List of studies on Neuro-linguistic programming

List of studies on Neuro-linguistic programming (NLP) summarizes the many studies that have been performed relevant to NLP, since the early 1980s. These tend to be of three types: studies, metastudies, and research in related fields (notably cognitive science and neuroscience).

A fourth kind of evidence, called anecdotal evidence, refers to end-user reports, and is often of a less controlled nature or less carefully analysed in a rigorous manner. Anecdotal evidence may be considered suggestive, and a direction to further research,but scientists do not consider it "proof" in its own right.

This article is intended to be read in conjunction with NLP and science, which summarizes and discusses the findings overall and considers how and where NLP stands in science.

Overview of key aspects of research into NLP
Actual clinical studies have been more productive, but many are merely suggestive or lack formal academic rigor. Equally (as researchers have pointed out), attempts have also been greatly obfuscated by many other factors, not least of which are unrealistic claims by some practitioners, poor scientific understanding of the subject being researched, failure to fully consider, control and understand all key variables, and often, lack of high quality experimental design. Key issues expected or highlighted include:
 * 1) NLP is intended to be used to a goal, and contains redundancy. That is, since no single strategy or approach is expected to be 100% consistent (since people vary so much), but NLP's approach overall is believed to have a better chance of producing notably more valuable information, and better potential change, in a more systematic manner, and in a wider range of circumstances, than previous alternatives. It is important to measure its in situ effectiveness rather than its assumptions, many of which are metaphorical.
 * 2) People can misunderstand themselves, and therefore their goals are moving goals. NLP allows for this. The measure of "success" is very often subjective to the client, or may change during working, and this is an expected aspect of working with people.
 * 3) NLP relies on micro-observation and virtuosity (i.e., smoothness of a wide range of skill use). It is important that skilled NLP practitioners are involved in planning, and (where appropriate) as elements within experimental design, to take account of this.
 * 4) Not all NLP training is equal. It is important when studying "NLP" to study excellence in the field, rather than niche or exaggerating practitioners.

