The benefits of collaborative activities have been demonstrated in many domains, but there remain mixed results across several others as to whether collaborative groups can achieve greater performance than individuals, and can achieve greater performance than nominal group comparisons. Here we develop a task that is especially suited to testing collaborative gains. In a collaborative crossword game, two individuals solved puzzle questions either alone or collaboratively through discussion. When talking, participants solved more puzzle questions, solved them more quickly and accurately, and in general seemed to recall the words from collaborative contexts better than from matched independent contexts. By extracting the audio of their interaction, we also demonstrate interesting relationships between spoken interaction and performance on the collaborative tasks. This task environment further substantiates the notion that, in the context of knowledge retrieval, two heads are better than one.