Ed Yong has an excellent post on how language affects thought :New Nicaraguan sign language shows how language affects thought. Excerpts:
"This is a subtly different idea than the one espoused by the Sapir-Whorf hypothesis, which suggests that different languages influence how speakers think about their world. By contrast, Pyers’ results focus “on those aspects of human cognition that are dependent on acquiring a language, any language”. She says that the room tasks tap into a set of mental skills that “crucially depends on language and that this relationship between language and spatial cognition should hold true for speakers of all languages”.
The Nicaraguan signers may well reveal more ways in which language fundamentally affects thought, for other aspects of the language besides spatial locations became more complex over time. These include ways of signifying mental states, and Pyers has already shown that as these became more sophisticated, so did the signers’ abilities to understand the fact that other people can hold false beliefs. Meanwhile, Ann Senghas and Molly Flaherty, who worked on the current study, are looking at how the emergence of a counting system in NSL affected the numerical skills of the signers.
The grand idea behind all of these singular observations is that as human language evolved, our mental abilities became increasingly entwined with linguistic devices. Those devices are part and parcel of modern language, and thus modern thought. NSL, being a new language, is the exception that proves the rule – as it developed, so did the abilities of those who learned it, from their skills at visualising objects in space to their capacity for understanding the minds of their peers."
P.S. A long discussion in Language Log Hay foot straw foot.