physics

Haldan Keffer Hartline

Haldan Keffer Hartline is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Haldan Keffer Hartline rather than just read about it. In short: Haldan Keffer Hartline (December 22, 1903 – March 17, 1983) was an American physiologist who was a co-recipient (with George Wald and Ragnar Granit) of the 1967 Nobel Prize in Physiology or Medicine for his work in analyzing the neurophysiological mechanisms of vision. Biography Haldan Hartline did his undergraduate studies at Lafayette College in Easton, Pennsylvania, graduating in 1923.

Key takeaways

Haldan Keffer Hartline belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Haldan Keffer Hartline to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Haldan Keffer Hartline from memory before moving on to harder problems.

Reference excerpt

Haldan Keffer Hartline (December 22, 1903 – March 17, 1983) was an American physiologist who was a co-recipient (with George Wald and Ragnar Granit) of the 1967 Nobel Prize in Physiology or Medicine for his work in analyzing the neurophysiological mechanisms of vision.

Biography Haldan Hartline did his undergraduate studies at Lafayette College in Easton, Pennsylvania, graduating in 1923. He began his study of retinal electrophysiology as a National Research Council Fellow at Johns Hopkins School of Medicine, receiving his medical degree in 1927.

Scientific career After attending Leipzig University and the Ludwig-Maximilians-Universität München as an Eldridge Johnson traveling research scholar from the University of Pennsylvania, he returned to the US to take a position in the Eldridge Reeves Johnson Foundation for Medical Physics at Penn, which was under the directorship of Detlev W. Bronk at that time. In 1940–1941, he was Associate Professor of Physiology at Cornell Medical College in New York City but returned to Penn and stayed until 1949. Then he became professor of biophysics and chairman of the Jenkins Department of Biophysics at Johns Hopkins University in 1949. One of Hartline's graduate students at Johns Hopkins, Paul Greengard, also won the Nobel Prize. Hartline joined the staff of Rockefeller University, New York City, in 1953 as professor of neurophysiology. Hartline investigated the electrical responses of the retinas of certain arthropods, vertebrates, and mollusks, because their visual systems are much simpler than those of humans and thus easier to study. He concentrated his studies on the eye of the horseshoe crab (Limulus polyphemus). Using minute electrodes, he obtained the first record of the electrical impulses sent by a single optic nerve fibre when the receptors connected to it are stimulated by light. He found that the photoreceptor cells in the eye are interconnected in such a way that when one is stimulated, others nearby are depressed, thus enhancing the contrast in light patterns and sharpening the perception of shapes. Hartline thus built up a detailed understanding of the workings of individual photoreceptors and nerve fibres in the retina, and he showed how simple retinal mechanisms constitute vital steps in the integration of visual information.

Awards and honors In 1948, Hartline was elected to the United States National Academy of Sciences. He was elected to the American Philosophical Society in 1952 and the American Academy of Arts and Sciences in 1957. He was elected to the inaugural class of Fellows of the Optical Society (OSA) of America in 1959. Later, OSA elected him an Honorary Member in 1980. Hartline was elected a Foreign Member of the Royal Society (ForMemRS) in 1966. He was awarded the Nobel Prize in Physiology or Medicine in 1967.

Personal life Hartline married Elizabeth Kraus Hartline in 1936. They had three children: Daniel, Peter, and Frederick Hartline.

References

External links Keffer Hartline on Nobelprize.org

Illustrations

Worked examples

Example 1 — a first encounter with Haldan Keffer Hartline

Start with the simplest possible case. Write down what Haldan Keffer Hartline claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Haldan Keffer Hartline before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Haldan Keffer Hartline ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Haldan Keffer Hartline

In research: Haldan Keffer Hartline appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Haldan Keffer Hartline in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Haldan Keffer Hartline is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1903 births, 1983 deaths, 20th-century American physicists, so understanding it makes those chapters shorter.
In everyday life: Look for Haldan Keffer Hartline outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Haldan Keffer Hartline in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Haldan Keffer Hartline means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Haldan Keffer Hartline out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Haldan Keffer Hartline in simple terms?

Why does Haldan Keffer Hartline matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Haldan Keffer Hartline?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Haldan Keffer Hartline.