Generally supportive

 * Milton and Meta Models
 * In a peer-reviewed study, Bulent Turan and Ruth M. Townsley Stemberger found that "matching another person's representational language enhances perceived empathy." The researchers placed a screen between the conversational partners in order to eliminate visual cues to empathy.
 * In another peer-reviewed study, professors Tanya Chartrand and John Bargh report that when experimenters mirrored subjects, the subjects reported that the experimenters were "more likable" and that they had had "smoother interactions" with them. They call this the "chameleon effect."  In addition, they found that people who were rated high on empathy mirrored their conversational partners more frequently.
 * Researchers at Stanford programmed an AI to mimic student movements while explaining a possible new university policy. An article in Wired explains that 7 out of the 69 students detected the mimicry, but the remaining students who did not detect it "liked the mimicking agent more than the recorded agent, rating the former more friendly, interesting, honest and persuasive. They also paid better attention to the parroting presenter, looking away less often. Most significantly, they were more likely to come around to the mimicking agent's way of thinking on the issue of mandatory ID."
 * Sandhu et al. found that NLP mirroring had a significant effect on various measurements of rapport in a cross-cultural counseling scenario.
 * Alan Brandis found that self-anchoring was "strongly related" to changes parental anger responses.
 * Horst Reckert studied one-session anchoring as a way to treat test anxiety with positive results. The author used mental training as a control.
 * Thomas Macroy found that more dissatisfied families substantially correlated with meta-model violations, and concluded that "challenging metamodel patterns is an important way to enhance the ability to achieve satisfaction socially."
 * Cheek demonstrated that NLP Milton Model language use is capable of reaching and influencing the unconscious mind by inducing 3000 patients to respond with formal yes/no hand signals to questions while fully anesthetized.
 * Henry Asbell found that predicate matching was perceived as the "most helpful" of 4 strategies and resulted in higher ratings for counsellor empathy.
 * Yappo (1981) found that when subjects were put in trance using a variety of inductions in different sensory systems, and EMG (electromyograph) and self-assessment were used to measure effects of predicate matching, both measures showed that deeper trance was induced when the preferred sensory system was used
 * Organic conditions
 * Judith Swack, in an uncontrolled, non-peer reviewed study, used the NLP allergy cure on a group of ten people. The initial results were 70% success with 30% of these 7 relapsing over time. Of these 3, 2 fully recovered when other NLP techniques (including timeline therapy and V/K dissociation) were used.
 * Hanne and Jorgen Lund tested NLP on asthmatics, finding that the lung capacity of members of the control group declined on average approximately 50ml, the members of the experimental group improved approximately 200ml. In the experimental group, unstable lung function measurements fell to under 10%, and the use of inhalers and acute medication both fell to zero.
 * Unterberger Ulbrich (1998) found that when NLP was used to treat serious chronic conditions in clinical trials, comprising 12 hours over 3 weeks, they "prove to be quite successful procedures" and "significant results show up", noting that "the participators in the training judge the success of their rehabilitation measures throughout more positively than the members of the control's group".
 * Clinical psychology
 * Konefal (1992) found that, "Results confirm the effectiveness of neurolinguistic programming in lowering trait anxiety and increasing the sense of internal control"
 * Genser-Medlitsch & Schütz (1997) tested the effects of NLP master practitioners working on 55 clients with severe DSM conditions, many of whom were on psychiatric drugs. The control group of 60 had milder symptoms. After treatment of the NLP group, 2% felt no different, 98% felt better or much better, none felt worse (control group: 48% no different, 36% better, 15% worse). After therapy, the clients who received NLP scored higher in their perception of themselves as in control of their lives (with a difference at 10% significance level), reduced their use of drugs, used more successful coping methods, and reduced symptoms such as anxiety, aggression, paranoid thinking, social insecurity, compulsive behaviours, and depression. Positive changes in 25 of 33 symptom areas (76%) occurred as a result of NLP, positive changes in 3 areas occurred in both NLP and control groups. The researchers concluded "It could be established that, in principle, NLP is effective in accordance with the therapeutic objective."
 * General Psychology
 * Miranda Paula & Palma examined in clinical trials whether NLP could help children and parents in shanty towns. They used an NLP intervention program over 15 sessions (approx 10 helped with NLP, 27 control), measuring children’s psychomotor development, home environment and maternal mental health before and after. They concluded "There was a trend that indicated positive effects on the home environment".
 * Gerald Davis found that NLP's "structure, terminology, and sound theoretical principles resulted in gathering valuable process information" when counselling prelingually deaf adults
 * Frank (1997, Germany) investigated NLP in social work, finding "enormous changes" and that "very many of the people indicated that they could increase their adaptability, feel technically more competent and make a more intensive self reflection", summarizing that it had "fallen out very positively"
 * Loiselle (1985, University of Moncton, New Brunswick) tested various spelling strategies and found: control=no change, "visualize"=10% better, "visualize up/right" (ie NLP Visual) = 20-25% better, "visualize down/left" (ie NLP Kinesthetic)=15% worse.
 * Almost identical results were obtained by Malloy (1989) - the NLP spelling strategy produced a 25% improvement in spelling ability (and 100% retention) compared to no change in a control group but that spellers told to visualize in what NLP claims is a Kinesthetic manner (down/left) were scored around 10% worse.
 * Wilhelm (1991, Germany) tested the "swish" pattern for nail-biting, finding "significant variations of the nailbiting" and that results were stable up until followup
 * V/K dissociation
 * Einspruch (1988) found "marked improvement" over an 8 week period in a test of 31 patients who undertook NLP phobia treatment
 * Koziey and McLeod (1987) found that the NLP V/K technique produced a "positive reduction in anxiety in teenage rape [trauma]"
 * Muss (1991) examined the impact of NLP V/K technique on 19 insurer-referred police officers who met DSM-III post-traumatic stress disorder criteria, following up at 3-24 months. Most stated it had greatly helped, in long term followup 100% of those reached confirmed freedom from recurrence.
 * Dietrich (2000) reviewed NLP V/K dissociation trials, and concluded that NLP was "promising" and that "intrusive symptoms, avoidance behaviors, and interpersonal and occupational functioning improved for many of the participants in the studies reviewed"

