​Johnson, J. (2014). Designing with the mind in mind: simple guide to understanding user interface design guidelines (2nd ed.). Boston: Elsevier.

This Chapter covers the design principles developed in the early 20th century by a group of German psychologists call the Gestalt principles. The core theory of the principles is that the part of our brain that is responsible for sight, also orders the world as shapes rather than disconnected lines and edges. The basic theory of this has been maintained in modern neurophysiology (Johnson, 2014, p. 13).  Johnson describes the most important of Gestalt principles for UI design are the following; proximity; similarity; continuity; closure; symmetry; figure/ground; and common fate. Proximity is the relative distance between shapes which determines how we see them and organise them into groups, in his example Johnson uses the image bellow to where in we see the stars in rows or columns based on their proximity horizontally or vertically respectively. 

​Similarity is when objects appear to be visually similar or identical they seem to be grouped together, this can work to the detriment of proximity if one wishes to group to distinct objects multiple times, as is seen in Johnson’s example of Elsevier.com where the text is more grouped with the other text than the fields and vice versa. However proximity can also be used to prevent the grouping as seen in the Mac OS Print menu where the text and drop-down menus are visually linked to each other rather than there visual counterparts due to the separation between them.  

Continuity is how our brains are able to infer and deduct how an obscured object continues despite being unable to see it as a whole, this is used rather often in visual illusions.In Johnson's example we connect the red lines together and same with the blue lines and surmise that they have been blocked by the white circle rather than all four having emerged separately from its edge. 

​Closure is closely tied with continuity as our brains try to close broken shapes so that they may be seen as a whole. Symmetry we try to break down complex shapes into combinations of multiple simple shapes. Figure/Ground is the visual break between the foreground and the background, uniquely this principle can also be determined visual as well as by the intent of the viewer. Similar to when in a conversation other noise in the environment can be called background noise, the foreground is determined by what information is more valuable to the viewer.  Common Fate concerns moving objects where in objects moving in a similar way become visually linked.

Computer History Museum. (N/A). Timeline of Computer History. Retrieved October 22, 2019, from Computer History Museum: https://www.computerhistory.org/timeline/computers/
Levy, S. (2018, MAy 29). Graphical user interface. Retrieved October 24, 2019, from Encyclopædia Britannica: https://www.britannica.com/technology/graphical-user-interface
Pottenger, W. M., Hemmendinger, D., & Others. (2019, January 30). Computer. Retrieved October 22, 2019, from Encyclopædia Britannica: https://www.britannica.com/technology/computer/History-of-computing
Tan, D. S. (2014, June 12). Human-machine interface. Retrieved October 24, 2019, from Encyclopædia Britannica: https://www.britannica.com/technology/human-machine-interface
Zimmermann, K. A. (2017, September 7). History of Computers: A Brief Timeline. Retrieved October 22, 2019, from Live Science: https://www.livescience.com/20718-computer-history.html
The article on computer history by Zimmermann seems to be a rather Americentric perspective on computer history though her work does help to high light significant mile stones in the history of computing that I a searching for.

• 1964: Douglas Engelbart shows a prototype of the modern computer, with a mouse and a graphical user interface (GUI). This marks the evolution of the computer from a specialized machine for scientists and mathematicians to technology that is more accessible to the general public.
• 1981: The first IBM personal computer, code-named "Acorn," is introduced. It uses Microsoft's MS-DOS operating system. It has an Intel chip, two floppy disks and an optional color monitor. Sears & Roebuck and Computerland sell the machines, marking the first time a computer is available through outside distributors. It also popularizes the term PC.
• 1985: Microsoft announces Windows, according to Encyclopedia Britannica. This was the company's response to Apple's GUI. Commodore unveils the Amiga 1000, which features advanced audio and video capabilities.

(Zimmermann, 2017)
 
The Encyclopedia Britanica has articles on the Human-Machine interface, which is another term for user interface. It is the means by which humans and computers communicate with each other with hardware (mouse, keyboard ect.) and software (operating systems)  

• Evolution Of The Human-Machine Interface -The evolution of the human-machine interface can be divided into several historical phases, marked by the dominant interface of the time. In the 1950s the prevalent model was batch processing, in which users specified all details of a task (typically on punch cards), executed them (by feeding the cards to the machine), and received results an hour or more later, when the processing was fully completed. Batch processing was tedious and error-prone. The batch interface was followed by developments in command-line interfaces, which allowed users to interactively issue commands that the system immediately executed and produced results for. Command-line interfaces, although an improvement, did not take full advantage of human perceptual, cognitive, and learning abilities. Those abilities were leveraged with the development of graphical user interfaces (GUIs) in the mid-1960s and early ’70s. In modern GUIs, users engage in rich communication with the computer by using various input devices.

The section of the article provides a good reference point for contextualizing the history of the user interfaces alongside the history of modern computers. 

Katherine E. Olson, M. A. (2011). Diffusion of Technology: Frequency of Use for Younger and Older Adults. PubMed Central(36), 123-145. doi:10.1007/s12126-010-9077-9

​“General Computer Use: We first asked the general question, “Have you had experience with computers?” (yes or no). Not surprisingly, there was a significant difference between younger and older adults; X2 (1, N=679) = 64.25, p < .05, whereby 99 percent of the younger adults responded “yes” compared to 80 percent of the older adults.”

