Frank Rosenblatt

Dr. Frank Rosenblatt, 1928-1971

PhD Experimental Psychology, Cornell, 1956 Developed neural networks called perceptrons

A probabilistic model for informationstorage and organization in the brain Key properties

Association or learning Generalization to new patterns Distributed memory Biologically plausible brain model

Cornell Aeronautical Lab (1957-1959), Cornell (1960-71)

Frank Rosenblatt

Dr. Frank Rosenblatt

Wikipedia portrayal exaggerated“Rosenblatt was a colorful character at Cornellin the early 1960s. A handsome bachelor, he drove a classic MGA sports car and was often seen with his cat named Tobermory.”

Those who knew him would consider him a rather shy genius and more of a Renaissance man Renaissance man because he excelled in a wide variety of subjects, including psychology (his original field), computing, mathematics, neurophysiology, astronomy, and music

Frank Rosenblatt

Agenda

The Mark I Perceptron – Visual System Model The Tobermory Perceptron – Auditory System

Model Perceptron Computer Simulations Rosenblatt's Book Rosenblatt-Minsky Debates and Minsky-Papert

Book Rat Brain Experiments Hobbies – Astronomy, Climbing, Music, Sailing Untimely Death

Frank Rosenblatt

The Mark I Perceptron Visual system model and pattern

classifier

Typical three-layer perceptron: fixed S→A and variable A→R connections

Examining A-unit of Mark I

Frank Rosenblatt

The Mark I PerceptronVisual system model and pattern

classifier

Input (sensory) layer of 400 photosensitive units in a 20x20 grid modeling a small retina

Connections from input to association layer altered through plug-board wiring, but once wired they were fixed for the duration of an experiment

Association layer of 512 units (stepping motors) each of which could take several excitatory and inhibitory inputs

Connections from association to output layer were variable weights (motor-driven potentiometers) adjusted through error-propagating training process

Output (response) layer of 8 units

Frank Rosenblatt

The Tobermory PerceptronAuditory system model and pattern

classifier

Named after talking cat, Tobermory, in story by H.H. Munro (aka Saki) Large machine

S-units: 45 band-pass filters and 80 difference detectors

A-units: 1600 A1-units (20 time samples per detector) & 1000 A2-units

R-units: 12, with 12,000 adaptive weights A2→R-units.

Frank Rosenblatt

Perceptron Computer Simulations

Hardware implementations made good demonstrations but software simulations were far more flexible

In early 1960s these computer simulations required machine language coding for speed and memory usage

Simulation software package – user could specify the number of layers, the number of units per layer, type of connections between layers, etc.

Computer time at Cornell and NYU

Frank Rosenblatt

Rosenblatt's BookPrinciples of Neurodynamics,

1962

Part I: historical review of brain modeling approaches, physiological and psychological considerations, and basic definitions and concepts of the perceptron approach

Part II: three-layer, series-coupled perceptrons –mathematical underpinnings and experimental results

Part III: multi-layer and cross-coupled perceptrons Part VI: back-coupled perceptrons Book used to teach an interdisciplinary course

"Theory of Brain Mechanisms" that drew students from Cornell's Engineering and Liberal Arts colleges

Frank Rosenblatt

Series-Coupled Perceptrons

A perceptron is a network of sensory (S), association (A), and response (R) signal generating units

A series-coupled perceptron is feed-forward S→A→R An elementary perceptron is a series-coupled

perceptron with one R-unit connected to every A-unit and fixed S→A connections

Convergence Theorem: Given elementary perceptron, stimulus world W, and any classification C(W) for which a solution exists, then if all stimuli in W re-occur in finite time, the error correction procedure will always find a solution

Frank Rosenblatt

Series-Coupled PerceptronsMark I was typical S→A→R perceptron

ConnectionsS→A: fixed, usually localA→R: adjustable w training

Frank Rosenblatt

Series-Coupled PerceptronsA-units usually local biologically-plausible

detectors

Frank Rosenblatt

Series-Coupled Perceptrons

Dotted lines are variable connections

Rosenblatt studied three and four-layer series-coupled perceptrons with two sets of variable weights but was unable to find a suitable training procedure like back-propagation

