatic stress. 

Consequently I cannot help but question the usefulness for people whose stammering is severe of some current assumptions that are widely held (both by speech therapists as well as by members of the stammering self-help community).

This shift in the approach has not been so beneficial to people whose stammering is severe.

Is it really always OK to take our time?

One such assumption is that it's always OK to take our time. The problem with this assumption is that there are many situations in everyday life where a certain speed is necessary. Occasionally we are faced with emergencies where fast communication is essential in order to save lives; and frequently we are faced with more mundane situations where speed is necessary in order to avoid incurring the wrath of other people.

One such example is when ordering a ticket at a train station, at rush hour, when there is a queue of people behind you waiting for you to finish. For people with severe stammers, such situations can definitely lead to extreme anxiety and stress responses. In such situations I would argue that trying to resist time pressure and “take your time” is not only futile, but also counterproductive, inasmuch as it is likely to provoke palpably negative responses from the people behind you who are worried about missing their train.

So what can one do? Definitely, it is good to try and ask for the ticket. But, if you doubt your ability to get the words out more or less straight away, it will be much less traumatising for you if you have a pre-prepared note ready and waiting that you can show the ticket person should your speech let you down. Indeed, if you have a written back-up ready and waiting, it greatly increases the chances that you will be able to successfully ask for the ticket… because the knowledge that you have a written back up will stop you worrying about not being able to get the message across. 

It will be much less traumatising if you have a pre-prepared note you can show the ticket person should your speech let you down.

Substituting words, or giving up

A second unhelpful assumption is… 'It’s always bad to substitute words or to give up'.

Certainly I believe it's always good to try and say the words we want to say – once, or perhaps twice. But, if a word still won’t come out, to then keep on trying to say it increases the likelihood of eliciting negative listener responses and increases the likelihood that you will be traumatised.

Certainly I believe it's always good to try and say the words we want to say – once, or perhaps twice.

Often when we get stuck on a word, the listener can guess or predict what that word is… in which case why not just skip it and move on? Alternatively, we may be able to insert an equivalent word in its place; or we might be able to make ourselves understood with gestures; or we may be able to write it down. Or we may simply be better off giving up and perhaps trying again at another time, or in another way. 

Any of these alternative options are likely to be less traumatising than continuing to try to say a word that won’t come out. They may sound like forms of avoidance, but they are not – as long as we have indeed tried (once) to say the desired word. (Webmaster’s note: ‘Avoidance’, which is common amongst people who stammer but generally discouraged by therapy and self-help approaches, involves disguising one’s stammer by, for example, switching words or avoiding some speech situations: see the ‘Avoidance’ tag.)

Therapy techniques leading to negative reactions

Similarly (see footnote 2), some traditional speech therapy techniques may elicit negative responses from listeners, especially if those techniques require us to slow down or to repeat words we have already said. One such example is that of “Cancellations”, which are routinely taught in the UK as a part of Block Modification Therapy (Van Riper, 1973).2

Van Riper encouraged students to do cancellations in real-life situations. The idea behind them was to prevent students from further reinforcing their tendency to use force to push through blocks by withholding the reward of successful communication until after they have gone back and said the problem word 'correctly'.

However, to my mind Van Riper's reasoning greatly underestimated the potential for traumatic consequences of trying to employ this technique in real-life situations. In particular, it overlooks the fact that cancellations can be frustrating for the listener (who more often than not will have already understood or guessed the word being repeated) and can result in the speaker experiencing acute feelings of time-pressure.

I agree with Van Riper (see footnote 3) that it is important not to reinforce the habit of pushing through blocks. The use of force to push through blocks definitely does more harm than good. However, to my mind, cancellations are not a sensible alternative. If anything, cancellations probably increase the tendency to block in the future3. Whatever the case, there are better ways of going beyond blocks - that do not reinforce the use of force and that do not require us to keep trying to make movements we cannot make.

Approaches should encourage us to say what we can

On a broader note, I would argue that therapy and self-help approaches are likely to work best when they encourage us to get on with saying what we can say rather than to keep trying to say things that we can’t say. To keep going back wastes time and increases the feeling that one is under time-pressure.  

Consequently, if we can’t say a sound or a word more or less straight away, it is better to give up trying to say that sound or word and move on. In so doing, we increase the chances that the listener will be able to guess any missing words from the overall context. Then, on the odd occasion where it’s really necessary in order to get a message across, we should feel free to substitute a different word or use an alternative mode of communication.

If we can’t say a sound or a word more or less straight away, it is better to give up trying to say that sound or word and move on.

Psycholinguistic studies of typically fluent speech show that speakers frequently miss out sounds and even whole words, and that these omissions do not reduce the comprehensibility of what they say (McClelland & Elman, 1986). Indeed, as often as not, listeners don’t even notice when sounds or words have been missed out. 

Such evidence suggests that, generally speaking, to maximise the chances of successfully getting a message across, and to minimise the likelihood of being traumatised, on balance it is generally more useful to focus on maintaining the forward flow of our speech than on trying to clearly enunciate each and every word.


  1. Here, I am specifically referring to the 70% concordance rates for stuttering in identical twins compared to for non-identical twins. e.g. 72% vs 9% (Bloodstein 2008) ; 52% vs 12% (Ooki, 2005). Back.
  2. Cancellations involve the following… When you start to stutter on a word, continue on to the end of that word. Then pause deliberately and then say it again, gently, in slow motion before continuing on. Back.
  3. I should emphasise that it is just this one particular aspect of Block Modification therapy (known as Cancellations), that I believe does more harm than good.  Other components of block modification therapy can play a valuable role in stammering management. Back.


  • Bijleveld, H.-A. (2015). Post-traumatic Stress Disorder and Stuttering: A Diagnostic Challenge in a Case Study. Procedia-Social and Behavioral Sciences, 193, 37-43.
  • Bloodstein, O. (1975). Stuttering as tension and fragmentation. In J. Eisenson (Ed.), Stuttering: A second symposium (pp. 1-96). New York: Harper & row.
  • Bloodstein, O., & Bernstein Ratner, N. (2008). A handbook on stuttering (6th ed.). NY: Delmar.
  • Brocklehurst, P. H., Lickley, R. J., & Corley, M. (2013). Revisiting Bloodstein's Anticipatory Struggle Hypothesis from a psycholinguistic perspective: A Variable Release Threshold Hypothesis of stuttering. Journal of communication disorders, 46(3), 217-237.
  • Buehner, M. J. (2014). The psychology of time and causality. Euresis Journal, 7, 3.
  • McClelland, J. L., & Elman, J. L. (1986). The TRACE model of speech perception. Cognitive psychology, 18(1), 1-86.
  • Ooki, S. (2005). Genetic and environmental influences on stuttering and tics in Japanese twin children. Twin Research and Human Genetics, 8(01), 69-75.
  • Perkins, W., Kent, R., & Curlee, R. (1991). A theory of neuropsycholinguistic function in stuttering. Journal of Speech and Hearing Research, 34(4), 734.Porges, S. W. (2011). The Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-regulation (Norton Series on Interpersonal Neurobiology): WW Norton & Company.
  • Van Riper, C. (1973). The treatment of stuttering: Prentice-Hall Englewood Cliffs, NJ.
Two women in running outfits holding flags and looking at the camera
Tayo & Bhupinder
A speaker on stage at STAMMAFest 2023

Become a member

It's free

Join the movement to change how people understand and react to stammering.

Sign up

Campaign. Fundraise. Connect. Meet. Vote. Talk.