There have been a number of literature reviews published in peer review journals on the subject of dolphin therapy, each of which identified significant flaws in the existing research studies.
Humphries reviewed a number of studies which purported to have found positive benefits to people from DAT and found that all the research examined "failed to adequately control for a number of possible threats to validity or alternative explanations".
She notes: "The studies included in this synthesis are so plagued with methodological flaws that claims that the reported outcomes are due to dolphin assisted therapy may be erroneous" and that "the results of the synthesis do not support the notion that using interactions with dolphins is any more effective than other reinforcers for improving child-learning or social-emotional development".
She also states: "Claims of the effectiveness of using dolphins as a procedure for improving the behaviours of young children with disabilities are therefore not supported by available research evidence".
Marino and Lilienfeld conducted a review of studies published between 1999 and 2005, and found that "all five studies were methodologically flawed and plagued by several threats to both internal and construct validity".
They found that a consistent problem throughout the studies reviewed was a failure to control for other factors of the treatment which might influence results (for example: being in the water; swimming outdoors; interacting with therapists; experimental expectancy effects).
They concluded that: "the abundance of serious threats to validity in the five studies we examined renders each of their conclusions questionable at best, and entirely unwarranted at worst".
Fiksdal et al conducted a review of studies five years after Marino and Lilienfeld. They concluded
“The majority of the studies conducted supporting the effectiveness of dolphin-assisted therapy have been found to have major methodological concerns making it impossible to draw valid conclusions.”
Please note: The research reviews listed above did not take account of some of the later studies and their conclusions should therefore be treated with some caution. However we believe that the overall thrust of their conclusions is still valid as the quality of most of the later studies is still quite poor. For example,
For a comprehensive list of potential flaws in research studies, please see ‘Why some autism research studies are flawed’