Monday 29 December 2014

An Introduction to Human Bias

Consider a pathway following an image formed by light leaving our subject.  It passes through a camera lens and is transformed into a digital camera image.  A human, viewing the image analyses it's content with care and uses an array of tools to validate a firm identification based on the available evidence.  This is the very pathway we are exploring throughout this blog.

All along this pathway there are parameters that can affect a favourable outcome - the correct identification of the bird in the image.  We have the composition of the image, consisting of the posture, angle of view and the terrain in which we find our subject. We have environmental considerations such as lighting, temperature, moisture, dust and pollution in the air.  We have the qualities of the lens and camera sensor and in-camera settings.  We have image processing parameters and the image viewing platform, be it the screen on the back of the camera, a computer or phone screen or a print.  The image has traveled a long way along our path...but we are only now beginning to ask what it is we are looking at. The remainder of the route to the identification of the subject from the photograph is strewn with an even greater array of complex parameters which we will collectively call human bias.

Up until now the blog has been devoted to reviewing the various parameters that go into creating a digital image.  I have also started looked at tools and methods for forensically analysing digital images, so that we can overcome some technical limitations and peer into the finer details of an image.  Along the way I have touched on certain aspects of the human condition, including aspects of the design of the human visual system.  I am now going to broaden this out to cover a much wider array of parameters relating to human vision and cognition.

The prevalence of human cognitive bias
Cognitive Science is a broad discipline looking at a whole range of fields relating to the human mind.  We don't often stop to consider the functioning of our own minds, how we receive and record sensory information, analyse and transform it into logical thought.  It probably goes without saying that this is of far more importance than any other when it comes to the actual identification of a bird.  Though the first bird identification software has started to emerge, when it comes to difficult bird identification puzzles it is probably safe to say we will always be totally reliant on human cognitive skills.  How much of our thought process is deliberate, objective and logical and how much is based on automation and subjective reasoning.  Well there seems to be growing evidence that a lot of our decision making is not logical at all, is based on hard-wiring, emotion and memory.

Take the following hypothetical scenario.  Three small birds fly past an experienced observer along a street in a busy city.  The observer raises a camera and takes one photograph of the three birds as they pass.  Before the observer has had a chance to check the camera, we ask the observer what the birds were and the answer is a confident "they were House Sparrows" (Passer domesticus).

We ask the observer to write a description detailing their observation.  The description is very simple and honest.  "Three birds flew past which were easily identified as House Sparrows.  There are always House Sparrows on this street.  The identification is based mainly on gestalt and on some detail observed on one of the males as seen through my camera lens as the lens focused on the subjects".  The observer says they are 100% confident of the identification (though quietly might like to check the photograph for total confirmation).  Writing the description, the observer remains confident though is somewhat more aware of the lack of strong evidence as they write.  There are a great many other species that could be involved.  The observer is mainly 'playing the odds'.

Though this is just a hypothetical scenario, we have probably all experienced this type of situation.  Cognitive bias sets us up for these fails all the time and it can take a lot of discipline to really learn from these simple experiences.  If the observer were being critical of their observation the correct answer would have been "I am certain one bird was a male House Sparrow as I observed it clearly enough to ID it properly.  The other two birds were not seen well enough to identify them correctly so I will leave them unidentified".  How many birders do we know who actually talk like that?  The fact is, life's experiences encourage us to learn and use short cuts or heuristics as we grow and develop...close enough is usually good enough.

There are many different biases at play in this example.  We have the observers prior experiences (curse of knowledge bias).  The observer has evaluated that, based on past experience, 'there are always House Sparrows and only House Sparrows on this street' (attentional bias/availability heuristic/availability cascade/belief bias/congruence bias/illusory correlation/levelling and sharpening effects).  In reality, the observation was too brief to make a firm judgement but this fact has been ignored.  The observer identified one House Sparrow so this appears to confirm the initial opinion (framing effect/anchoring bias/confirmation bias/decoy effect/illusory correlation/survivorship bias/insensitivity to sample size).  The observer possibly wasn't heavily invested in the observation so didn't take the time to look carefully enough or verify their initial assessment.  However, on being asked what the birds were the observer is now forced to become more invested in the event.  The opportunity for objective reason has been missed - instead the oberver digs their heels in (irrational escalation/overconfidence effect/optimism bias).  On being asked to prepare and consider a description, the observer might have felt some doubt creeping in, as there really wasn't a lot to go on to make a firm ID (choice-supportive bias).  There were a lot of inferences that needed to be made from the available evidence and the observer has either chosen to ignore that fact or filled in some of the gaps with false memory (including missatribution).

A photograph that might help clinch the ID is now presented.  The moment of truth.   The photograph confirms that there were in fact two male House Sparrows but the third bird was actually a male White-throated Sparrow Zonotrichia albicollis.  The observer remarks - 'A simple error, no biggy'.  'We all make mistakes right'?   Already the observer is moving on from the event, choosing to maintain the status quo in their cognitive pathways rather than challenge them (cognitive dissonance).

The example only serves to illustrate some of the underlying processes that might be going on during our thought processing.  These cognitive biases and heuristics should not be seen as an entirely negative thing.  After all, they underpin our daily lives and exemplify our incredible abilities to navigate life as independent, successful sentient beings.  But, if our goal is to analyse images in a entirely objective and unbiased fashion then we have to consider how stimuli can trigger certain automated responses and thought patterns, and it might help to find ways to circumvent them.

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