Does attention have a causal impact on risky decisions? We address this question in a preregistered experiment in which participants accept or reject a series of mixed gambles while exogenously varying how information can be sampled. Specifically, in each trial participants observe the outcomes of a mixed-gamble with gains and losses presented sequentially. To isolate the causal role of attention on the decision process, we manipulate for how long a specific attribute is presented before showing the next one (e.g., 600 ms/800 ms vs 400 ms). Our results partially confirm our preregistered hypotheses that longer exposure to an attribute increases its weight on the decision. While we find no effects on choice frequency, we observe specific effects on the decision weights of our Random Utility Model. Presenting losses longer (for 600 ms, but not 800 ms) than gains (400 ms) leads to increased sensitivity for losses. When gains are presented for longer (600 ms and 800 ms) than losses (400 ms), the participants show increased sensitivity to both gain and loss values in their decision. Loss aversion reflects this trend across attention treatments, but differences remain non-significant. Further exploratory analyses show that specifically participants with higher impulsiveness become more sensitive to attribute values when gains are presented for longer. Jointly, these results support the notion that attention has a causal impact on the sensitivity to specific attributes during risky choice. Moreover, our results underline the moderating role of impulsiveness on the relationship between attention and choice.