In everyday life, we make hundreds of fast decisions, which we don’t think much about. Some of our decisions are bottom-up i.e. based on the features of a person or an object; others are top-down, i.e. based on the context. Words can be used in a top-down fashion, influencing a context for our decisions. While the effect of words on perception and decision making has been previously well documented, the mechanisms of this top-down influence are still not clear. For example, it has been shown that participants can adopt different strategies when integrating linguistic and visual information. While there is some evidence that participants’ perceptual sensitivity is at play, it has been suggested that an alternative mechanism of decision threshold adjustment can be involved too. This thesis investigates how our decision making is affected by words: what are the mechanisms of language bias on decision making? What are neural underpinnings of language bias? The questions are addressed using a combination of behavioral, computational, neuroimaging and neuropsychological methods.