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The lab report should be about the Coglabs that were completed for class. You should be explaining what happened in each of the Coglabs and explaining their subsequent results. For this paper, the only time it would make sense to use sources other than Coglab is in the intro and discussion sections to support your explanation of a concept. The methods and results section should speak strictly to what you did in the Coglab. Stuff regarding the topic, Categorical Perception: Discrimination
Background
People perceive most stimuli continuously. For example, when you look at a rainbow, you see a smooth transition from red to yellow (like the image below):
Continuous Perception
You usually do not perceive stimuli categorically. Categorical perception means that you see either pure red or pure yellow and nothing in between (like the image below):
Categrical Perception
This is called “categorical” perception because, instead of getting a percept that is ambiguous, you get a percept that perfectly matches an ideal example of a particular category. One thing that people seem to perceive categorically is speech (Harnard, 1987). What is interesting about this is that even when the physical stimuli change continuously (like the upper image), people perceive it categorically (like the lower image).
For example, both /b/ and /p/ are stop consonants: To produce these, you close your lips, then open them, release some air, and the vocal chords begin vibrating. Hold your hand in front of your mouth and say /ba/ and then /pa/. The difference between /ba/ and /pa/ is the time between the release of the air and the beginning of the vibration. This is referred to as voice onset time or VOT. For /b/, VOT is very short. Voicing begins at almost the same time as the air is released. For /p/, the voicing is delayed.
Researchers can construct a series of stimuli in which the VOT changes in small steps. When people are asked to identify these stimuli, they generally have no difficulty: The first few are identified as /b/ and the second few are identified as /p/. What is most interesting is how the middle items are identified. Unlike most other stimuli, people do not report hearing something that is a bit like /b/ and a bit like /p/. Rather, they report hearing either /b/ or /p/.
To demonstrate categorical perception of speech stimuli, you really need two different measures. This lab provides one of those measures: it examines your ability to tell whether two sounds are the same or different. The second (which is provided in the Categorical Perception: Identification experiment) lets you find the point at which your percept changes from /ba/ to /pa/ through an identification task.
The stimuli used in this lab are artificial: they were generated by a speech synthesizer. The reason is to ensure that the only difference between the stimuli is the VOT.
Instructions
If you have logged in, you’ll see a rectangle below. Make sure that you can see the full area before you begin the lab.
On each trial, you will hear two sounds. Your task is to report whether they are the same or different.
Occasionally, the sounds that are played may be distorted. If you did not hear the sound clearly, you can re-play the sounds.
There are a total of 70 trials.
At the end of the experiment, you will be asked if you want to save your data to a set of global data. After you answer the question, a new Web page window will appear that includes a debriefing, your data, your group’s data, and the global data.
Tablet Specific Details
If you are using a tablet, tap the Start Next Trial button to begin. Tap either the Same or Different button to indicate whether the two sounds were the same or different. Tap Replay to hear the sounds again.
Computer Specific Details
If you are using a computer, click the Start Next Trial button to begin. Click either the Same or Different button to indicate whether the two sounds were the same or different. Click Replay to hear the sounds again. More stuff about the topic, Categorical Perception: Identification
Estimated time to complete lab: 35 minutes
Background
People perceive most stimuli continuously. For example, when you look at a rainbow, you see a smooth transition from red to yellow (like the image below):
Continuous Perception
You usually do not perceive stimuli categorically. Categorical perception means that you see either pure red or pure yellow and nothing in between (like the image below):
Categrical Perception
This is called “categorical” perception because, instead of getting a percept that is ambiguous, you get a percept that perfectly matches an ideal example of a particular category. One thing that people seem to perceive categorically is speech (Harnard, 1987). What is interesting about this is that even when the physical stimuli change continuously (like the upper image), people perceive it categorically (like the lower image).
For example, both /b/ and /p/ are stop consonants: To produce these, you close your lips, then open them, release some air, and the vocal chords begin vibrating. Hold your hand in front of your mouth and say /ba/ and then /pa/. The difference between /ba/ and /pa/ is the time between the release of the air and the beginning of the vibration. This is referred to as voice onset time or VOT. For /b/, VOT is very short. Voicing begins at almost the same time as the air is released. For /p/, the voicing is delayed.
Researchers can construct a series of stimuli in which the VOT changes in small steps. When people are asked to identify these stimuli, they generally have no difficulty: The first few are identified as /b/ and the second few are identified as /p/. What is most interesting is how the middle items are identified. Unlike most other stimuli, people do not report hearing something that is a bit like /b/ and a bit like /p/. Rather, they report hearing either /b/ or /p/.
To demonstrate categorical perception of speech stimuli, you really need two different measures. This lab provides one of those measures: It lets you find the point at which your percept changes from /ba/ to /pa/ through an identification task. The second (which is provided in the Categorical Perception: Discrimination experiment) examines your ability to tell whether two tokens are the same or different.
The stimuli used in this lab are artificial: they were generated by a speech synthesizer. The reason is to ensure that the only difference between the stimuli is the VOT.
Instructions
If you have logged in, you’ll see a rectangle below. Make sure that you can see the full area before you begin the lab.
On each trial, you will hear one sound. Your task is to report what it most sounds like, either /BA/ or /PA/.
Occasionally, the sound that is played may be distorted. If you did not hear the sound clearly, you can re-play the sound.
There are 10 trials for each stimulus, for a total of 90 trials.
At the end of the experiment, you will be asked if you want to save your data to a set of global data. After you answer the question, a new Web page window will appear that includes a debriefing, your data, your group’s data, and the global data.
Tablet Specific Details
If you are using a tablet, tap the Start Next Trial button to begin. Tap either the ba or pa button to indicate what the stimulus most sounds like. Tap Replay to hear the sound again.
Computer Specific Details
If you are using a computer, click the Start Next Trial button to begin. Click either the ba or pa button to indicate what the stimulus most sounds like. Click Replay to hear the sound again.