Mixed or indeterminate findings

 * Predicate matching Heap (1988) found that findings were "on the whole" negative, but also that "a number of positive outcomes" were reported. He interprets this to mean that there was an effect but it was perhaps more general than expected, noting that this would agree with expectations of NLP writers and also other findings that "with increasing familiarity, client and counsellor tend to converge in their usage of certain linguistic structure".


 * Weight loss Bott (1995) found that NLP gave "partially positive effects" for treating psychogenic weight loss. Unclear if there was a control group.


 * Management learning Dowlen (1996) performed own research and also reviewed the existing research, to examine whether NLP was "help or hype" in management training. He concluded that:
 * "NLP techniques using language patterns and questioning techniques appear to be of use... existing research evidence is limited and inconclusive... NLP is enthusiastically supported by those who practise it, and that is both its strength and potential weakness."


 * NLP-trained observers and eye movement existence and detection Buckner (1987) found that "coefficients of agreement (Cohen's K) between participants' self-reports and trained observers' records indicate support for the visual (K=.81, p<.001) and auditory (K=.65, p<.001) portions of the model", and that "interrater agreement (K=.82) supports the NLP claim that specific eye movement patterns exist and that trained observers can reliably identify them"


 * Predicate matching and eye movements Baddeley (1991) found positive correlation between predicates and certain predicted eye movements

Meta-studies and similar commentaries on research

 * Sharpley (1984) performed a metastudy of 15 studies seeking to test for a 'preferred representation system.' He concluded strongly that there was "little supportive evidence and a large amount of data opposing the validity of the concept." The concept of a PRS was (whether earlier or later than this) dropped within NLP.


 * Einspruch & Forman (1985), responding to Sharpley, criticized all 39 studies to that date (including all 15 of Sharpleys') for serious errors, and concluded that as a result it was "not possible at this time to determine the validity of either NLP concepts or whether NLP-based therapeutic procedures are effective":
 * "There is a growing body of empirical literature on Neuro-linguistic programming (NLP). A review of this literature by Sharpley (1984) failed to consider a number of methodological errors. In the present article the authors identify six categories of design and methodological errors contained in [empirical studies] through April 1984. These categories include (a) lack of understanding of the concepts of pattern recognition and inadequate control of context; (b) unfamiliarity with NLP as an approach to therapy; (c) lack of familiarity with the NLP "Meta-Model" of linguistic communication; (d) failure to consider the role of stimulus-response associations; (e) inadequate interviewer training and definitions of rapport; and, (f) logical mistakes. ... Suggestions are offered for improving the quality of research on NLP."
 * Some of these criticisms were later challenged or rebutted by Sharpley, but the majority of them are, in general, accepted.


 * Sharpley published a follow-up review (1987):
 * "There are conclusive data from the research on NLP, and the conclusion is that the principles and procedures suggested by NLP have failed to be supported by those data. Perhaps NLP principles are not amenable to research evaluation. This does not necessarily reduce NLP to worthlessness for counseling practice. Rather, it puts NLP in the same category as psychoanalysis, that is, with principles not easily demonstrated in laboratory settings but, nevertheless, strongly supported by clinicians in the field."


 * Sharpley 1987 quote: “There are conclusive data from the research on NLP, and the conclusion is that the principles and procedures of NLP have failed to be supported by those data” Then he (Sharpley) says “On the other hand, Einspruch and Forman (1985) implied that NLP is far more complex than presumed by researchers, and thus, the data are not true evaluations of NLP. Perhaps this is so, and perhaps NLP procedures are not amenable to research evaluation. This does not necessarily reduce NLP to worthlessness for counseling practice. Rather it puts it in the same category as psychoanalysis, that is, with principles not easily demonstrated in laboratory settings but, nevertheless, strongly supported by clinicians in the field. Not every therapy has to undergo the rigorous testing that is characteristic of the more behavioural approaches to counseling to be of use to the therapeutic community, but failure to produce data that support a particular theory from controlled studies does relegate that theory to questionable status in terms of professional accountability” Right at the end of the article the sentences read: “Elich et al referred to NLP as a psychological fad, and they may well have been correct. Certainly research data do not support the rather extreme claims that proponents of NLP have made as to the validity of its principles or the novelty of its procedures.”


