Essays on the use of information theory in biology

Essays on the Use of Information Theory in Biology: Associate Editors: Leroy Angenstine [and Others]. Front Cover. Henry Quastler. University of Illinois Press, .
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Information theory at the keyboard — Henry Quastler’s “Studies of Human Channel Capacity” (1956)

After all, the keen musicologist sees in such a demonstration the long history of keyboard pedagogy concerned with the perfectibility of performing bodies. On the other hand, the historian of communications technology sees something different: the lineage of chorded alphabetic keyboards that stretches back to the first stenographic typewriters in the middle of the nineteenth century. Since PianoText also depends on the measurement of both letter frequencies in the English language, as well as computing the note-transition probabilities in a representative corpus of tonal music, it also draws on the last 75 or so years of research into natural language processing and, even, the relatively new field of Music Information Retrieval.

In this paper, I suggest that speculative computing applications like PianoText are only thinkable when music and typewriting are both conceived of as a kind of information processing. This idea is many decades older than this demo. This particular attitude toward musicianship is the manifestation of an informaticized view of musical production that reaches back to the earliest applications of information theory, as transplanted outside of its original discipline of communications engineering. I point to research conducted in the first half of the s at the University of Illinois by Henry Quastler, which demonstrates this notion in action in the behavioral psychology laboratory.

Reporting on the results of his experiments, to which I will shortly describe in more detail, Quastler makes the following remarkable observation about pianism, using the terms of information theory:. Piano playing is a sequential task which involves high rates of information transmission.

A piano virtuoso generates information at a rate which is very impressive indeed; it is possible that that the performance of a piano player may approach the peak of human capability. Shannon pointed out that many problems in communications shared some common features: a transmitter, which sends messages in the form of signals over a channel that may or may not be subject to distortion, and a suitably equipped receiver apparatus which detects differences in the signals, resolving them into the original messages.

The word communication will be used here in a very broad sense to include all of the procedures by which one mind may affect another. This, of course, involves not only written and oral speech, but also music, the pictorial arts, the theatre, the ballet, and in fact all human behavior. The discovery and use of information, it must be pointed out, is not exclusively tied to the growth of computing.

In other words, information-theoretic conceptions of music need not be specified with respect to a particular computer system or artificial environment. The scientific conceptualization of information resulted from the consolidation of decades of research in electrical engineering, mathematical logic, physics, psychology, and neurobiology, all of which predated the design and manufacture of digital computers as we would recognize them today.

In , Quastler moved to the cornfields of Urbana where he practiced medicine until his appointment to a assistant professorship in physiology at the Control Systems Laboratory, in Though his name is probably unknown to the majority of music psychologists today, Henry Quastler was by no means a marginal figure in his field. The historian of science Lily Kay has credited Quastler with the introduction of concepts from information theory into molecular biology that have now become naturalized as commonplaces of the field.

By the time he was appointed to the Biological Systems Group, Quastler was very familiar with the work of Shannon and Wiener on communications. He saw fit to adjust his focus away from information-theoretical applications in molecular biology and instead on to human behavior considered at the macro-scale: the information-processing behaviors of individuals and organizations. A report from summarizes the work of the Biological Systems Group into four main strands:.

Information theory - Monoskop

This topic was of general interest to the growing community of psychologists who saw a useful quantitative tool in information as well as to military planners and industrial researchers, who were interested in computing the maximum capacities of technological systems that depended on human beings. With these assumptions in mind, Quastler developed a battery of activities that were designed to shed light on limits of human ability in terms of information transmission. He chose behavioral tasks that appeared to conform to three criteria.

First, all inputs should come from a single source: the task must be possible with reference to a single kind of stimulus, be it a dial, characters on a sheet to be transcribed, or in musical notation. This table summarizes the tests that Quastler carried out, the results of which are described in a series of unclassified reports, recently made available at the University of Illinois.


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The first group of columns shows the independent variables that were explored using in each task farming. As we will shortly see, the affordances of musical notation and skilled musical listeners allowed the experimenters to independently vary the speed, order of complexity, and range of motion used in stimuli. Not only did the tasks have to be on a par with real-world activities like reading radar displays or responding to air-traffic control commands, they also had to be comparable to each other.

Quastler seemed more certain that his experimental results reflected some empirical reality when his putative channel capacity calculations agreed with each other across a variety of modalities. The appearance of this unit, of course, prefigures its use today to measure data in storage and in transit in actual computer systems.

The validity of this research, Quastler admitted, hinged on assuming that these specialized behaviors were in some way commensurate with the other activities that his military stakeholders were interested in. It is a vision of pianism that is departicularized, studied from a point of view that looks through the contingencies of musical expertise: a flattened view that considers musical performance as just another skilled activity—like typing.

Lecture 1: Introduction to Information Theory

There is a caveat, of course: not all of these upper limits can be interpreted as channel capacities. In all examples, the notes are selected according to uniform distribution over a set of possible keys of the piano: in each stimulus type, each note has equal probability of occurring, with no conditional dependencies between successive notes.

What Quastler would argue to be the information content of an individual note in the stimulus is therefore proportional to the size of the total set of possible pitches in each stimulus.


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  • The notes played were intended to be strictly isochronous and of equal duration, but the example passages show some a mismatch between the notation and the intended stimulus. Quastler justifies the use of randomly-generated sequences of pitches in his experiment by describing how the musician learns both specific pieces and a sense of musical style in terms of information acquisition. However, Quastler concedes that determining how much old information the subject actually uses is difficult to evaluate. Quastler concludes this confound means that an experiment making use of an already-learned piece or a piece in a familiar style cannot be used to measure the pianists information processing capacity.

    Quastler thus proposes the following solution:. One can get around this problem by setting up experimental situations in which all the information in the text is new. This certain to be the case when the script used is a random sequence of notes.

    Such a script is easily made up with the help of a table of random numbers. In this situation there is no doubt about the information input. The apparent richness of visual input, when viewed as data, suggests that humans can ingest information much more quickly than it appears to be able to process it. Quastler explains:. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

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    Sign up to take part. A Nature Research Journal. This is attempted by recourse to the example of a codfish laying a million eggs the entropy content of whose genomes shows a normal distribution about a mean value in accordance with the second law of thermodynamics.

    On one tail of this distribution curve will be a small percentage of eggs with an entropy content equal to or less than that of the parents. What follows in Campbell's communication is unexceptionable provided that this sentence is true.

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    It is at this point that the author merely evades one of the most important questions at issue in the earlier correspondence 2—4. The genome may be regarded as a series of DNA molecules functioning as templates. The thermodynamic entropy content of these molecules is a function of the arrangement of the atoms, conventionally expressed as k. A single alteration in the relative positions of adjacent nucleotide bases could convert a crucial part of the genome code to nonsense so that its capacity to support development was lost, but this could occur without an increase, indeed even with a decrease, in the thermodynamic entropy content of the genome molecules 5.

    Stated in a more general way, this is the problem of the relationship between the amount of developmentally meaningful organization in the genome we will call this the information content and its entropy content. There are two problems here: first, the definition and quantization of the information content of the genome and, second, the nature of its relationship to the thermodynamic entropy content.

    One avenue of enquiry which offers hope in this situation would seem to be the information theory analogy. Campbell, B. Popper, K. Buchel, W. Woolhouse, H. Lwoff, A.

    References

    Szilard, L. Shannon, C. Brillouin, L. Academic Press, New York, Carnap, R. Linschitz, H. Download references.