---
{
  "schemaVersion": 1,
  "version": "1.2.0",
  "id": "P-002",
  "kind": "pattern",
  "title": "Progressive disclosure and memory load",
  "summary": "Disclose explanations and diagnostics without hiding information needed together.",
  "applicability": [
    "tabs",
    "drawers",
    "drilldowns",
    "multi-step flows"
  ],
  "related": [
    "P-001",
    "P-003"
  ],
  "rules": [
    "DR-003",
    "DR-006"
  ],
  "sources": [
    "E-DISCLOSURE",
    "E-RECALL",
    "E-DISCLOSURE-APG"
  ],
  "examples": [
    {
      "id": "disclosure-context",
      "quality": "good",
      "href": "../../examples/pricing.html?mode=compact&open=A",
      "task": "Investigate proposal A while retaining its action factors.",
      "consequence": "Expansion leaves the identity and summary in place."
    },
    {
      "id": "disclosure-navigation",
      "quality": "bad",
      "href": "../../examples/pricing.html?mode=sparse&open=A",
      "task": "Compare A with B while inspecting supporting factors.",
      "consequence": "The detail view replaces B and C, forcing revisitation."
    },
    {
      "id": "disclosure-primary-trends",
      "quality": "good",
      "href": "../../examples/pricing.html?mode=trends&task=trend",
      "task": "Compare demand histories before choosing review or hold.",
      "consequence": "Common-scale histories are visible together at desktop width; notes remain secondary."
    },
    {
      "id": "disclosure-hidden-trends",
      "quality": "bad",
      "href": "../../examples/pricing.html?mode=compact&task=trend",
      "task": "Compare the same demand histories before review or hold.",
      "consequence": "Collapsed histories hide information assumed essential for this task."
    }
  ]
}
---

# Progressive disclosure and memory load

## What to do and why

Separate information by its role in the task, not by whether it makes the page look busy:

| Role | Starting placement | Change the recommendation when… |
| --- | --- | --- |
| Factors needed together for comparison | Visible with alternatives and action context | The task becomes sequential and earlier factors no longer affect later choices |
| How a value was constructed | Labeled explanation or expansion beside the value | Method, freshness, or uncertainty routinely changes the decision; expose that part up front |
| Evidence for investigating an exception | In-place diagnostics or linked investigation | Exceptions are frequent, high consequence, or require comparison across many items |

This placement table is Viewrule's task-dependent synthesis of [disclosure](evidence/disclosure.md) and [recognition/recall](evidence/recall.md). Hiding infrequent controls can reduce distraction; hiding comparison operands creates a memory task. Neither “always show less” nor “always show everything” follows.

## Prefer, avoid, and exceptions

Prefer disclosure for long derivations and infrequent supporting work. Avoid separate tabs for operands of a routine comparison. Scrolling a long expansion can also remove context: retaining an item's header in the DOM is not the same as keeping it visible.

A detail page is appropriate for extended editing, a shareable investigation, or a multi-step audit. Carry the item identity and relevant summary forward; preserve filters and scroll position on return. If several expanded trends must be compared, use small multiples or a comparison workspace instead of an accordion that closes its neighbors.

## Examples

[Good: proposal A expanded](../../examples/pricing.html?mode=compact&open=A) reveals a labeled seven-day trend, its actual values, and diagnostic notes beneath unchanged routine factors. The uncertainty range remains in the collapsed row because the exercise assumes it matters before acting.

[Bad for comparing proposals: detail replaces the list](../../examples/pricing.html?mode=sparse&open=A). The underlying data is unchanged, but users cannot compare A and B without returning and opening another proposal. This may be good for a different task: editing A's complete contract alone.

### Change the task, keep the data

Use the task and presentation selectors to compare [visible demand histories](../../examples/pricing.html?mode=trends&task=trend) with [collapsed histories](../../examples/pricing.html?mode=compact&task=trend). For the trend task, history is essential alongside the price, range, and constraint. Shared dates and 0–200 scales put the histories together at desktop width; model notes remain expandable. On mobile the panels stack, so simultaneous comparison is lost and needs task-specific review.

Now switch back to the [routine task with compact rows](../../examples/pricing.html?mode=compact&task=routine): history is supporting evidence again. The data is identical; the information needed to act has changed. This is an explicit synthetic assumption, not evidence that operators never need trends.

[Rendered trend comparison](../../examples/images/guide-pricing-trends.png): 1200 CSS px wide, device scale 1.

A second good variant puts a short formula explanation in a disclosure while keeping its result, units, and material assumptions visible. A bad variant hides the units and period under “More”; identical numbers can then be mistaken for comparable quantities. These examples are design hypotheses, not measured cognitive-load results.

## Evidence and limits

[E-DISCLOSURE](evidence/disclosure.md) and [E-RECALL](evidence/recall.md) are practitioner guidance. [E-DISCLOSURE-APG](evidence/disclosure-apg.md) is W3C's informative implementation pattern, not experimental proof of reduced memory load. No universal memory-slot count or allowable number of tabs is asserted.

## Automated checks and judgment

Use `no-clip`, `context`, and declared visibility requirements under DR-003/DR-006. Check keyboard operation, focus, accessible names, and expanded state following the [disclosure pattern](evidence/disclosure-apg.md). The example uses a real button with `aria-expanded` and `aria-controls`. Automated geometry cannot decide whether an explanation is essential or whether users remember hidden values accurately. Inspect the expanded state and observe the complete task, including return navigation.