Chapter 21: Skills, Reaction & Learning | Human Performance & Limitations

10. Reflexes, Reaction Time, Surprise & Startle

Reflexes, reaction time, surprise and startle — Figure 21.1 — Reflex vs reaction time, and the difference between surprise (unexpected) and startle (sudden and intense) — both steal precious seconds.

What this section covers Reflex types, what reaction time depends on, and the operational impact of the startle reflex on pilots.

Reflexes occur with little or no involvement of the central nervous system.

10.1 Reaction Time

There is a delay between detection, stimulus and muscle contraction called reaction time. Reaction time depends on the type of reflex action being used.

10.2 Three Types of Reflex Actions

Type	Description	Example
Unconditioned	Instinctive natural reflexes	Blinking
Conditioned	Reflexes that may be learned	Foot-on-rudder on swing
Trained	Reflexes that may be increased by repeated practice	Stall recovery inputs

10.3 Surprise and Startle

The startle reflex is a reflex-like event that blinks the eyes and causes a whole-body 'jerk' to occur (similar to that sometimes caused in sleep). The reflex has a relatively basic neural pathway from the sense organ. Many things can cause (or contribute to) a startle reflex:

Sudden noises
Unexpected tactile sensations
Abrupt shocking perceptions
The sensation of falling
An abrupt visual stimulus

There is little evidence that a startle reflex alone creates much of a sustained or lasting impact on cognitive functions, although there are some minor and short-lived physiological changes such as raised heart rate.

Key Value — Startle Recovery A skilled motor task will be momentarily disrupted by a startle reflex but return to normal within 5 to 10 seconds.

10.4 Effects on Pilots

The main effects of the pure startle reflex on pilots are:

Interruption of the on-going process.
Distraction of attention toward the stimulus.

These happen almost immediately and can be quickly dealt with if the cause is found to be non-threatening.

Hazard — Fear Potentiates Startle A perception of fear can cause a startle reflex to be potentiated (more pronounced) should it occur, and attention to become more focused. In a state of fear, very little is required to trigger a full 'fight or flight' response.

11. Quantitative Overload & Human Reliability

What this section covers When workload is acceptable, what overload looks like, error rates with practice, and the cumulative nature of errors.

Quantitative Overload — a very high workload can be interpreted as 'Stress'.

SOP — Acceptable Workload Workload may be said to be acceptable if it requires about 60 % of the crew resources, depends on the pilot's expertise and corresponds to the amount of resources available.

11.1 Most Common Symptoms of Overload

A sharp degradation of performance
Funneling of attention or focus
Regression
Mental "blocking"
Mood swings
Restlessness and trembling
Panic

11.2 Human Reliability

The rate of human error during simple and repetitive tasks might be expected to be 1 in 100, but after practice, a rate of 1 in 1,000 could be achieved.

Definition — Human Reliability The individual functioning in the manner in which he or she is supposed to function.

11.3 Error Generation

Errors tend to be cumulative. One slip rarely stays isolated — it sets up the next.

Worked Example — Human Error Rate A pilot performs 200 routine pre-flight checks per week.
• Before practice (1 in 100): expected errors ≈ 200 ÷ 100 = 2 errors / week.
• After practice (1 in 1,000): expected errors ≈ 200 ÷ 1,000 = 0.2 errors / week (i.e., about 1 every 5 weeks).
Practice yields a 10-fold reduction in error rate, but never reaches zero — hence the value of cross-checking and SOPs.

12. Short-Term & Long-Term Memory

What this section covers Duration and capacity of short-term memory, methods to expand it, the three subtypes of long-term memory and its capacity characteristics.

12.1 Short-Term Memory (Working Memory) — 10 to 20 Seconds

Short-term memory enables information to be retained for a short period of time. That information will be lost in 10 to 20 seconds unless it is actively rehearsed and deliberately placed in our long-term memory.

Auditory information is considered easier to retain than visual information as it is easier to rehearse sounds than data in a visual form.

12.2 Limitations of Short-Term Memory

The capacity of our short-term memory is limited. The maximum number of unrelated items which can be maintained in the short-term memory is about 7 ± 2. Once this limit is exceeded one or more of the items are likely to be lost or transposed.

