Demonstrations
We identify hands-on demonstrations of various cognitive phenomena that are central to the study of cognitive science and that are available on the internet or this website. Students can test themselves and experience the phenomena first hand and, in many cases, analyze their own responses quantitatively.Click on any heading below to expand that section. You may then click any white link to view individual demos.
STROOP TASK: The Stroop interference effect demonstrates that even when we want to ignore a written word, it is difficult not to read it. In the Stroop task, you are instructed to ignore a word and name its ink color a fast as possible. The words are color names and when the word is the same as the ink color (e.g., BLUE), response time is faster than when the word is different from the ink color (e.g., BLUE). The difference between the same and different conditions is the Stroop interference effect. It indicates how difficult it is to stop a highly practiced automatic process such as reading. The interference effect has been used as an index of the efficiency of controlled cognitive processes that focus attention on the color, not the word.
In this demo, you press a key to indicate a color and you should practice first to learn the position of the key for each color. Calculate your mean response time in each condition. Did you find Stroop interference? This effect demonstrates the difficulty of stopping a highly practiced bahvaior, i.e., reading
Stroop
Demonstration
The EMOTION STROOP TASK uses basewords that have an inherently emotional meaning, or that evoke emotion for some people. For example, a high arousal, negative word such as MURDER would slow color naming compared to a neutral word for most people, whereas a word like SPIDER would slow color naming for people who fear spiders.
Emotion Stroop
Task Demonstration
BLINDSIGHT: Attention does not always create awareness. In cases of blindsight, patients have a large visual scotoma and no awareness of images that fall in that area. Nevertheless, they can report with above chance accuracy some aspects of objects in the area, all the while objecting that they cannot see anything. Attention to the area within the scotoma improves performance but does not confer awareness on objects in the scotoma (see Banks essay).
Blindsight
Demonstration
The ATTENTIONAL BLINK is a paradoxical effect in which attention makes images harder to see. It occurs when a series of images or pictures is shown very rapidly, at rates up to ten per second. If the participant is asked to report an item cued by an earlier item in the series, the cued item is less likely to be seen than if it is not cued (see Banks essay).
Attentional Blink
Demonstration
CHANGE BLINDNESS demonstrates that while we feel we are "seeing" an entire scene as we look over it, that sense of seeing greatly exaggerates what we actually perceive. In one demonstration two seemingly identical scenes alternate with a 1-second gray field in between. The two scenes are not identical but differ on some obvious feature, such as a bicycle that is in one but not the other. Most people have to watch a lot of switches between the two images before they see the difference, and once they see it they are shocked by how large and easily visible the difference is (see Banks essay).
Change Blindness
Demonstration
Change Blindness
Demonstration #2
VISUAL BOTTLENECK
Visual Bottleneck
Demonstration
Visual Bottleneck
Explanation
INATTENTIONAL BLINDNESS: The ability of unexpected events to capture attention is an important component of functioning in everyday life, with considerable significance for theories of attention (Most, Scholl, Clifford & Simons, 2005). What happens, for example, as you walk through the woods, eyes searching the ground for mushrooms. Do you notice a large rattlesnake stretched out in a sunny spot directly in your path? Does this unexpected stimulus capture your attention allowing an abrupt halt and circumnavigation? Or are you blind to the snake even though it is in your line of vision.
Here is YouTube's version:
YouTube Attentional Blindness
Demonstration
SIZE CONSTANCY - what you see is not always what you percieve.
RELATIVE CONTRAST ILLUSIONS
BISTABLE IMAGES: AMBIGUOUS FIGURES
FIGURE GROUND ILLUSIONS
DEPTH AMBIGUITY
DISTORTION ILLUSIONS
MENTAL ROTATION: Is all thinking verbal? Can we only think in words, not images? Are there analogue modes of thought or is all thought represented propositionally? This demonstration has been used as evidence for the importance of mental images in thinking. There is one trial for practice and then do the 30 experimental trials. Your data including accuracy, angle of rotation, and response time is on the computer clipboard which you can access in Word or Notepad.
McGURK EFFECT: The McGurk Effect occurs when visual and auditory information about a speech sound are in conflict: The mouth movements of the speaker are producing one syllable (e.g., ‘GA’) while the acoustic signal is producing a different syllable (e.g., ‘BA’) and most listeners perceive a different syllable (e.g., “DA”). Test your perception by listening with your eyes closed. This demonstration nicely illustrates the bimodal nature of speech. The "McGurk effect" was introduced McGurk and MacDonald (1976). "Hearing lips and seeing voices", Nature, 264,
746-748.
CATEGORICAL PERCEPTION
CHATBOTS: Can a machine produce human-like behavior? The Turing test is whether a machine can be indistinguishable from a human in communication. As of 2008, no machine has passed the Turing test. Here are some machines that will talk to you with varying degrees of success in their similarity to human communication. Jabberwacky is a chatbot that won the “humanlike” Loebner prize from 2003 to 2006. ELIZA is an interesting comparison to Jabberwacky. While Jabberwacky learns from talking to users - expanding knowledge on its own, Eliza identifies patterns in the input from the user and matches them to rules in templates provided by a programmer (see Sood essay).
KISMET: Kismet is a robot at MIT who communicates non-verbally and quite effectively. Kismet perceives a variety of natural social cues from visual and auditory channels, and delivers social signals through gaze direction, facial expression, body posture, and vocal babbles.
ROBOTICS: This is a bar-balancing robot who learns to balance a bar over ten trials