Having tried the apple juice, chocolate and biscuits, the volunteers gave samples described as ethically produced - either organic or Fairtrade - much higher scores for taste.
Organic food is produced by natural methods, employing high animal welfare standards and without using harmful chemicals, while the Fairtrade Foundation ensures farmers and producers in developing countries get a fair price for their goods and are encouraged to protect the environment.
There is evidence that eating organic foods has health benefits such as higher vitamin and antioxidant levels in certain crops, but no research has shown that its flavour is actually better.
Despite this, consumers who pride themselves on backing this type of food production often claim the flavour is far better.
The findings, by academics at Abertay University in Dundee, follow previous studies that showed how the mind can play tricks on the senses and judgement.
The research suggests that once a consumer has tried ethical food, the apparently superior taste experience will act as a reward mechanism to make them continue buying that product, despite its typically higher price.
Dr Boyka Bratanova, who led the study, found the "moral satisfaction" that comes from eating ethically produced food has a measurable impact on the enjoyment of that food's taste.
She added: "What is absolutely central is the consumer must believe that ethical food production is important.
"If they don't value the reasons behind Fairtrade or organic food production then they will not experience the moral satisfaction effect.
"However, if you are interested in animals being raised humanely or farms being run on organic principles, then it seems you are able to gain even more enjoyment from eating that ethical food.
"There has been a huge, sustained increase in demand for ethical food around the world, and in the UK in particular.
"If this was just a fad or a fashion you'd expect any increase to be temporary as the fashion passed or the market became saturated.
"However, quite the opposite has happened. It seems that the demand for ethical food is continuing to grow."
The findings draw together a large-scale survey across eight European Union nations, including the UK, and experimental studies at Belgian and British universities to measure the effect of moral satisfaction on expectations of taste and actual taste.
It follows a study this year at the University of Bonn in Germany which found that people who tried a $10 bottle of wine and rated it for taste gave it a higher score if they were given it again but told it was a more expensive wine.
Bernd Weber, co-author of that research, said: "People enjoy identical products such as wine more if they have a higher price tag."
- Daily Mail
