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
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
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
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
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
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
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.
The orginal demonstration, developed by Daniel Simons at University of Illinois, illustrates inattentional blindness. Be sure the video has completely downloaded before you start it. If the video stops to download you will lose the effect. There are two teams of students passing a basketball, a team with white shorts and a team with black shirts. Count how many passes are made by the team of white shirts. Did you see anything unusual? If not, try again counting the passes by the black shirts. Inattentional Blindness
Do senses deceive? Descartes questioned the veracity of the senses and this question has motivated an important area of cognitive science. These demonstrations show how the mind adds to sensory input yielding some startling experiences. Note that although the sensory input is constant, the perception changes depending on such factors as context, eye movements or to-be- identified factors.
MEMORY TEST: This demonstration tests digit span (a measure of short-term memory), sentence span (a measure of working memory), delayed memory (a measure of long-term memory), change blindness, binding of context and features to objects, and prospective memory (the ability to remember to do something in the future). After the tests, scores are presented and the various tests are explained. Memory
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. Mental Rotation
VERBAL TRANSFORMATION EFFECT: In the Verbal Transformation Effect the same word is repeated many times and different words may be heard even though the sensory stimulus is unchanged. Verbal Transformation
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. Play McGurk
CATEGORICAL PERCEPTION Categorical
TURING MACHINE: (see Sood essay). The Turing Machine is a model of computation that students often find hard to grasp from lecture and discussion alone. To allow students to build, simulate and experiment with Turing Machines, the JFLAP software is quite useful. It is available for free download here: http://www.jflap.org/, with a nice tutorial on how to use it here: http://www.jflap.org/tutorial/. The software allows users to save Turing Machines they build, and interact with Turing Machines that others have built. For a simple Turing Machine demonstration, use JFLAP to open <palindrome.jff> and you’ll find a Turing Machine that accepts all strings composed of ‘a’s and ‘b’s which are palindromes. Additionally, use JFLAP to open <eq1s0s.jff> and you’ll find a Turing Machine that accepts all strings composed of ‘1’s and ‘0’s with an equal number of each. After opening a Turing Machine using JFLAP, you can provide it with sample input strings and slowly walk through the machines process of evaluating these strings. Turing Machine
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). Jabberwacky
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.