Before we dive into theories, let's consider some essential factors:

1. Context: Was the person sitting alone or in a crowded area? Were they standing or seated?

2. Environmental factors: Were there any distractions around them (e.g., loud noises, bright lights)?

3. Personality traits: Does the individual have a tendency to be absorbed in their phone or other activities?

Now, let's explore some potential explanations for this behavior:

1. Information overload: The person might be trying to manage an overwhelming amount of information, such as dealing with multiple messages, emails, or social media notifications.

2. Stress and anxiety relief: Repeatedly highlighting text or scrolling through contacts could be a coping mechanism to temporarily distract themselves from stressors, worries, or anxieties related to their daily life.

3. Memory aid: The individual might be using their phone as an external memory device, relying on highlighted texts or contact lists to recall important information or tasks they need to accomplish.

4. Social anxiety: They could be rehearsing conversations or responses to specific contacts, perhaps due to social anxiety or apprehension about interacting with others.

5. Attention deficit hyperactivity disorder (ADHD): In some cases, the repetitive behavior might be an unconscious coping mechanism for individuals with ADHD, as they may have difficulty sustaining attention on a single task.

To better understand this person's behavior, consider the following:

• Observe from a distance: If you're feeling curious, observe the individual from a comfortable distance to see if their behavior changes or remains consistent.

• Ask an open-ended question: If you have the opportunity, approach the person and ask an open-ended question like, "How's your day going so far?" This might help them share more about what's driving their behavior.

Keep in mind that these are just speculative explanations, and it's impossible to know for certain without further observation or direct interaction with the individual. Nonetheless, this thought experiment can foster empathy and understanding for others' behaviors, even those that may seem peculiar at first glance.