Specs for Dimberg1

Basic Idea.

• Present sounds and get button-push responses to the sounds.

• Present pictures (negative and neutral), either by themselves or shortly after the sounds.

• Record EMG of corrugator, using BioPac Hardware, maintaining a record of the temporal relationship between the physiological responses and the sounds/pictures.

Overall Sequence of Experiment.

0. Preliminary Instructions

1. Two practice blocks of sound-button task (50 trials per block).

2. Instruction 1

3. Present 5 pictures and record physiological responses to each.

4. Instruction 2

5. One more block of 50 sound-button tasks, with pictures presented on some trials.

0. Preliminary Instructions

Welcome to the experiment Dimberg1. This will be a quick experiment and we think you will find it somewhat interesting. Your task will be very easy. First of all, we will ask you to press one of three keys with your right hand whenever you hear a sound from the computer. The sound will be a voice saying “low”, “middle”, or “high”, spoken in a low-pitched, medium-pitched, or high-pitched sound, respectively. The three response keys are labeled appropriately and are arranged with the high-pitched sound key on top and the low-pitched sound key on the bottom. Thus, you will find the task very natural. Try to respond as quickly and accurately as you can. We will begin with two two-minute sets of trials so you can get used to this task. There is one other thing we’d like you to do. A plus sign will appear shortly before the sounds. Please look directly at the plus sign until it disappears (which will happen when you respond to the sound).

1. Sound Task.

Use wave files from Kalsbeek? Experiment. These sounds are clips of a voice saying “low”, “middle”, or “high” in a low, middle, or high-pitched voice, respectively. The correct response should be M for low, K for middle, and O for high (so the high-pitched key is above the medium-pitched key etc.)

Select sounds randomly and independently on each trial. On each trial, present a plus sign for 500 msec marking the trial, with a 500 msec offset followed by the sound. Collect RT and accuracy and save that for each trial along with stimulus presented and response. There is a 750 msec delay between the offset of one trial and the onset of the cross for the next trial.

2. Instruction 1

In the next block of trials, your task is even simpler: all you have to do is to look straight at the computer screen every time a red plus sign appears in the middle of the screen (which will happen just five times). A picture will appear in the center of the screen. Please just stare straight ahead. Once the picture disappears, you can move your eyes around until the next plus sign appears.

3. Picture Presentations

On each presentation, put up a red plus sign for 1500 msec and then replace it with a jpeg image centered around where the plus sign was. The image should remain up for 2 seconds. You will get a file called pix1.txt containing the names of the 5 jpeg files to be presented. Randomize the order in which the pictures are presented. For testing, just use any convenient jpegs. Collection of EMG and skin conductance should begin 500 msec before the plus sign and continue 1 seconds after the offset of the picture. There is a 2 second delay between the offset of one trial and the onset of the cross for the next trial.

4. Instruction 2

In the next block of trials, you will hear sounds and (occasionally) you will see a picture. When the red plus sign comes up, you should look straight at it. On many trials, a picture will replace the plus sign. All you have to do is: (1) make the button-push response to the sound, and keep your eye on the screen until either the plus sign or the picture disappears.

5. Sound-Picture Block

Present sounds and collect responses as in (1). There should be 60 trials in the block. Present the plus sign for 1000 msec before the sound appears. Take it down at the first moment (a) the picture appears or (b) the subject has responded to the sound. The picture stays up for 1500 msec. There is a 750 msec delay between the offset of one trial and the onset of the cross for the next trial.

We will have a file called pix1.txt containing the names of 20 jpeg files to be presented. The stimulus onset asynchrony between the sounds and the pictures should be 100 msec for 5 of the pictures, 200 msec for 5 of the pictures, 500 msec for 5 of the pictures, and 1200 msec for 5 of the pictures. Randomly pick which 20 trials

*Pix1.txt will contain 25 image file names. The first 5 listed will be used in part 3 of the experiment and the remaining 20 will be used in part 5 of the experiment.