What are the key terms related to supervision and what do they mean?

GUIDANCE 

In this article, we break down key terms around visibility into simple bitesize definitions.

Visibility  

What a person can identify within a spatial area. 

Sensory field

The spatial perimeter of what can be sensed by a person.

Visual field

The spatial perimeter of what can be identified by a person.

Scanning 

A process of identifying and detecting persons in need of rescue

Identification

What a person can distinguish as an object or set of events within the sensory field. 

Artificial identification

What a machine can distinguish as an object or set of events from its data.  

Detection 

A process of interpreting the relationship between an object or set of events and a person(s) to determine the need to perform a rescue. 

Rescue

An intervening action, or set of actions, is taken by a person(s) to alleviate person(s) from danger.

Drowning

A process resulting in primary respiratory impairment from submersion or immersion in a liquid medium.

Perceptual blindness

A lifeguard cannot attend to all patrons simultaneously; therefore, some patrons must necessarily be unattended for some period of time. Inattention to stimuli can produce what has been characterized as perceptual blindnesses in the visual cognition literature (e.g., Rensink, 2000; 2008; Simons & Rensink, 2005)

What is intentional blindness?

Inattentional blindness (Mack & Rock, 1998) demonstrates that attending to one aspect of the scene—something that lifeguards must do constantly—can cause otherwise obvious, large, and significant events to go unnoticed (Wood and Simons, 2019).

Change blindness 

A related phenomenon is change blindness, which refers to the fact that observers can fail to notice (Rensink, O’Regan, & Clark, 1997) large and significant changes in scenes that they are scrutinizing despite being highly motivated to detect those changes. Observers sometimes even fixate on the change in the scene but still do not detect it (e.g., O’Regan, Deubel, Clark, & Rensink, 2000), suggesting that the problem concerns attention, not low-level visual processing.

Finally, and particularly relevant to a surveillance task like lifeguarding, change blindness can even occur in the context of live human interactions. Simons and Levin (1998) found that subjects failed to notice when a person with whom they were talking exchanged places with a different (previously hidden) person after disappearing for a moment behind a door.

The observer may miss signals because the changes (a new or changed stimulus) within the field of perception change slowly and go unnoticed (Rensink, O'Regan, & Clark, 1997).

Vigilance

Vigilance is one’s ability to focus attention and detect signals for an extended period of time under conditions where signals are intermittent, unpredictable, and infrequent (Lanagan-Leitzel, 2015).

Vigilance is defined as "the ability to detect unforeseeable and slightly suprathreshold signals" (Pieron, 1979).

The ability to notice and identify (weak) signals of risks in the environment. Vigilance is a highly desirable trait for lifeguards to possess. Watching in-water patrons constantly is physically and cognitively demanding. Dr Tom Griffiths (the inventor of the five-minute scanning strategy) states: “constant vigilant supervision is an oxymoron” (Griffiths, 2011).

Attention

"A selective mental orientation which includes an increase in efficiency within a certain activity mode, with the inhibition of concurrent activities" (Applied Anthropology, 2001). 

Turbidity

Light reflecting-off objects below the water are scattered by particles in the water, increasing the turbidity (lack of clarity or ‘cloudiness’) of the water. This is the functional equivalent of adding visual noise to the image of anything in the water (e.g., Baranov-Krylov, Shuvaev, & Astashchenko, 2011). Turbidity is often, although not always, low in pools. It is a bigger problem in open-water environments like lakes and the ocean.

Diffuse refraction

Second, light that passes through the air-water interface is refracted, disrupting the images of objects in the water. Refraction through multiple surface angles of turbulent water can render objects virtually invisible as the coherence of the image is completely disrupted (Griffiths, 2006).

Specular reflection

Third, light from an overhead source (e.g., the sun or fluorescent lights) can reflect off the surface of the water, obscuring the image of objects below the surface as the mirrored surface of a one-way mirror does.

Distraction

Distraction is defined as an “involuntary division of attention” (Sen, 1983, p.53). External distractions are diverting stimuli originating from an individual’s outside environment.

Internal noise

Internal noise is diverting stimuli from thoughts and emotions that can distract an individual from a task (Griffths and Griffths, 2013). Internal noise is far more difficult to recognize and more challenging to manage than an external distraction.

References

Applied Anthropology. (2001). Lifeguard vigilance. Bibliographic study.  

Baranov-Krylov, N., Shuvaev, V., and Astashchenko, A. (2011). Modification of evoked potentials by increasing visual search difficulty in humans. Rossiiskii fiziologicheskii zhurnal imeni I.M. sechenova. 96(4), 385-95.  

Griffiths, R. and Griffiths, T. (2013). Internal noise distractions in lifeguarding. International Journal of Aquatic Research and Education. 7(1), 56-71.  

Griffiths, T. (2012). The drowning D's. Presentation at the conference of the Association of Aquatic Professionals, Austin, TX (March).  

Mack, A. (2003). Inattentional Blindness. Current Directions In Psychological Science. 12(5), 180-184.  

Mack, A., & Rock, I. (1998). Inattentional blindness. (Cambridge, MA: MIT Press). 

Nelson, K., Laney, C., Fowler, N., Knowles, E., Davis, D., & Loftus, E. (2011). Change blindness can cause mistaken eyewitness identification. Legal And Criminological Psychology. 16(1), 62-74. 

O’Regan, J., Deubel, H., Clark, J., and Rensink, R. (2000). Picture changes during blinks. Looking without seeing and seeing without looking. Visual Cognition. 7, 191-211.  

Rensink, R. (2002). Change Detection. Annual Review Of Psychology. 53(1), 245-277.  

Rensink, R. (2008). On the applications of change blindness. Psychologia. 51, 100-106.  

Rensink, R., Kevin O’Regan, J., & Clark, J. (2000). On the Failure to Detect Changes in Scenes Across Brief Interruptions. Visual Cognition. 7(1-3), 127-145.  

Sammon, N., & Bogue, J. (2015). The Impact of Attention on Eyewitness Identification and Change Blindness. Journal Of European Psychology Students. 6(2), 95-103. 

Sen, A. (1983). Attention and distraction. (New York: Sterling Publishers).  

Simons, D. and Rensick, R. (2005). Change blindness. Past, present, and future. Trends in Cognitive Sciences. 9(1), 16-21.  

Simons, D., & Levin, D. (1998). Failure to detect changes to people during a real-world interaction. Psychonomic Bulletin & Review. 5(4), 644-649. 

Wood, K. and Simons, D. (2019). Processing without noticing in attentional blindness. A replication of Moore and Egeth (1997) and Mack and Rock (1998). Attention, Perception, and Psychophysics. 81, 1-11.  

Citation: Jacklin, D. 2022. What are the key terms related to supervision, and what do they mean? Water Incident Research Hub, 1 January.