Zeitgeist

1. The spirit of the time.

2. A collection of *paradigms, beliefs, and opinions that dominates a *culture or discipline at a given period, and moulds the intellectual climate against which new findings, interpretations, ideas, and *models are judged.

'Zeitgeist' (German for 'spirit of the time') was introduced into intellectual dialectics by the Romanticism, the anti"classical cultural movement originating in late eighteenth century Europe that displayed heightened interest in nature, emotional expression, and imagination. In the beginning, the meaning of'zeitgeist' ranged from a semi-mystical force that shapes human history (Hegel 1820) to an opinionated cultural world view (Goethe 1827). Its current meaning is conveyed by definition 2 above. Occasionally the use of the term in the exact and natural sciences is considered purple prose. But what should concern us here is not whether the term itself is trendy or not, but rather what the concept tells us about the way science is practised.

It is not difficult to identify distinct zeitgeists in the history of memory research. A few examples should suffice. Introspection was the zeitgeist in the early days of psychology in Europe (Boring 1950a). "Behaviourism, the doctrine that only publicly observed behaviour is psychological datum, was the Zeitgeist in North America for a substantial part of the twentieth century. The sweeping attitude that analysis of the "rat can illuminate universal properties of brain and mind was another long-lasting Zeitgeist (e.g. Munn 1950). And the focus on memory in laboratory settings, remote from "real-life situations, is yet another example.

The zeitgeist in the neurosciences and behavioural sciences is not a coherent systematic theory or unified conceptual framework, but rather a collection of paradigms, assumptions, beliefs, and attitudes. Some are more central to the world view of the practitioners of the discipline, some less, all dominate the field, and all, or almost all, have opponents that actively oppose the mainstream or just sit there quietly harbouring the hope that the stream will divert its course. The following list is a limited selection of elements of the contemporary Zeitgeist in the science of memory (for a representative manifesto see Milner et al. 1998). Note that not always are the elements as stated here a faithful formulation of the views of those individuals who promote the Zeitgeist; rarely do they speak exactly the same language. Some of the statements are a bit exaggerated, but still, they do reflect the spirit:

1. Learning and memory are implemented in "synaptic change. Even when the proposed change involves the neuronal cell body and nucleus (Dudai and Morris 2000), the ultimate focus is still on the synapse.

2. "Long-term potentiation (LTP) = memory (e.g. Stevens 1998). There are, though, recurrent cracks in this Zeitgeist (e.g. see discussion in Shors and Matzel 1997).

3. Long-term memory = synaptic remodelling and growth ("development).

4. "Classical conditioning is the tip of the iceberg of intricate information processing in even simple brains.

5. The major natural "taxonomy of mammalian memory distinguishes explicit ("declarative) from implicit (non-declarative) memory. A bold version of this Zeitgeist claims that the classification is honoured even in primitive species without a real brain.

6. "Functional neuroimaging of the brain is bound to present us with the "engram.

There were elements of the Zeitgeist that persisted till recently but not any more. For example, that it is not productive to approach the mechanistic bases of emotional memory (for the antithesis see LeDoux 1996); or that the study of consciousness 'does not fit' serious active neuroscientists (it does, though admittedly, the growing number of publications on the subject sometimes raises the question whether this Zeitgeist was not abandoned prematurely).

What establishes a Zeitgeist? The question merits detailed analysis of specific Zeitgeist test cases, a worthy task for historians and sociologists of science (ample raw data are available, e.g. Worden et al. 1975). It is tempting, though, to suggest some possibilities. Frequently, one identifies one or a few single discoveries whose outcome can be generaliZed to a large number of problems and systems. Take LTP as an example. It suggests a cellular "model of "plasticity and learning; it can be searched for in many types of pathways and synapses in a variety of preparations and conditions; drugs that block it may be tested on multiple types of learning; many types of pharmacological congeners may be tested on LTP once the role of a certain "receptor ("glutamate) has been identified; many mutations ("neurogenetics) can be analysed for their effect on LTP, etc. etc. This creates lots of work for lots of people. The use of LTP can hence spread rather efficiently over the entire field of research on neuronal plasticity, infect multiple types of professionals, and recruit them all into the field of learning research. It is plausible to assume that some of these investigators would have not been attracted to memory research had it not been for the availability of the new cellular *assay. Success is clearly contagious, but is not enough: the recipe for a zeitgeist requires additional ingredients. It does not hurt to have dominant investigators that keep blowing the horn. And even this may not suffice. Some earlier zeitgeist may lay the ground for the development of later ones. Consider the zeitgeist notion that gene knockouts are a key to the molecular analysis of memory machinery. This idea was successfully developed in the fruit fly, *Drosophila, but the number of research groups working on memory mutants in Drosophila was never larger than five at a time. The geist reached the right zeit only when the *mouse entered the scene, because the mouse is a mammal, lots of information is available on its brain and behaviour, but, even more importantly, its brain is more relevant to ours. So here is a manifestation of another timeless zeitgeist, which clearly transcends neuroscience, namely, that we think that we are at the centre of the universe.

