Comments on Shimp's (1983) double dissociation between knowledge and tacit knowledge.

Eisler (1984) wrote a short theory piece. He looked at a 1983 pigeon study that claimed birds keep two kinds of knowledge: one they know they know, one they do not.

Instead of two systems, H said one fixed clock rule can explain the same data. The birds simply peck when the delay feels short enough.

No new birds were tested. The paper shows that the earlier double-dissociation pattern vanishes if you add a single time cutoff to the model.

In plain words, pigeons may just answer “was the wait shorter than X seconds?” instead of tapping separate memory banks.

THOMAS et al. (1963) first taught pigeons to match after delays. Their birds only passed when trainers started with zero-second delays and slowly stretched them. H’s rule fits that step-by-step climb.

Donahoe et al. (2000) later saw accuracy crash after 3–9 s while peck rates stayed high up to 27 s. That split also makes sense if birds use a strict time gate, not two knowledge boxes.

Brown et al. (1994) showed pigeons can form equivalence classes. The feat did not require separate explicit memory; a plain time rule could still sit underneath.

When you build delayed-matching or equivalence programs, test one simple timing rule before you add extra cognitive layers. Start with almost no delay, then lengthen it in one-second hops while watching for a sudden drop. That curve will tell you if the learner uses a fixed cutoff, saving you from inventing two separate teaching tracks.