ACM Interactions

Picture this: Sitting in his kitchen, young Tim chuckles at the recent misfortune of neighbors who fell prey to burglars. At the same time, he’s enthusiastically experimenting with a banking app on his fresh-off-the-assembly-line computer, a machine devoid of even the most fundamental antivirus protection. This scenario is a striking illustration of the privacy paradox. We voice anxiety about our data’s usage, often lambasting corporations with lax privacy protocols, only to defy our apprehensions by not embracing measures to safeguard ourselves. Let’s dissect this intriguingly paradoxical user behavior from the lens of perceptual psychology, illuminating the circumstances under which we sense privacy or publicity, distinguishing these states, and suggesting ways to aid individuals like Tim.

Perception in Private and Public Surroundings
Envision an intensely private moment: reclining on your sofa, shaking off the weariness of work. Now, contrast this with a public spectacle: accepting accolades onstage for special achievements, with a massive audience bearing witness. How do these scenarios make you feel, and what sets them apart? To shed light on this question, we will go deep into our bodies’ states and processes. A key environmental distinction arises when we feel private—the high likelihood of being cocooned in a familiar setting, surrounded by well-known objects and people, which lets us unwind. New experiences, however, kick-start our alertness; they ignite our curiosity and grab our attention. 

Fundamental cognitive processes in any living organism include sensation and perception. Familiar environments envelop us with recognizable items, triggering well-known sensations, be they sounds, scents, tactile sensations, or visuals. Therefore, private settings pose fewer challenges to the perceptual system about object identification and sensory memory. This reduction in demand allows the system to function at a lower sensitivity level, freeing up capacity for other operations.

This perceptual mode is accompanied by physiological processes. Broadly speaking, in relaxed, private settings, the parasympathetic neural activation (“rest and digest” mode) is dominant, whereas the sympathetic activation (“fight or flight” mode) is dominant in unfamiliar public settings. There are some remarkable perceptual effects caused by this: Sympathetic activation leads to larger pupils, resulting in more light input, in a slightly extended visual field, and in reduced visual acuity, especially outside of the eyes’ focus—that is, in periphery and in depth [1]. We therefore can assume that in public relative to private settings, we perceive with less spatial accuracy from a larger visual field. 

Attention in Private and Public Surroundings
Perception is accompanied by an adaptation of attentional processes. All attentional functions respond to situational affordances. We can differentiate between alertness and selective attention. Alertness is the increase and maintenance of response readiness. It can be supposed to complement the general arousal level of an organism. Thus, alertness will be high in public settings, while it can be reduced when the organism is surrounded by familiar objects. The notion of a broader visual field, although with lower spatial resolution, can be plausibly assumed to support alerting functions in public settings.

Regarding selective attention, new salient stimuli are known to capture attention. This improves visual search performance. In private surroundings, distracting objects can be quickly identified and thus be effectively suppressed. This can lead to a phenomenon known as inattentional blindness: In familiar settings, it frequently happens that we miss even uncommon, unexpected objects. The visual system is also capable of suppressing distracters based on their spatial location [2], improving efficiency in familiar environments. The familiarity of surrounding objects eases not only the selection of task-relevant objects but also the suppression of distracting objects. Inhibition again saves capacity for other processes [3]. In unfamiliar public settings, however, stimuli must be processed until they are identified as harmless, and suppression of task-irrelevant stimuli is thus more difficult.

The dichotomy between private and public settings even manifests in our posture and movements. Onstage, we present our bodies to a large audience, making exaggerated, sweeping gestures. Conversely, in private, our muscles can relax, leading to smaller, more restrained movements. This difference extends to eye movements and gaze, which in turn influence perception.

Level of Control in Private and Public Surroundings
Taken together, private settings lessen the need to attend to external stimuli; you can unwind and rely on the consistency of the surroundings. Also, perceiving things provides already familiar information. All these processes diminish the need for cognitive control, allowing processing to occur more subconsciously. Consequently, executing learned skills, routines, and habits becomes more probable. Public behavior, however, is marked by unfamiliar surroundings. The influx of novel objects or people prompts a slew of questions: Is that unfamiliar face a threat? What does that unexpected sound imply? This cognitive appraisal demands effortful attention, sapping mental resources, making us more cautious in and conscious of our actions [3].