 This study asked for the participants to self-report the functions of a computer along with the peripherals and software that they use. This in contrast to the last study appears to be more robust and helpful in ascertaining information on this subject. The researchers concluded that the older subjects were not adverse to technology but instead slower to adopt the emerging technology that the younger subjects, in the exception of healthcare technologies where the older audience had more frequent use. (Katherine E. Olson, 2011)

Below are the graphs found in the study. 

Volkom, M. V., Stapley, J. C., & Amaturo, V. (2014). Revisiting the Digital Divide: Generational Differences in Technology Use in Everyday Life. North American Journal of Psychology, 557-574.

This study examines the sex and generational differences in the use of technology and the perceptions of technology of the 262 participants with an age range of 18 to 92.  

​“For example, fifty-five percent of adults access the Internet via their mobile phone and adults under 50 years old are just as likely to use mobile Internet access as teenagers (Madden, Lenhart, Duggan, Cortesi, & Gasser, 2013). Recent reports of the percentage of teens who own a tablet (25%) are almost the same for adults between 18-50 years old (23%). However, in general, older adults tend to express less interest in technology (e.g., computers), and use less variety of technology than younger adults, which affects how prevalent technology is for older users (Czaja et al., 2006). Younger users (18-28) of technology usually have more experience with various types of technology and functions of technology (Olson, O’Brien, Rogers, & Charness, 2011), such as experience with different computer parts and computer functions”

​Upon further reading this study appears to be somewhat flawed in that the vast majority of it only sites other papers. Also, the age ranges used are very broad. Thought the referenced studies in this document appear to be more insightful. Also, there is no research primarily undertaken by this study of the age divide in the use of technology instead it relies on secondary sources. 

--Johnson begins this chapter by outlining the biasing factors of The Past (our experience); The Present (the current context); and The Future (our goals).  He then proposes the Idea of perceptual priming where in we can be influenced giving the example of 

This context in the present primes the audience’s mind to see building shapes, however, if the image was primed as a billboard that reads “Life” then the white areas begin to clearly register as text. A similar scenario can occur with shapes known as pareidolia, since our brains have evolved to be able to recognise human faces, we sometimes see them in places where none exist, for instance in 1976 the Viking 1, prior to landing on Mars took Images from orbit. One of which (shown below on the left) became known as the as the “Face on Mars”, however in 2001 NASA concluded the primary mission of Mars Global Surveyor (MGS) project which captured a higher resolution image of the area, showing the face to have been an optical illusion brought on by circumstantial lighting.

--​We are also influenced by familiar patterns; our past experience of these patterns influences our behaviours when we are experiencing a similar scenario. An example provided by Johnson is the following image, this shows an example within UI design were user’s past experience makes them take for granted the location of the “Next” button. 

--​Johnson describes habitation as another influence on our perceptions where in recurring exposure to the same perceptions reduces our sensitivity to them. He states that this occurs on a neural level where our minds begin to ignore repetitious elements of the world.
“We experience habituation in computer usage when the same error messages or “Are you sure?” confirmation messages appear again and again. People initially notice them and perhaps respond, but eventually click them closed reflexively without bothering to read them.” (Johnson, 2014, p. 5)
By this fact using reedition can be beneficial to the user in addition to being disadvantageous in other situations. The reflexive knowledge of the UI assists in navigation of consistent menu elements, however notifications placed in the same location and used too frequently would cease to be notifying. 

--Attentional blink is a phenomenon referenced by Johnson where recognition of a stimuli with multiple stimuli quickly succeeding each other impedes our ability to recognise the next set of stimuli.  

A good example may be the Marvel logo stings that play in the Disney Marvel Movies. 

--In explaining how perception is bias, Johnson discusses how it is influenced by current context. To example this he uses optical illusions to demonstrate how what we understand of what we see is predicated on its surroundings especially when the image is obscured in some manner, for this he uses the Muller-Lyer illusion (figure 1.6) when two lines of equal length appear to be different lengths due to the fins or arrows at the end. 

--However, this example only demonstrated bias from a visual context, however perceptual bias can occur across the senses with each sense potential biasing the others. Johnson quotes the McGurk Effect wherein a video of someone saying “bah, bah, bah” then “dah, dah, dah”, then “vah, vah, vah” the viewer will hear the syllable indicated by the speaker’s lip movements rather than the audio. This is similar how in ventriloquism we are tricked that the dummy is speaking. (Johnson, 2014). Furthermore, we have our perception biased by our goals biased by our goals. The goals specified by Johnson are 

Johnson is saying that users will seek solely for the object of their query and become perceptually blind to any unrelated result.  He states that this behaviour is influenced by age as adults become more goal oriented where as children are less goal orientated than adults making them more likely to observe more but be more easily distracted. (Johnson, 2014)
In order to avoid perception bias, he proposes three solutions.

1. Avoid Ambiguity, ensure that all users can interpret the site the same way, and where it unavoidable rely upon conventional design to assist the user.
2. Be Consistent, ensure that recurring elements, such as controls and headers, are in the same location on each page that occur on.
3. Understand the Goals, the designer must consider why and what the user is using the website and what they need to operate and navigate the site.