Hindsight Bias: An Ovine Survey

“What started as a joke has become a research exercise based on the question: ‘How do sheep send messages to one another in this digital age?’”

https://depositphotos.com/17165943/stock-photo-sheep-and-lambs.htmlThe arrival of a U.S. Patent and Trademark Office (USPTO) office action citing no less than six earlier patents directed to various sub-combinations in the features of the main independent claim in an application which I was handling prompted the present note.

Readers may recall the decision of Judge Rich In re Winslow 365 F.2d 1017 (C.C.P.A. 1966):

We think the proper way to apply the 103-obviousness test to a case like this is to first picture the inventor as working in his shop with the prior art references — which he is presumed to know — hanging on the walls around him.

However, Boltzmann’s entropy formula S = k log W where S represents entropy, a concept associated with a state of disorder, randomness, or uncertainty, and W represents the number of possible states in the relevant system, leaves an unforgettable impression on those who have studied it. Even if the fields from which the earlier patents might be selected are restricted to relevant general classifications, the number of combinations of six references which might have been collected together from the body of prior art in the relevant technical field randomly and without knowledge of the invention is mind-boggling.

Even then, a small amount of purposeful prior art redesign by the examiner was needed to arrive at the full set of features claimed.

In contrast, the warnings against hindsight in the USPTO Manual of Patent Examining Procedure at 2141 and 2145 are relatively brief, and it is difficult to conclude that examiners take them seriously.

Hindsight Bias in Literature and Life

Credible warnings can be found in literature. Arthur Conan Doyle illustrates the problem by the following exchange between Sherlock Holmes, Dr Watson and a visiting client Jabez Wilson in “The Red-Headed League”:

“Beyond the obvious facts that he has at some time done manual labour, that he takes snuff, that he is a Freemason, that he has been in China, and that he has done a considerable amount of writing lately, I can deduce nothing else.”

Mr. Jabez Wilson started up in his chair, with his forefinger upon the paper, but his eyes upon my companion.

            “How, in the name of good-fortune, did you know all that, Mr. Holmes?” he asked. “How did you know, for example, that I did manual labour. It’s as true as gospel, for I began as a ship’s carpenter.”

            “Your hands, my dear sir. Your right hand is quite a size larger than your left. You have worked with it, and the muscles are more developed.”

            “Well, the snuff, then, and the Freemasonry?”

            “I won’t insult your intelligence by telling you how I read that, especially as, rather against the strict rules of your order, you use an arc-and-compass breastpin.”

            “Ah, of course, I forgot that. But the writing?”

            “What else can be indicated by that right cuff so very shiny for five inches, and the left one with the smooth patch near the elbow where you rest it upon the desk?”

            “Well, but China?”

            “The fish that you have tattooed immediately above your right wrist could only have been done in China. I have made a small study of tattoo marks and have even contributed to the literature of the subject. That trick of staining the fishes’ scales of a delicate pink is quite peculiar to China. When, in addition, I see a Chinese coin hanging from your watch-chain, the matter becomes even more simple.”

            Mr. Jabez Wilson laughed heavily. “Well, I never!” said he. “I thought at first that you had done something clever, but I see that there was nothing in it after all.”

Credible warnings can also be found in real life. In her book entitled “The Challenger Launch Decision”, University of Chicago Press, 1996, Professor Diane Vaughn explains that:

Turner, in Man-made Disasters, notes the tendency for a problem that was ill-structured in an organization to become a well-structured problem after a disaster, as people look back and reinterpret information ignored or minimized at the time, that afterward takes on new significance as signals of danger. After the Challenger incident, the SRB joint problem became a well-structured problem as the tragedy made salient and selectively focused attention on the NASA decisions that seemed to lead inexorably to it. The information then was strung together in post-tragedy accounts that presented a coherent set of signals of potential danger that was not characteristic of the situation as it existed for NASA and Thiokol managers and engineers in the work group prior to the tragedy. Furthermore, even the most detailed of these post-disaster accounts extracted actions from their historical and organizational context in a stream of actions, the sequence of events and structures of which they were a part. Robbed of the social and cultural context that gave them meaning, many became hard to understand, controversial and, in some cases, incriminating. The result was a systematic distortion of history that obscured the meaning of events and actions as it existed and changed for the participants in the situation at the time the events occurred. (emphasis in the original).

The hindsight fallacy can be verified in my personal experience. What started as a joke has become a research exercise based on the question: “How do sheep send messages to one another in this digital age?”

The many people that I have asked over a period of years range from individuals with an interest in computers to others who work at supermarket check-outs. Not a single person in some years of telling this joke has ever been able to guess the answer, either immediately or with gentle prompting.

The answer, of course, is that the sheep use baa code.