This thinking aligns with Daniel Kahneman’s [4] idea that human behavior is regulated either by quick, instinctive, and emotional processing (as in private settings) or by slower, more deliberative, and logical processing (common in public settings). Crucially, it’s nearly impossible to engage both methods simultaneously. Therefore, in a situation prompting emotional automated processing with only weak conscious monitoring, we’re hardly capable of producing analytical thinking with logical deductions. This means that if users engage with their personal devices at home, their behavior is dominated by automated, nonconscious routines.

Counteracting Perceived Privacy by Simulating a Public Audience
So, how can we assist users in selecting an appropriate level of control? Novelty in environmental stimuli can be an indicator. How we process these cues shapes how we perceive and interact with our surroundings, be they private or public. The cues could be signals or symbols [5]. Signals are automatic cues operating beneath conscious thought, like the familiar ticktock of a clock or the distinctive feel of your sofa, directing our arousal and attention needs. Conversely, symbols, such as GDPR text, demand conscious, detailed analysis, and interpretation, thus requiring higher cognitive capacity.

Discerning the psychological differences between private and public settings equips us with a potent tool to mold privacy behavior and promote prudent disclosure. As we’ve noted, using personal devices in private settings often sparks cues associated with private behavior, possibly leading to a false sense of security. Thus, introducing cues that simulate public scenarios could stimulate public consciousness, reminding users to be more circumspect with their disclosures. These could be visuals, sounds, smells, or other elements that evoke the public nature of their online interactions. One subtle method to induce a feeling of publicity could be the “watching eyes effect”: The presence of a pair of eyes can influence disclosure behavior and can be fine-tuned by varying emotional expression, sex, and age of the eyes [6]. Ideally, this should be achieved by incorporating design elements that subtly disrupt users’ familiar routines, prompting a cognitive response akin to being in a public setting.

Toward a Privacy-Sensitive Future
To conclude, traversing the maze of privacy behavior is an intricate task, yet understanding the interplay of environmental cues, perception, attention, and behavior control can illuminate our path forward. Preserving privacy might be bolstered by subtly simulating publicity within digital environments, evoking vigilance, and awareness akin to our natural responses in public settings. By doing so, we can harness our inherent cognitive and physiological processes.

Endnotes
1. Eberhardt, L.V., Strauch, C., Hartmann, T.S., and Huckauf, A. Increasing pupil size is associated with improved detection performance in the periphery. Attention, Perception, & Psychophysics 84, 1 (2022),138–149; https://doi.org/10.3758/s13414...

2. Sauter, M., Liesefeld, H.R., Zehetleitner, M., and Müller, H.J. Region-based shielding of visual search from salient distractors: Target detection is impaired with same- but not different-dimension distractors. Attention, Perception, & Psychophysics 80, 3 (2018), 622–642; https://link.springer.com/arti... 

3. Posner, M.I. and Petersen, S.E. The attention system of the human brain. Annual Review of Neuroscience 13, 1 (1990), 25–42.

4. Kahneman, D. Thinking, Fast and Slow. Farrar, Straus, and Giroux, 2011.

5. Rasmussen, J. Skills, rules, and knowledge; signals, signs, and symbols, and other distinctions in human performance models. IEEE Transactions on Systems, Man, and Cybernetics SMC-13, 3 (1983), 257–266.

6. Lau, W.K., Sauter, M., Bulut, C., Eberhardt, L.V., and Huckauf, A. Revisiting the watching eyes effect: How emotional expressions, sex, and age of watching eyes influence the extent one would make stereotypical statements. Preprint, 2023; https://doi.org/10.21203/rs.3....

Wee Kiat Lau

Lisa Valentina Eberhardt

Marian Sauter

Anke Huckauf