Introduction to Cognitive Science:

Final Exam

Jonah Bossewitch

Cog 200

Professor Philip Johnson-Laird

January 17, 1994

According to Marr and Nishihara's theory of vision, an image is processed by a number of algorithms in order to create a mental model. Warrington and her associates have also established a double disassociation between the mechanisms for perceiving form and function. It is clear that for the brain to solve the inverse optics problem of vision it must be cheating by using a few tricks (i.e. constraints). Somewhere in this bag of tricks lies the explanation for the phenomenon that Gunnar Johansson observed.

"Johansson found that in a dark room, tiny lights fixed only to the major joints of a person are sufficient to enable observers to perceive a person walking even though nothing is visible except the trajectory of the lights." Any algorithm that claims to model human perception must be able to predict (or at least explain) this phenomena. In conjunction with the bottom-up processing that maps a 2-dimensional matrix of light intensities to a mental model, a top-down process constrains the bottom-up algorithm by narrowing down the plausible possibilities based on prior knowledge. In recognizing objects, especially objects in motion, Marr and Nishihara hypothesize a hierarchical organization of shapes that objects are decomposed into. It is reasonable to assume that the tremendous amount of information that the eyes take in needs to be grouped before it can be interpreted. In other words categorization must precede recognition.

If this theory is correct, namely that the visual system takes as input a 2-dimensional array of light intensities and processes them through a number of steps to create a mental model it is also reasonable to hypothesize a corollary. If some if the processing is done artificially for the brain, the brain will be able to continue where the artificial processor left off provided that the artificial processing is done in the same way that the brain would have. To draw an analogy, imagine somebody who wants to have a roll of film developed, and let us also imagine that film is developed. He brings his roll of film to a Fotomat and they begin to process his film using their patented 5 step process. Unfortunately the store burns down, but luckily for our hero the firemen manage to save his film. The film is up to step three in the processing, so Bill brings his film into a Kodak store and ask them if they can finish developing the film. The man behind the counter gently explains to Bill that once the processing has been initiated it must be finished by a Fotomat developer, since here at Kodak we use a seven step process that is incompatible with theirs.

The Johansson effect suggests that it is correct to think of the recognition algorithm as the method of film developing. Doing so would explain the results of the experiment as well as suggest testable predictions. Watching a person in a dark room with lights attached to their joints is like developing a roll of film that has already been partially developed. At some point in the processing of a man walking in well lit room the algorithms reduce the image to the equivalent of a walking in a dark room with lights on his joints. This also explains why subjects failed to recognize a man with lights on his limbs. This input is not a step that the brain would have processed the image through and is equivalent to expecting Kodak to finish developing the Fotomat roll.

Further experiments that might confirm this hypothesis include independently confirming that recognition takes the image through a step which resembles lights on joints. After this hypothesis is confirmed it could then be used to itself to verify other steps in the recognition process. If a hypothesized step is actually one of the ones used in recognition, then a subject given that step as input should be able to continue the processing where that step left off.

President Harold Shapiro

Is often considered a hero.

When it comes to weed,

He smokes when in need.

The definition of a clerihew, a 4 line humorous poem about a famous person, leaves alot of room for interpretation. Aside from the leeway that the word 'humorous' offers, there are no explicit constraints placed on the number of syllables per line. The rhythm of the poem is determined by the first and third lines of the poem and need not be the same number of syllables as the poems in the example.

In creating this poem I used a top-down algorithm since I knew that I could fill in the rhythm with one syllable words that did little to alter the semantic content of the poem. I first tried to come up with a theme for the poem in a very general sense. Using the example as a constraint I decided to write a poem that was humorous for one of the same reasons that the Russel poem is. I wanted to introduce a prominent, well respected personality and surprise the reader with something shocking in the second half. With this goal in mind I chose the President of the University, Harold T. Shapiro to be the "victim" of my joke. I then tried to think of something that no respectable individual in our society can admit to. While walking along in the snow near the Student Center, an image of President Shapiro smoking marijuana entered my consciousness and I instantly knew I was definitely going to answer problem 4 on the final exam. Once I had the idea, implementing it in a clerihew was trivial. I first needed to find a word that rhymed with Shapiro, and performed a mental search until I found (in memory) the word 'hero'. From that point I immediately formed the first two lines in my head and decided that I had fleshed out the first half sufficiently for now. I then tried to figure out how to fit drug use into the second half of the poem, and played with a couple of variations on the theme until I came up with the one above. The words weed, dope, joint, bong, high, and marijuana all were candidates for the last word of the third line so I tried thinking of words that they rhyme with to decide which one to use. Fitting the words to the meter once I had decided how to end the line was simply a matter of playing with a few combinations of one syllable words like 'one', 'who', and 'in'. The result, while not the most eloquent, metaphorical, piece of work demonstrates an effective algorithm that can be used to create other clerihews.

The mental process that I went through to create this clerihew seemed natural to me, although I was attempting to observe myself create and this may have altered my natural creative process. The trickiest part about generalizing an algorithm for creating clerihews is twofold. First, the algorithm must call a routine that determines whether or not a clerihew that it comes up with is funny or not. Second, the algorithm must have access to a knowledge base from which it can create attempts at humor from. Given these two components, it can then follow an algorithm similar to the one described above to create its own clerihews.

I have just finished reading a copy of "The Language of Emotions: An Analysis of a Semantic Field" (Johnson-Laird and Oatley, CSL Report 33, September 1988) and I will answer question 5 by responding to that paper.

First of all, I am not convinced that conscious individuals ever experience basic emotions. It seems that any basic emotion can develop a complex component that corresponds to consciousness imagining the self in that basic emotional state. This fact does not really have any consequences for your theory since you fit complex emotions into the five modes as well. However, I don't really understand what you mean by a basic emotion. Perhaps animals (and humans) devoid of consciousness experience emotions in that sense?

Second of all, I think that I may have thought of an emotion that can not be decomposed into the five modes. I am not sure if American English/Culture has the concept that I am referring to, but in Hebrew it is called Ta'hore (rhymes with galore) and it's antonym is Ta'may (rhymes with flambe'). The rough translation of these concepts is ritual purity and ritual impurity, but I am not sure if that truly captures their meaning. There are two types of ritual impurity: ritual impurity from contact with the dead or anything else that is ritually impure, and ritual impurity from menstruation (for women) and ejaculation (for men). Ritually impure individuals were forbidden from entering the temple and forbidden from having sexual intercourse. A ritually impure individual contaminates another object (only certain types of objects can be contaminated) by touching it and anybody else who touches a contaminated object also becomes impure. Purification consists of ritual immersion (in a meek'va) followed by sprinkling with the ashes of a red cow (only for death impurity).

It might be difficult to imagine what the words Ta'hore and Ta'may really meant to people living in those cultures (although the laws of Taharat Mishpacha or family ritual purity are still observed by Orthodox Jews). I also think that these two words pass the Clore test for emotions, namely that "feeling Ta'hore" and "being Ta'may" both seem to mean something. I am also unsure if these concepts can be grouped in any of the basic modes (happiness, sadness, fear, anger, disgust, desire). I am certain that people living in those times experienced feeling pure after ritual immersion. It is also unclear that the concept of purity is necessarily a complex emotion. It might reflect the sense of physical well being, or just plain feeling healthy. Perhaps there is a connection here with the Eastern concept of Lifeforce of which I know little about. I hope that this digression onto purity was an appropriate answer to this question.

I pledge my honor that my consciousness did it's utmost to intentionally insure that I did not violate the honor code in writing this paper.

Jonah Bossewitch

307 Forbes College

Princeton University