ABC Hints&Tips Overviews Reference Glossary Support
Contents : Overviews : Rescheduling
Postpone

Learn : Postpone can be used to move outstanding material review to a later time whenever you cannot cope with your daily load of repetitions. This option is particularly useful in heavily overloaded incremental reading. To fully understand the importance of Postpone, you need to master the concept of incremental reading first.

Why is Postpone important?

Before the advent of incremental reading in SuperMemo, you had two extreme alternatives:

  1. traditional learning with high volume of the learning material and dismal retention. This learning can be called High In - High Out (HIHO) as high volumes of knowledge processed on the input are accompanied by equally high volumes of knowledge on the "output" (i.e. lost out to forgetting)
  2. SuperMemo with a small volume of strategic material remembered for years with a predetermined level of knowledge retention (LILO - Low knowledge input with low forgetting outflow)

Neither alternative provides a complete solution to the problem of forgetting. The balance between the two alternatives was left to the student. The optimum strategy was to use traditional learning to sift the strategic material, and then to memorize mission-critical material with SuperMemo. 

The confinement of SuperMemo to strategic high-retention material was a powerful inhibitory force against SuperMemo's universal adoption:

  1. The process of selecting the strategic knowledge was not automated
  2. The student had to type in most of the learned knowledge to the program
  3. The student had to master knowledge structuring skills to make the memorized knowledge truly applicable
  4. Passive review was discounted as ineffective and was not used as a knowledge prioritization tool
  5. Retention was programmable solely via the forgetting index (within 3-20% forgetting rate)
  6. Accumulation of outstanding material after a short break was listed as the number one cause of users dropping SuperMemo for good

Incremental reading bridges the worlds of traditional learning and that of SuperMemo by providing a fluent transition between all priority levels starting from quick review, to repeated passive review, to active review, and to active recall at all level of the forgetting index down to 3% (i.e. nearly 99% recall rate). Incremental reading also includes an anti-overload option: Postpone that blurs the concept of the must-do outstanding material that had levied a heavy toll on the ranks of SuperMemo users.

Before SuperMemo 2002, incremental reading did not automate the process of "prioritizing by overflow". In other words, high volumes of learning would force the student to manually reschedule learning in branches or subsets of lower priority. Manual rescheduling of the material was necessary to protect core knowledge from a dramatic drop in retention. Substantially reduced retention slows down the learning process not only via the forgetting index vs. acquisition rate relationship, but also through unraveling of the incremental reading process where the new knowledge is built on a shaky foundation of what has been learned earlier. In addition, the flow of thought in incrementally read articles becomes disrupted if the core knowledge retention is not protected.

SuperMemo 2002 introduced Postpone to make it possible to reschedule lower priority material with a keystroke. The student could now painstakingly work out priorities for individual subsets or branches of knowledge and then apply these easily on a daily basis.

SuperMemo 2006 dramatically simplifies the process of handling material overflow by introducing the auto-postpone option (Learn : Postpone : Auto-postpone). With auto-postpone, you only need to define the priority of your elements. You can safely leave all postpone parameters in their default settings as these are now primarily used only to define the degree of postpone, which only defines the size of the pool of the low priority material used in interspersing the repetition queue without affecting the high priority material. In simple terms, you do not need to understand Postpone to use it effectively in incremental reading. Just leave Learn : Postpone : Auto-postpone checked. You can re-visit the subject if auto-postpone does not sufficiently reduce the workload in your collection.

Warning! Each time you use Postpone you depart from your chosen level of knowledge retention! Never use Postpone on your most important learning material! To see the effects of rescheduling on the forgetting index see: Theoretical aspects of learning (forgetting index recovery figure)

Postpone dialog

The Postpone dialog box presented below includes three tabs: Scope, Parameters, and Adjust. The Scope tab settings are mostly done automatically for you depending on the context in which you use Postpone. The Parameters tab makes it possible to define the degree to which items and/or topics are postponed in the selected subset, and which items and/or topics are exempt from rescheduling. Once you define Parameters you can save the new setting with Scope : Save. Later you can restore the setting by using Settings name box.

Parameters tab

You need to understand the Parameters tab if you want to customize the degree of delay in rescheduling.

Delay factor determines how much elements should be delayed. For example, if you choose the delay of 1.1 (10%) on an element with the interval of 100 days, it will be delayed by ten days, i.e. rescheduled to the interval of 110 days. Postpone will always increase intervals by no less than one day from the present day. This way, all items on which Postpone is executed fall out of the outstanding subset. 

Maximum interval puts a ceiling on the length of the delay interval. For example, if you choose the delay of 1.1 on an element with the interval of 200 days, and the maximum interval is 5 days, the element will be delayed only by 5 days (instead of the 20 days produced by multiplying the original interval by the delay factor).

Minimum interval puts a floor on the length of the delay interval. For example, if you set it to 3, all delayed elements will be delayed by no less than 3 days.

Skip conditions determine which elements will be exempt from delay.

Adjust tab

The Adjust tab can be used for fine tuning delays on subsets with a complex priority structure of individual branches of knowledge. Sub-branch postpones determines how the rescheduling procedure interprets branches included in the subset that have their own postpone setting defined. Here are the possible options:

Advanced settings on the Adjust tab include: Include elements that are not outstanding (switching between Postpone and Dilute), Modify item delay in proportion to the forgetting index (for delaying items in proportion to the forgetting index) and Modify topic delay in proportion to A-Factor (for delaying topics in proportion to their A-Factor).

Simulate, Postpone and Dilute

Once you define the settings on the Parameters tab and, optionally, fine tune them on the Adjust tab, save them with Save on the Scope tab. You can now test the postpone procedure by clicking Simulate. If you are not satisfied with the results, redefine Parameters. Once you are happy with the result of the simulation, Save the settings and choose Postpone

The option Dilute should only be used in rare circumstances. It is analogous to Postpone but it also delays elements that are not outstanding. There are two main reasons for using Dilute:

Using Postpone in various contexts

Examples

If your daily load of items and topics keeps increasing, you can dilute the learning process with selective postpones from time to time. For example you can opt to delay repetitions in subsets such as:

Here are some typical ways in which you will execute Postpone:

Postpone or Mercy?

Postpone should drastically reduce the role of Mercy in SuperMemo. However, you may still need Mercy in the following circumstances:

  1. Randomizing repetitions (Mercy : Criteria : Randomize)
  2. Rescheduling the outstanding material after a longer break (with chosen Mercy : Criteria)
  3. Advancing future repetitions to an earlier date (e.g. before a vacation)

See also: