IDA functions by means of flexible, serial but overlapping cycles of activity that we refer to as . The overarching hypothesis, the , emerges from the IDA model. This hypothesis claims that each taking approximately 100-200 milliseconds, but due to overlapping, potentially occurring at a rate of more than five to ten cycles per second. Citing evidence from Thompson et al. (1996) and from Skarda and Freeman (1987), Cotterill speaks of “… the time usually envisioned for an elementary cognitive event … about 200 ms” (2003). From our cognitive cycle hypothesis, it might seem reasonable to call one such cycle an elementary cognitive event. Freeman (1999) suggests that conscious events succeed one another at a “frame rate” of 6 Hz to 10 Hz as would be expected from our cognitive cycle hypothesis (see also Freeman 2003b). The rate of such cycles coincides roughly with that of other, perhaps related, biological cycles such as (Steinman, Kowler and Collewijn 1990), , and (Seashore 1967). Could these hypothesized cycles be related to hippocampal theta waves (at 6-9 Hz) with gamma activity superimposed on them (VanRullen and Koch 2003)?
Such memory situations have been studied experimentally, giving rise to the dual-process hypothesis of two distinct memory processes being involved (Mandler 1980, Jacoby and Dallas 1981, Rugg and Yonelinas 2003). Subjects are often asked whether they recognize a target word as having been recently seen. A reliability judgment often accompanies the answer to measure the “continuum” of familiarity. A positive response is followed by a query as to recollection of the context in which the word was seen.
In the recognition memory literature dual-process models have been put forward proposing that two distinct memory processes, referred to as and , support recognition (Mandler 1980, Jacoby and Dallas 1981). Familiarity allows one to recognize the butcher in the subway as someone who is known, but not to recollect the context of the butcher shop. In the IDA model, PM alone provides the mechanism for such a familiarity judgment, while both PM and DM are typically required for recollection. Recent brain imaging results from cognitive neuroscience support a dual-process model (Rugg and Yonelinas 2003), and so are compatible with our Perceptual Memory Hypotheses. (For an analysis, see the section of Recognition Memory below.)
In general, the findings lend little support to the existence of long-run equilibrium relationship between public expenditure and the socioeconomic variables, and the evidence does not lend support to the validity of Wagner's law in Kuwait.
There is some evidence from neuroscience in support of various elements of these hypotheses. As mentioned above, experiments with rats learning to search properly for food in an eight-armed maze support the role of the hippocampal system in transient episodic memory, but not in perceptual memory (Olton, Becker and Handelman 1979). Also, an eye blink in response to a tone can be classically conditioned without appeal to the hippocampus if the unconditioned stimulus (puff of air) immediately follows the conditioned stimulus (tone). If the unconditioned stimulus is delayed, the hippocampus (transient episodic memory) is needed (Lavond, Kim and Thompson 1993). fMRI studies indicated dissociation between possible neural correlates of PM and TEM. “Engagement of hippocampal and parahippocampal computations during learning correlated with later source recollection, but not with subsequent item recognition. In contrast, encoding activation in perirhinal cortex correlated with whether the studied item would be subsequently recognized, but failed to predict whether item recognition would be accompanied by source recollection.” (Davachi, Mitchell & Wagner 2003)