ABC Hints&Tips Overviews Reference Glossary Support
Contents : Overviews : Leeches

Difficult material: leeches

Material can be inherently difficult (e.g. numbers, sets, enumerations, etc.) or can be wrongly formulated. Mnemonic techniques and other tools can be used in tackling inherently difficult material (see: 20 rules of formulating knowledge in learning)

Important! A small proportion of difficult material in SuperMemo can consume a large proportion of your time

The term leech is used in SuperMemo to refer to ill-formulated items. An element is called a leech when it meets user-defined leech criteria such as number of memory lapses and current interval. These parameters can be defined when using View : Other : Leeches (Shift+F3). An element becomes a leech when the number of memory lapses passes a defined limit. However, an element is no longer considered a leech if this is remembered beyond a certain interval (independent of the number of lapses). 

Leech Hunting Options

Although View : Other : Leeches (Shift+F3) can be used to review, delete and reformulate leeches, the best approach to tackling most persistent leeches is to review them in detail one by one in the course of the learning process. In Tools : Options : Leeches, you can select the following leech management options:

Include semi-leeches checkbox can be used to tighten leech criteria. A semi-leech is an element that is one memory lapse away from becoming a leech. For example, if a leech is defined as an element with five or more lapses and an interval up to 60 days, an element with four lapses and 1000 day interval will be a semi-leech. If your collection is well-structured and you do not encounter many leeches, you can turn Include semi-leeches on to tighten leech supervision.

Leech Alert Wizard

If you choose Tools : Options : Leeches : Wizard, the following dialog will be displayed each time you encounter a leech during repetitions:

This is the function of individual controls:

Recommended leech strategy

If you use the wizard, make the following choices upon encountering a leech:

Defining and viewing leeches

The option View : Other : Leeches (Shift+F3) can be used to locate leeches in your collection. This option uses the element filter dialog box that can be used to find all element meeting a specific set of criteria such as the number of repetitions, number of memory lapses, length of the current interval, status (memorized, pending, or dismissed), type (item, topic or task), etc.

The purpose of locating leeches is to reedit most intractable items with a view to applying appropriate mnemonic techniques. Alternatively you can reset elements (e.g. to deal with them later), dismiss them (to use them only as reference, e.g. with Search : Find elements), or simply delete them. 

A new powerful tool against leeches is a possibility of exporting your leeches to a handheld device (see: Revolution in the pocket). Although, it may seem that pocket repetitions are usually done in conditions of lesser focus, working in the leech-only mode sets your brain onto an emergency alertness level. You approach repetitions differently if recall failure is expected. At time, this is enough to wrap your mind around harder material and gradually reduce the leech load.

To maximize the effectiveness of the learning process, you should learn to use View : Other : Leeches and periodically remove from your collection most intractable and badly structured material. 

filter.jpg (31675 bytes)

The following fields can be used to select the minimum and the maximum values that fall into the range defined for difficult elements:

If you do not want to use a given criterion, uncheck the check-box associated with a given field. If you do want to use it, check the check-box and specify appropriate minimum and maximum values.

By definition, all leeches are memorized items. This is why Type and Status fields of the element filter are disabled.

Once you click OK, all leeches meeting the specified criteria will be found and will be displayed in a browser. You can then use Learn in the leech browser (Ctrl+Alt+L) to make repetitions in the leech subset only.

Using Tools : Random test : Leeches you can run a random test on all leeches. However, you should remember that part of the leech problem is repetition that is too frequent (i.e. causing the spacing effect). This is why Auto-postpone and Auto-forget are so efficient. This is also why leeches are much less of a problem in heavily overloaded incremental reading

Leech parameters are stored between sessions in the file <supermemo folder>\<systems>\<collection name>\collection.ini in the section [Leech]


You can clear the Leech Alert with Esc
Semi-leeches cannot be auto-forgotten

You can clear the Leech Alert with Esc
(Jens Buurgaard Nielsen, Denmark, Thursday, August 09, 2001 9:53 PM)
Leech alert: Nice feature, but I hate that per default, the leech window becomes active. I don't want to move my mouse to another window to do the grading. I often use Space bar to activate the default button, and sometimes, it automatically moves to Postpone when I intended to grade myself Good
You can either disable leech alert entirely in Options or just clear it with Esc and continue the repetition cycle using standard keys

Semi-leeches cannot be auto-forgotten
(Mike Condron, USA)

Why can I not choose Include semi-leeches in leech manager for auto-postpone or auto-forget?
Semi-leeches are not leeches. They can be scheduled for repetition at very long intervals. Removing them from or reintroducing them to the learning process would be highly wasteful