No evidence for olfactory blocking in honeybee classical conditioning

1999 ◽  
Vol 202 (13) ◽  
pp. 1839-1854 ◽  
Author(s):  
B. Gerber ◽  
J. Ullrich

We use binary odorant compounds to investigate ‘blocking’ in honeybees which learn to associate an odorant (A-D) with a sucrose reward as the reinforcer (+). ‘Blocking’ means that learning about a stimulus B is reduced when trained in compound with a stimulus A that has previously been trained alone. Thus, reinforcement of B in these circumstances is not sufficient to induce learning. Such blocking is a frequently observed phenomenon in vertebrate learning and has also recently been reported in honeybee olfactory learning. To explain blocking, current models of conditioning include cognition-like concepts of attention or expectation which, consequently, seem also to apply to honeybees. Here, we first reproduce a blocking-like effect in an experimental design taken from the literature. We identify two confounding variables in that design and experimentally demonstrate their potential to support a blocking-like effect. After eliminating these confounding variables using a series of different training procedures, the blocking-like effect disappeared. Thus, convincing evidence for blocking in honeybee classical conditioning is at present lacking. This casts doubt on the applicability of cognition-like concepts to honeybees.

1979 ◽  
Vol 44 (3_suppl) ◽  
pp. 1311-1316
Author(s):  
Richard J. Nicholls ◽  
Victor Duch

Four groups of rats were given single-alternation training in a runway using sucrose reward and then extinguished. Only subjects given training with a short interval (10 sec.) between rewarded and nonrewarded trials and a long interval (40 min.) between nonrewarded and rewarded trials learned patterned responding. This duplicated the results found in classical conditioning with a similar manipulation. The acquisition and extinction data led to the conclusion that intertrial interval cues can be made more important than aftereffects in producing patterning with sucrose reinforcement.


Author(s):  
Francis Beauvais

The “memory of water” experiments suggested the existence of molecular-like effects without molecules. Although no convincing evidence of modifications of water – specific of biologically-active molecules – has been reported up to now, consistent changes of biological systems were nevertheless recorded. We propose an alternate explanation based on classical conditioning of the experimenter. Using a probabilistic model, we describe not only the biological system, but also the experimenter engaged in an elementary dose-response experiment. We assume that during conventional experiments involving genuine biologically-active molecules, the experimenter is involuntarily conditioned to expect a pattern, namely a relationship between descriptions (or “labels”) of experimental conditions and corresponding biological system states. The model predicts that the conditioned experimenter could continue to record the learned pattern even in the absence of the initial cause, namely the biologically-active molecules. The phenomenon is self-sustained because the observation of the expected pattern reinforces the initial conditioning. A necessary requirement is the use of a system submitted to random fluctuations with autocorrelated successive states (no forced return to the initial position). The relationship recorded by the conditioned experimenter is, however, not causal in this model because blind experiments with an “outside” supervisor lead to a loss of correlations (i.e., system states randomly associated to “labels”). In conclusion, this psychophysical model allows explaining the results of “memory of water” experiments without referring to water or another local cause. It could be extended to other scientific fields in biology, medicine and psychology when suspecting an experimenter effect.


1997 ◽  
Vol 46 (6) ◽  
pp. 345-349 ◽  
Author(s):  
RICHARD ZELLER ