Archive for the ‘Human Factors history and studies’ Category

Nagoya Experiment – drivers are bad followers

October 27, 2016 Leave a comment

When we are asked to follow another car at a constant speed we tend to make little variations in speed rather than driving at a constant speed. Those variations can initiate brake reactions in drivers following us, and then drivers following them – a wavelike proceed of the brake reaction that can initate a traffic jam for no reason. Mathematical this behaviour is can be described similar to a damper, two waves influencing a third wave. One wave describes the acceleration/deceleration of the lead driver, another wave the acceleration / deceleration of the following driver, those both waves influence the acceleration / deceleration of the traffic behind those cars (described by the third wave). How easy and fast, within a couple of seconds, that can happen you can see in the video below. The study behind the video was conducted by Prof. Sugiyama from Nagoya university. Drivers were asked to drive in a roundabout with constant speed, following other drivers. There occur traffic jams for no reason after a couple of seconds.

Connected car technology might be able to limit the proceeding of traffic jam shockwaves such as in the video by informing drivers about variations in traffic seconds before the drivers notices a behaviour change in their lead cars (e.g. Fuchs et al.). Such system feedback might be “too late” to help drivers driving directly behind the lead vehicle as the lead car’s system needs time to recognise and communicate the braking event to the other cars, but it could help the driver behind that car. Another variable to consider is how drivers react to such a system feedback, if the system feedback could / should include guidance for the response – e.g. recommending the driver to decrease to a certain speed to keep in flow to avoid too harsh braking. Harsh braking might result in the next shockwave and should be avoided. Research in car-following behavior is not new, e.g. Ranney discusses car-following models in his paper from 1999 or by Panwai et al. in 2005, rather “rediscovered” in course of higher automated vehicles and connected cars.

Another interesting aspect is the personal distance that a driver prefers and keeps to other cars for hisher feeling of safety. It is something indivdual, depending, e.g. on personality and driving style. However, in dense traffic drivers maybe forced to keep smaller distances. The driver needs to satisfice between the safety levels that the he/she wants to keep and getting with the traffic, e.g. if the traffic density is high and the driver would keep a longer safety distance to the car in front this longer gap could be used by other drivers to move in. IF the safety distance is reduced, does this then influence how drivers react to braking of a lead vehicles? How would they react if the system provides a suggestion for a certain speed, would they follow the suggestion?

New Scientist

Fuchs et al.

Panwei and Dia

How good do you think you remember a well known Logo?

March 13, 2015 1 comment

There is an amount of brands we see everyday, just think of Apple, Coca Cola, BMW and Audi. How good do you think you remember their logo? Does it sound like an easy task?
Companies invest a lot of money on a good perceivable and memorable logo and aim to spread their logo into the last corner of the world. Regular exposure to the company’s logo keeps it in the memory of potential customers. Having the logo in memory increases the chance that potential customers buy the company’s product instead of a competing product, if they need such a product. This appears to happen even if it is a seldom needed product – such as a car.

The UCLA (University of California, Los Angeles) conducted a study asking people to recall the Apple logo. As research results turned out the Apple logo was not as good memorable as one might think. 85 students took part in the study. The student’s age was between 18 and 35 years. 52 of the students are Apple users. Half of the people did not recognize the correct logo from a set of 8 distracting logos (exemplary see below). Interestingly the recognition rate was only marginally better for Apple users compared to other PC users.

However, if asked we seem to be confident about the accuracy of our memory. Overconfidence in the own memory accuracy was specifically higher if participants were asked before the memory task to rate their memory accuracy. When the participants were requested to do the memory task first, it made them more aware of the memory complexity and reduced the level of overconfidence in their own memory.

Source: Blake, A., Nazarian, M. & Castel, A. "Rapid communication - The Apple of the mind’s eye"

Source: Blake, A., Nazarian, M. & Castel, A. “Rapid communication – The Apple of the mind’s eye”

Beside a huge capacity for visual memory and long-term memory of visual data we seem to have poor memory for details. The researchers point out that the Apple logo is overrepresented in our daily live. In reaction to the overrepresentation we spend less attention to it, generalizing the logos form and avoiding attention to details. Naturally, if something appears frequently it is not necessary to memorize it in detail. So we memorize the logo as in the generalized form of an apple and add details as we think the apple Apple should look like. Maybe the memory is also influenced by the need for detail. I kept thinking of a similar logo that the apple Apple could potentially be confused with, but I cannot recall of something similar. Maybe people would have shown a better recognition for details if they were required to distinguish the Apple logo from something very similar.

If you want to try the test yourself:

Source: Memory of the Apple Logo – research conducted at the University of California, Los Angeles

Old Fire Alarm

February 1, 2015 Leave a comment

Lately I have been in a museum of a former research facility. In one of  the buildings I discovered an old fire alarm.

The fire alarm is mounted at the wall in form of a bright red disk (see photo below). To activate you have to swing the black handle around the disk. Spinning around it makes a bell-like sound with every turn. I’m not sure which time this system was developed. The research facility was used during WWII. So I guess the system must have been up to date at that time.

On public spaces they may used such kind of things to avoid many false alarms due to jokes. The system locks the hand of the person activating the alarm. After police or fire fighters arrive at the scene the person is freed by them.

2015-01-31 13.07.44

Early “graphic pen” in Sketchpad demo from 1963

October 14, 2014 Leave a comment

Already back then they had a, well kind of, graphic pan to paint on the display. Amazing.


History of ergnomics – time and motion studies Frank Gilbreth

September 30, 2014 Leave a comment

The today known field of Human Factors Engineering (or sometimes called Ergonomics) has a long history. It started out from efficiency to make tools more suitable for man so that they can work more efficient and productive. The studies used therefor are known as time-and-motion studies. Probably the earliest ones were conducted by Taylor. But Taylor’s was mainly focusing on work rates and worker motivation with the purpose to reduce process time.

The study conducted by Frank B. Gilbreth in 1911 is likely the first one which focused on the relationship between human, environment and tools to make the work more efficient by reducing motions. One of his famous time-and-motion studies concerned brick laying. Beside this he was also known for his systematic management style. For conduction of the motion studies he coded movements and actions of the worker related to work into 18 basic motions ( which he called “Therbligs” (Gilbreth spelled backwards). During the conducted motion study the therbligs are written down and analysed for optimisation like unnecessary movements.

In case of the bricklaying study he discovered that the bricklayer needs to bow for each brick and at cases a second time to get a bit water for the brick. Additional effort was it that not each brick could be used. If it was of minor quality the worker would need to throw it and bow again. The study resulted in the invention of a height adjustable scaffold on which the worker arranged a heap of bricks and the mortar. The scaffold could be quickly raised or lowered enabling the bricklayer to work at the most convenient positions and it further enables them to keep up with the height of the wall. By making the motions of handling and inspecting the bricks more efficient Gilbreth enabled bricklayers to increase the number of bricks that they could lay from 120 to 350 per man per hour.

Gilbreth enhanced the method developed by Taylor with what he called micro-motion analysis. Meaning the workers actions are recorded on a video with a chronometer running in the video. Afterwards follows the video analysis with a magnifying glass to discover every motion a worker makes and suggest improvements based on the length and sequence of the motions.

In the studies described were the first ones considering fatigue resulting from a job and the thought that the provision of an adequate work environment and regular breaks forms a more efficient process in the end.

However, the important component of cognition has still to wait until World War 2 until it is considered as important point and integrated into the field of human factors engineering. Cognition came into importance due to growing application of automation and automation specifically taking over the heavy physical work from the operator. What remains for the operator are mainly perception of information and decision-making tasks. Leading questions are e.g.: How much information can be absorbed? How many oxygen masks sizes are required to fit to all men? This was also the point where the field of human factors engineering melted with psychology. Because the questions could no longer be answered by engineers – it needed psychologists, physiologists and physicians.



On the website of the MIT there is a paper:

Frank B. Gilbreth’s book about bricklaying is free available online:

Hawthorne effect

The Hawthorne is also referred to as observer effect. It was first discovered by Roethlisberger and Dickson in 1939. They were hired by General Electric (GE) to conduct a series of studies in their plant in Chicago to examine how to improve work conditions for increased productivity. The concerned employees worked in an assembly-line.

Roethlisberger and Dickson started with a measurement in the baseline condition. They measured the employee’s productivity without changing the work conditions. Then they planned to make one change in the work environment and measure again to compare if and how the value for productivity changed. Firstly they increased lighting, and found that productivity improved. Then they increased lighting more, and again found that the productivity improved. Then they put the lighting setting to its original level, and, surprisingly, found that the productivity improved.

Cause for improvement was non of the changes they made to the work environment. Cause for the productivity increase was simply that the employees felt valued and respected if asked about their work and that the employees knew when a change occurred that it is made to find the best working conditions which made them work harder.

For their experiment it really helped them to use an ABA test condition. Meaning if they would have stopped their experiment after an AB test (usual work condition and condition with increased lighting) they may would have drawn the conclusion that increased lighting increases productivity. Setting it back to its original level and measuring again revealed the effect.

The effect was then named after GE’s plant: Hawthorne effect.

Their study is also described in their book “Management and worker” which you can find as google-book online.

However it is not uncriticised. Some researchers mention that the important thing is not the awareness of the observation itself that causes a change but a the subjects interpretation of the situation. If the experimental condition maps with the participants goals it could change the behaviour. Also influential can be effects to want to “please” the experimenter.

Miscited psychology concepts – Yerkes-Dodson law

As I wanted to write an article about the well-known workload scale I found this interesting story. Usability engineers know the and work with the workload scale. A task performance has its ideal level of workload. Is the workload higher than the ideal level the operator compensates this with application of more resources. If the workload rises more the operator can no longer compensate and gets overloaded, performance declines. In the other direction, if workload is below the ideal level the operator applies additional resources to keep attention to the task. If workload declines further, attention can no longer be kept to a sufficient level and performance declines. Some literature refers for origin of this process to the Yerkes-Dodson law. Let us have a look what they originally did in their study from 1908.

The study conducted by Yerkes and Dodson (original paper) evaluated the relation of stimulus strength and habit formation. Habit formation is seen as a type of learning. The experiment was conducted with a set of mice. The mice’s task was to distinguish between a black and a white box and learn to choose the white box. Selection of the black box resulted in an electrical shock. In the first experiment they presented the electrical stimulus in different strengths and assumed that the rate of failures (choice of the black box) is declining with stimulus strength. But the result revealed a rise of failures in the setting with the highest electrical stimulus. So they mused if this result could be related to the difficulty of the task (discrepancy between black and white box). For proof they conducted two other experiments varying the ease of distinguishability between black and  white box. Indeed the results showed that for the easiest condition failure rate declined with rising electrical stimulus strength.

Beside the miscitation in literature the study itself has its drawbacks: first the sample set of mice used was very small, the difference of black and white box was not measured with a photometer, the task was just comparable simple perceptual one and the analysis of results could be more accurate, they seem mixed over the experimental settings.

In respect of the study one would assume it to be cited in context of stimulus strength and habit formation, or maybe in context of a behavioural learning theory. But teh study has been cited in the literature as base for performance, workload and (physiological) arousal, concepts which where not part of the original experimental setting. A citation in relation to the workload scale ignores their second finding – if the task is easy, failure rate declines with increasing stimulus strength. Following question would be, what happens if the task is even easier? Are those effects applicable to humans with a wider range and flexible learning algorithms? Further it is not clear if a learning induced by a negative stimulus, as applied in the experimental setting, is comparable to higher workload which means also higher stimulus (rate / variance) but that is not negative… there are many questions rising in my head from this experiment. Well, somehow the misciting started…

A good review of the miscitations is this paper from Karl Halvor Teigen, link. Sometimes it is very hard to get hold of the original paper or its hard to read all that many literature of a topic and if something like this theory is so often cited in many psychology books it is a simply belief that it is true.  However, a critical eye is in advantage.