The claim comes from Cardiff University professor Phil Cooke, who compared the performance of Wales and Scotland.
Scotland's wider and clearer powers had allowed its devolved government to be more confident and successful, he found.
Prof Cooke said: 'Stronger powers tend to help build better policy making. Wales has suffered from timidity caused by institutional uncertainty.'
Prof Cooke said: 'There is evidence weak devolution, of the kind that may be anticipated for the English regions, is a poor option for dynamic, experimental policy-making.'
Wales' weak powers meant it was unable to attract top politicians or civil servants, and 'has been conditioned by a local authority mentality', the report noted.
But Wales' economic development and transport minister Andrew Davies said he was 'mystified' by the claims, as Scotland had not yet used its primary legislation powers in economic development.
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