Subject Line Psychologist

Execution Steps

Step 1 - Define the open reason Decide whether the subject line should trigger curiosity, identity, urgency, reassurance, or specificity. Research basis: different attention states respond to different cues (attentional capture research; Song et al., 2024).

Step 2 - Build the smallest useful gap Create a gap the reader can plausibly close by opening the message. Research basis: curiosity works when the answer is accessible and relevant (curiosity research; Green & Brock, 2000).

Step 3 - Add self-reference when useful Use the reader's own problem, role, or aspiration if it feels natural. Research basis: self-relevance increases attention and processing (Moyer-Gusé et al., 2022; Ooms et al., 2019).

Step 4 - Check sender trust interaction Make sure the subject line and sender name work together. Research basis: open behavior depends on trust, not just wording (Rowley et al., 2015).

Step 5 - Sanity-check for promise continuity Confirm the email body resolves the promise cleanly. Research basis: overpromising harms trust and future opens (Nagy et al., 2022).

DECISION MATRIX

Variable: sequence position

• If first email -> use clarity and relevance.
• If mid-sequence -> use curiosity or proof.
• If final ask -> use specificity and decision clarity.

Variable: audience temperature

• If cold -> use low-pressure relevance.
• If warm -> use curiosity plus outcome.
• If hot -> use directness and immediacy.

Variable: device context

• If mobile-heavy -> keep the subject line short and front-load the mechanism.
• If desktop-heavy -> you can support a slightly longer thought.
• If mixed -> optimize for the shortest readable version.

FAILURE MODES - DO NOT DO THESE

Failure Mode 1

• Agents typically: write bait-y subject lines.
• Why it fails psychologically: the open may happen once, but trust drops over time.
• Instead: make the gap real and satisfied by the email.

Failure Mode 2

• Agents typically: personalize in a creepy way.
• Why it fails psychologically: overly specific personalization can trigger discomfort.
• Instead: keep personalization useful and unsurprising.

Failure Mode 3

• Agents typically: ignore preview truncation.
• Why it fails psychologically: the mechanism disappears before the open.
• Instead: front-load the useful cue.

ETHICAL GUARDRAILS

This skill must:

• Be truthful.
• Avoid deceptive urgency.
• Preserve reader consent and trust.

The line between persuasion and manipulation is using the subject line to earn attention honestly versus manufacturing false intrigue or threat to force an open. Never cross it.

SKILL CHAINING

Before invoking this skill, the agent should have completed:

• @sequence-psychologist
• @customer-psychographic-profiler
• @awareness-stage-mapper

This skill's output feeds into:

• @sequence-psychologist
• @copywriting-psychologist

OUTPUT QUALITY CHECK

Before finalizing output, the agent asks:

• Does the subject line create a real open trigger?
• Is it matched to sequence position?
• Does it fit the sender trust context?
• Is it short enough for the device context?
• Does the email body satisfy the promise?

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.