Frank Rosenblatt

Cross-Coupled Perceptrons

A cross-coupled perceptron is a system in which some connections join units of the same type (S, A, and/or R)

Frank Rosenblatt

Back-Coupled Perceptrons A back-coupled perceptron is a system with feedback

paths from units located near the output end of the system to units closer to the sensory end

Frank Rosenblatt

Rosenblatt-Minsky Debates

and Minsky-Papert Book

Rosenblatt and Marvin Minsky (MIT) debated at conferences the value of biologically inspired computation, Rosenblatt arguing that his neural networks could do almost anything and Minsky countering that they could do little

Minsky, wanting to decide the matter once and for all, collaborated with Seymour Papert and published a book in 1969, Perceptrons: An Introduction to Computational Geometry, where they asserted about perceptrons (page 4), "Most of this writing ... is without scientific value...”

Minsky, although well aware that powerful perceptrons have multiple layers and Rosenblatt's basic feed-forward perceptrons have three layers, defined a perceptron as a two-layer machine that can handle only linearly separable problems and, for example, cannot solve the exclusive-OR problem

Frank Rosenblatt

Minsky-Papert BookH.D. Block’s response paper

The authors address three classes of readers1. Computer scientists specializing in pattern recognition, learning

machines, and threshold logic2. Abstract mathematicians interested in the debut of Computational

Geometry3. Those interested in the general theory of computation leading to

decisions based on the weight of partial evidence, e.g. psychologists and biologists

H.D. Block concludes1. Computer scientists “will find the book of little value”2. Abstract mathematicians consulted “were not captivated”3. “For psychologists and biologists, the level of mathematical

maturity demanded will, I believe, make the book somewhat difficult to read.”

Frank Rosenblatt

Rat Brain Experiments Late 1960s – Rosenblatt began experiments

in the Cornell Department of Entomology on the transfer of learned behavior via rat brain extracts

Rats were taught discrimination tasks such as Y-maze and two-lever Skinner box, their brains extracted and injected into untrained rats that were then tested in the discrimination tasks to determine whether or not there was behavior transfer from the trained to the untrained rats

Rosenblatt spent his last several years on this problem and showed convincingly that the initial reports of larger effects were wrong and that any memory transfer was at most very small

Frank Rosenblatt

Astronomy

Rosenblatt built a modest observatory on a hilltop behind his house 6 miles east of Ithaca. Work began summer 1961, Fecker 12" cassegrain telescope.

He had interest in SETI (Search for Extraterrestrial Intelligence), wrote a proposal touting a "Stellar Coherometer” he designed, and was awarded $75K for the project.

The observatory was completed about 1966 – a circular cinderblock structure with dome housing the telescopeCurrent photo – house in

background

Frank Rosenblatt

Music

Rosenblatt was an accomplished pianist and had a grand piano at his house in Brooktondale

He played the well-known classical pieces of Mozart, Beethoven, etc.

He also composed music and had a penchant of improvising endlessly on "Three Blind Mice"

Frank Rosenblatt

Practical Joker As a graduate student

Frank was a psychology major and Prof. James Gibsonwas a well-known faculty member and Frank’s dissertation advisor. As the story goes, Frank and someother graduate students drove to the town of Gibson one night and stole the town's "Gibson" signs, which they then mounted at the door of Professor Gibson's office.When Department Chair saw the signs, he remarked to the department secretary, "Don't you think Gibby's getting a little ostentatious?“

Traveling to a conference Frank remarked“Do you think McCulloch sleeps with his beard under or over the covers?”

Frank Rosenblatt

Rosenblatt – Renaissance man

Excelled in a wide variety of subjects – psychology (his original field), computing, mathematics, neurophysiology, astronomy, and music

He had two research reputations neural networks with his perceptron work neurophysiology with the rat brain experiments

When learning a new subject (to paraphrase Rodman Miller)

In a few weeks he knew a little In a few months he knew a great deal Soon thereafter he was discussing topics with experts in the

field

Frank Rosenblatt

Untimely Death Sailboat accident on his 43rd birthday

He “was a most gifted human being ... had made his entire life a contribution to mankind”

Congressional Record