Whereas it might be difficult to pin-point in each case why a certain zeitgeist has prevailed, the fact that it did is easily noticed. It is reflected in the preferential acceptance of papers to trendy journals, in the selection of speakers in international conferences, and ultimately in chapters in textbooks that set the tone for the next generation. In rare cases, the zeitgeist may even prevent solid science from being published for years; the inability to publish on the properties of *conditioned taste aversion because it contradicted the zeitgeist concerning how *associative learning should behave, is an example (Garcia 1981). Furthermore, nowadays, one should watch for commercial interests in promoting the zeitgeist. Having said all that, it might seem that stating that a zeitgeist could sometimes slow down the pace of discovery may look like beating a dead horse, and that the discussion of zeitgeist is superfluous. But it is definitely not. The reason is twofold. First, dead horses often prove to be phoenixes; it wouldn't do harm to repeat the warning against conservative paradigms, dominant opinions, and overenthusiastic esprit de corps. But, second, zeitgeists carry marked benefits as well, and should not be demoted merely because they are zeitgeists. Most importantly, we shouldn't forget, they might be simply true! In addition, they attract funds. They bring in new investigators, sometimes with types of training new to the discipline (e.g. modellists into LTP, experimental psychologists into neurogenetics). They add to the cohesion of scientific communities and foster collaborations. They also promote reproduction of experiments and ultimately multiple discoveries (Ogburn and Thomas 1922; Merton 1961), all of which are critical for good science. And, almost paradoxically, they target paradigms for future revolt, which may in due time modify the zeitgeist (e.g. Boring 1950b; Chomsky 1959; Hebb 1960; Breland and Breland 1961; Neisser 1978).

The Janus face of zeitgeists hence complicates life. The personal sentiment is, as in many other cases, a function of training and personality. Some prefer the security of the zeitgeist, some the thrill of the rebellion. May be the attitude should be influenced by noting what the outcome of either conformism or revolt might be. The first risks stagnation, the latter provokes doubts and stimulates new intellectual expeditions, even if some of these end up only in *red herrings. Therefore, at least from the point of view of the scientific culture, it would be nice to keep in mind the following rule, although practise it in moderation, especially before reaching academic tenure: whatever discipline, whatever problem you are engaged in, *a priori, question thy zeitgeist.

Selected associations: Culture, Paradigm, Scoopophobia

Fig. 65 Zeitgeists in transition. In 1959, the American psychologist James Deese published two papers on human memory in two respectable professional journals. One (a; Deese 1959a) dealt with veridical memory, the other (b; Deese 1959b) with *false memory.The graph depicts the frequency of citations of these papers from their publication to the end of 1999. Until the 1990s, veridical memory was congruent with the zeitgeist of memory research; but then the Zeitgeist changed, questioning the fidelity of memories became fashionable, and Deese's paper on false memory gained popularity (arrow). The data till 1997 are adapted from Bruce and Winograd (1998), and those for 1998-99 are compiled from the Science Citation Index Expanded,Web of Science V. 4.1, ©ISI, Institute for Scientific Information. For another example of a bibliometric measure of Zeitgeist, see *LTP.

Fig. 65 Zeitgeists in transition. In 1959, the American psychologist James Deese published two papers on human memory in two respectable professional journals. One (a; Deese 1959a) dealt with veridical memory, the other (b; Deese 1959b) with *false memory.The graph depicts the frequency of citations of these papers from their publication to the end of 1999. Until the 1990s, veridical memory was congruent with the zeitgeist of memory research; but then the Zeitgeist changed, questioning the fidelity of memories became fashionable, and Deese's paper on false memory gained popularity (arrow). The data till 1997 are adapted from Bruce and Winograd (1998), and those for 1998-99 are compiled from the Science Citation Index Expanded,Web of Science V. 4.1, ©ISI, Institute for Scientific Information. For another example of a bibliometric measure of Zeitgeist, see *LTP.

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