Welcome to the Categorical Perception Experiment website for LING 275! This website allows you to participate in a categorical perception experiment and to view and save your results. You will need these to complete the fourth LING 275 homework assignment.
There are some useful links on the left side; these links will also be available to you at the end of the experiment. Participating in this experiment takes about 10 minutes.
The stimuli used in this experiment come from Stephens & Holt.
The diagram below shows typical results when the experiment is performed with a group of participants. The results shown here are based on the pooled responses from 8 participants.
Please view the graph in color. The y axis shows the proportion of ‘di’ or ‘gi’ responses. The x axis shows the 20 sounds on the continuum.* The yellow/orange line shows the proportion of ‘di’ choices. The blue line shows the proportion of ‘gi’ choices. (Note that there are a total of 20 sounds on the continuum, and each one was presented twice.)
This experiment is meant as a demonstration. In a real experiment, each participant is presented with many more repetitions of each sound to minimize errors (e.g. temporary distraction, simply pressing the wrong button).
*Some of the labels for the 20 sounds are not visible on the x-axis due to formatting limitations.
In these kinds of studies, the second formant (F2) is crucial. As we saw in class, changing the locus (plural: loci) of the second formant is crucial and influences our perception of the place of articulation of the sound (e.g. b/d/g). The diagram below shows a continuum of F2 loci. As we saw in class, different loci (when tail points low/mid/high) play a key role in determining whether we hear [b], [d] or [g]. Experiments usually present participants with a continuum of loci to see whether place of articulation is perceived categorically.
Here you can find a PDF with additional information about categorical perception from the class notes. These materials can also be downloaded from the course Blackboard page.