Thirteen French Psychology researchers were recorded speaking in English. From the recordings, words and sentences were divided into two categories: either pronounced with a strong accent or not. Three Southern British English speakers also recorded the same words and sentences. We then asked French and English speakers to listen to samples pronounced with the three different accents and complete three tasks, which involved recognising words and understanding continuous speech. The results showed that a strong accent made it more difficult for the English listeners to recognise and understand, whereas the French listeners' answers did not differ significantly. The listeners were also asked to give ratings about whether it was difficult to understand and how certain they were of their answers. Ratings showed similar patterns to the listening tasks, but also indicated that a strong accent might require more listening effort.