An individual trained in the manner of thinking characteristic of examiners in the USPTO and elsewhere would regard the answer as obvious. Children are taught at an early age the sound that sheep make and will have routinely observed sheep making such sounds during their childhood. Today, almost everything we purchase carries a bar code, and those on check-outs handle such items all day every working day. Given this fact pattern, surely it is straightforwardly obvious to translate bar code for humans to baa code for sheep. Following the reasoning of Justice Kennedy in KSR v. Teleflex 550 U.S. 398 (2007), the answer flows from “recourse to common sense” to which recourse should not be denied by rigid preventative rules. However, when you ask the question of real people, the question creates puzzlement and real people simply cannot make the link even when they are reminded that the sound a sheep makes is a baa.

Let’s Not Wait for Hindsight to Address the Problem

A search through the European Patent Office (EPO) decisions database under art. 56 EPC revealed approximately 25,200 issued decisions, but if the keyword “hindsight” is added the total shrinks to 45. Thus, in both the United States and Europe, it is arguable that the need to avoid hindsight bias deserves greater attention than it is currently given.

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Join the Discussion

12 comments so far.

  • [Avatar for Paul Cole]
    Paul Cole
    November 29, 2021 04:31 am

    @ Anon

    Many thanks for drawing attention to the work of Philip K. Dick, one of the outstanding science fiction authors, and to the later work of Ridley Scott who turned it into an outstanding film.

    I hope that you found this a ewesful paper.

  • [Avatar for Paul Cole]
    Paul Cole
    November 29, 2021 04:23 am

    @ Particularly Pointing Out

    The problem is that when Mr Jabez Wilson knew Sherlock Holme’s chain of reasoning, there was no way he could put it out of his mind and he could not return to his former mental state. In exactly the same way, the examiners know the answer to the problem addressed by the inventor. Hence in the case I was referring to there were assembled SIX prior art references, which did not take the examiner quite there, so he had to do a little bit more redesign of his own to fully arrive at the claimed subject-matter. The point is that you will not be either motivated or enabled to gather the knowledge until you know the invention, so a degree of caution in formulating these objections is appropriate.

    As Christmas is approaching and we have been discussing sheep, think what Scrooge the Ram woudl say: Baa humbug!

  • [Avatar for Anon]
    November 28, 2021 08:14 pm


    Are you speaking as an examiner?

  • [Avatar for Particularly Pointing Out]
    Particularly Pointing Out
    November 27, 2021 05:34 pm

    it must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant’s disclosure, such a reconstruction is proper. (MPEP 2145(X)(A)), quoting In re McLaughlin, 443 F.2d 1392, 170 USPQ 203 (CCPA 1971)).

    Examination of claims is 1000% based on hindsight. It’s the way examiners are taught to examine applications. The prior art search is based on the language used in the claims and the examiner uses the specification to reconstruct the claims using the prior art.

  • [Avatar for Moderate Centrist Independent]
    Moderate Centrist Independent
    November 27, 2021 04:46 pm

    American accent? Which one?
    The joke works well with a New England accent, more Maine or Vermont but South Boston might do.

  • [Avatar for Peter Kramer]
    Peter Kramer
    November 27, 2021 12:10 am

    A problem that has emerged post KSR is that so-called “rigid” criteria of TSM had led to decisions such as In re Gorman, wherein numerous references with explicit teachings or suggestions could be cited to make an “obvious” combination. However, post KSR, I think it’s doubtful that the Gorman holding,
    which was premised on TSM should be relevant, and the matter of the number of references and how many of them lack explicit teaching or suggestion should be revisited by the Fed. Cir.

  • [Avatar for Pro Say]
    Pro Say
    November 24, 2021 05:32 pm

    Hindsight bias reaches into the past to steal the future.

    Stop stealing the future.

    Just stop it.


  • [Avatar for B]
    November 24, 2021 04:47 pm

    “What started as a joke has become a research exercise based on the question: ‘How do sheep send messages to one another in this digital age?’”

    Twitter, obviously

    @ American Cowboy “By the way, Paul, the “bar” vs “baa” joke works much better with an English accent than an American accent.”

    Long Islanders disagree

  • [Avatar for MaxDrei]
    November 24, 2021 12:22 pm

    Paul, do we need to distinguish between “hindsight” and “ex post facto analysis”? I ask because the reality is that every Examiner, every judge, every jury member, inevitably already has knowledge of the invention by the time they are called upon to assess its obviousness Y/N. They can’t help but do that assessment with hindsight knowledge of the invention, can they?

    And if that is inevitably so, what they we do to help them exclude ex post facto analysis from their obviousness determination (like resorting to their commonsense to settle the issue). How to avoid ex post facto analysis? How about using a rigorous, methodical and prescriptive TSM approach? Might that work? It seems to, at the EPO.

  • [Avatar for American Cowboy]
    American Cowboy
    November 24, 2021 11:36 am

    Oh, lord yes, examiners use hindsight WAY too much, and do not seem to pay any price for doing so.

    By the way, Paul, the “bar” vs “baa” joke works much better with an English accent than an American accent.

  • [Avatar for Anon]
    November 24, 2021 09:35 am

    The beginning of the article set off a stream of neuron firings that resulted in:

    Do Androids Dream of Electric Sheep?

    So Bladerunnery…