12.3 Methods of Increasing Short-Term Memory

Method	Description
Chunking	Breaking items to be remembered into small pieces and remembering them one at a time.
Association	Used to remember spoken lists of items. A wild and bizarre association is imagined and attached to each item on the list.

Worked Example — Chunking an ATC Clearance Raw clearance string: "VTBL VTBS RWY01L SQK4732 ALT FL310 HDG270" — 7+ unrelated tokens, near STM limit.
Chunked: "VT-BL → VT-BS" (route), "RWY 01L" (departure), "4732" (squawk), "FL310" (level), "HDG 270" (heading) = 5 chunks — comfortably within 7 ± 2.

12.4 Long-Term Memory — Unlimited Time Period

It is believed that information is stored in the Long-Term Memory for an unlimited time period, although frequently there may be retrieval problems.

12.5 Three Subtypes of Long-Term Memory

Type	Definition	Example
Semantic Memory	Stores general knowledge of the world	Knowing that "QNH is altimeter setting"
Episodic Memory	Memory of events or 'episodes' in our life	Recalling your first solo flight
Procedural Memory	Skills are included within the make-up of the LTM	Executing a coordinated turn

Exam Tip — Memory Quick Facts • STM duration = 10–20 seconds, capacity = 7 ± 2 items.
• LTM capacity = unlimited, but retrieval problems may exist.
• Motor programmes live in LTM (Procedural), not STM.

13. Learning, Retention & Motivation

Figure 21.3 — The learning curve: rapid early gains, then a plateau; motivation and feedback drive it forward.

What this section covers Types of learning, methods to retain information, and the role and sources of motivation.

13.1 The Learning Process

Learning is an internal process which allows the mental acquisition and retention of data. Types include:

Insight

The data is intellectually and cognitively understood and is retained. Observational Learning / Imitation — data from an outside source is replicated. Experience — learning from our mistakes.

Skill Learning

Involves motivation, attention, observation, much practice and corrective feedback.

13.2 Retention of Information

Retention can be increased by:

Mnemonics — the practice of improving or helping the memory, or the systems used to achieve this.
Memory Training

13.3 Motivation

Motivation is the combination of a person's desire and energy directed at achieving a goal. It is the cause of action.

Type	Examples
Intrinsic	Satisfaction and feelings of achievement
Extrinsic	Rewards, punishment, and goal obtainment

Not all people are motivated by the same thing and over time their motivations might change.

SOP — Motivation and Performance The learning process is vastly improved with motivation, and high performance is rarely achieved without it.

14. Experience, Response, Cognition & Hallucination

What this section covers How experience shapes us, response characteristics with age, error of commission, response times, cognition in flight, and hallucinations.

14.1 Experience

We all have the ability to learn from our experiences and mistakes, and from those of others.

14.2 Response

Any response will cause a detectable change which, in turn, will be noted by the senses. The feedback may alter the action being taken.

Auditory stimuli (noises) are more likely to attract attention than visual stimuli, but they are also more likely to be responded to in error.
An increase in age between 20 and 60 years tends to lead to slower but more accurate responses.

14.3 Response Error (Error of Commission)

If an unexpected stimulus occurs, we will be more likely, under pressure, to make an error of commission.

14.4 Response Times

Response to reaction time is the interval between the onset of a given signal and the production of a response to that signal.

14.5 Cognition in Aviation

Cognition = the mental faculty or process of acquiring knowledge by the use of reasoning, intuition or perception. In aviation, flight puts the pilot into an environment which can distort sense organs, and the changed perspective which is experienced in flight can result in information being presented which is outside the individual's expectations.

14.6 Hallucination

A hallucination is actually a false perception characterised by a distortion of real sensory stimuli. (Not a fabrication of stimuli — the stimuli are real, but their perception is distorted.)

14.7 Workload and Limitations

Too high or too low a workload can result in degraded performance. Several types of situations may cause mental overload.

Exam Tip — Age and Response Between 20 and 60 years → responses become slower but more accurate. Experience compensates for slower reflexes.