A book by W. Schweiger, “Hypermedien im Internet: Nutzung und ausgewählte Effekte der Linkgestaltung” (Hypermedia: usage and selected effects of link figuration) contains interesting findings about intra-textual links (anchors right within the text, as opposed to extra-textual links in set-off link-lists).
- They reduce “decision quality” at “link selection and navigation” and reception quality,
- they increase “referential navigation” (distracting cross references as opposed to hierarchical links); and referential navigation, in turn, reduces orientation;
- combined with link annotation, however, they’re OK, especially because then they don’t seduce to thoughtless clicks.
In his tests, link annotation was differently implemented: with extratextual links, it was normal additional text, with intratextual links, however, it was quicktipps visible with mouse hovering. Furthermore, hierarchical links as opposed to referential links were IMO conceived in a very narrow sense, with special focus on navigational pages and areas.
In any case, intratextual links should
- be used sparingly, and if at all,
- be clearly marked (my favorite method is, for instance, to use green color for pure glossary-like links that do not contribute much to the subject being tackled, as MS help texts do and as the Encyclopaedia Britannica (before 2002) colored its index words).
- be annotated (since Netscape 7, finally the quicktip works with all relevant browsers).