| ISLE | Chapter 9
| Attentional Blink and Repetition Blindness: Experiment
If we are following letters and responding to S, there might be a lag of 4 letters between one S and the next, or there might be a lag of 10 letters between one S and the next target (typically another letter). One question we can ask is whether having just seen a target affects the ability to detect the next target. It turns that out it does, if the second stimulus occurs within 500 ms (half a second) of the first stimulus. This phenomenon is called attentional blink, which refers to the tendency to miss the second appearance of a target in an RSVP task if it is too close.
In this experiment, you can mainipulate some of the parameters of the RSVP task and see how it impacts attentional blink.
To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.
On this tab you can adjust the type of stimulus and the various parameters of the motion of the stimulus to see how this might effect the aftereffect. The settings include the following:
Presentation Rate (ms): the at which the letters are presented in the RSVP.
Non-target color: set the non-targets to be either black or selected at random from
a small set of colors. Red is one of the random colors.
Color of First Target is: choose if the first target is black or colored like the rest of the
letters (Same) or Red.
Color of Second Target is: the same as the first target or the same as the
rest of the letters in the list (black or colored).
Item Size: choose the font size of the letters.
Background Level (display values): the brightness of the background, in basic display units.
This variable alters the contrast between the letters and the background.
Duration of Fixation (ms): how long the fixation mark is on (ms).
Reset At the top of the settings page is a Reset button. Pressing this button restores the method settings to their default values.
On this tab you can adjust how the method will work. The settings include the following:
Number of Trials/Separation: how many trials at each level of separation between
the two targets.
Percentage of Trials with Second Target: the percentage
of trials where the second target is presented (there is always a first target).
Number of Levels of Separation (must be less than half total
number of items in list): this is the principle independent variable during the
experiment. How many separation levels, starting with 1 (or the two targets are
adjacent in the list) and counting up.
Reset At the top of the settings page is a Reset button. Pressing this button restores the stimulus settings to their default values.
On the Experiment tab, press the space bar or the Start button on the screen to start the experiment. Keep your eyes fixated on the red plus sign in the middle of the screen. After the fixation interval, the plus sign will be replaced by a string of letters, one or both of the targets will be presented. The targets are S and T. When the string of targets has been presented, you will be asked which targets you saw. Press the key or the button to indicate which targets you saw. Be as accurate as you can about what you saw, not what you think you saw.
You data will be presented on this tab. On the x-axis will be the separation of the two targets. On the y-axis will be the percentage of times you reported seeing the target. To display the data as values Show Data button.
To see the percentage of trials where you correctly identified the target in the one target trials, press the One Target Pct Detect button.
Change the settings below to alter the stimulus parameters in this experiment.