 * Heap says of his own research into matching predicates (1988) that:
 * "Einsprech and Forman are probably correct in insisting that the effectiveness of NLP therapy undertaken in authentic clinical contexts of trained practitioners has not yet been properly investigated."


 * Druckman (1988) reports that anecdotal evidence on NLP is broadly credible and positive, but that most attempted studies are heavily flawed, such as (a) equating subjective empathy with clinical effectiveness, (b) studying NLP as a theory, rather than as an influencing technique pitted against existing influencing techniques, (c) Attempting to replicate findings of NLP using subjects, observers, or experimental designers who lack NLP training, and (d) lack of studies on NLP as a trainer modeling system. He concludes that as a result of the study flaws, and despite the anecdotal support:
 * "Ignoring where the burden of proof lies, the fact remains that the experimental evidence fails to provide support for NLP... Overall, there is little or no empirical evidence to date to support either NLP assumptions or NLP effectiveness."


 * Platt (2001) observed that whilst studies evaluating specific NLP points such as predicates, representation systems and eye movements tended to give positive results only around 15-35% of the time, when he examined studies of the effects of NLP applied in its complete context, in this case phobia cures, "56% found positive evidence to support NLP's effectiveness."


 * Thompson et al (2002) question the current research and subsequently propose further longitudinal studies, "The research question is how to measure the impact of NLP training on individual and organisational performance. The existing literature provided little evidence of the efficacy of NLP and provided no templates for analysis. There were no examples of longitudinal studies. A review of four online databases (PsycInfo, Eurobusiness ASAP, Proquest, and First Search) gives 54 citations of which only eight are research studies. Four indicate positive benefits, and four indicate no measurable effect. Einspruch and Forman (1985) give six categories of error in the research on NLP, the major of which is inadequate control of context. In a discussion of these findings, Sharpley (1987) details seven studies (not included in the above total) that demonstrate that the research data does not support the basic tenets of NLP. It is noteworthy that this literature is based in the positivist psychological tradition and many of the examples are in therapeutic areas, e.g. phobia cure and counselling. Interest in this area appears to fade in the early 1990s and there are few reported studies after this date. Dissertation Abstracts International reveals five studies, four of which have a conventional research base. Two of the studies (teaching, and post-traumatic stress) revealed no significant effects. Two, on eye movements and leadership revealed positive effects. Young’s (1995) thesis shows that the leaders made lasting progress on achieving desired outcomes and reported growth, and the students attributed change to the various NLP course components. Young’s (1995) The study included interviews one year after the NLP intervention.. The review of literature does not provide a firm base for a belief that NLP has a lasting effect. Many of the studies are arguably methodologically flawed . Their “flaws” raise considerable methodological and method issues. This view is supported by the positivist stance of Baddeley (1989) that a final verdict (on NLP) is withheld until further clinical studies and experimental investigations are reported... "

Findings within neuroscience and cognitive science

 * NLP and neurotransmitter/neurological activity Baxter (1994) found that NLP reframing used to treat obsessive compulsive disorder in place of Prozac resulted in the same raised serotonin levels and reduced caudate nucleus activity as control subjects who took medication (as measured by Positron Emission Tomography scans of the brain)


 * Submodalities and sensory perception Visual submodalities have been shown to affect kinesthetic states, for example room color has an effect on temperature perception (Berry, Journal of Applied Psychology 45/4) and packaging color changes the effectiveness of the placebo effect (Buckalew and Ross, 1981)