Heinz appointed Conquest following a four-way pitch including Millward Brown, Hall and Partners and Research International.
Conquest will conduct brand and advertising research across all of Heinz's packaged food brands.
The agency will use its Metaphorix software, which measures consumers' unconscious emotional reactions to brands through interactive online animations.
Conquest will also use its Metaphorix software to conduct the brand and advertising research for Scottish Power.
David Penn, co-founder of Conquest, said: "Metaphorix is the culmination of years of work applying breakthroughs in cognitive linguistics to the problems of consumer behaviour.
"Until now research has worked on the assumption that brand decisions are conscious, explicable and rational.
"Clients now understand that in reality our behaviours and responses to brands are highly emotional. As consumers we say one thing and do another."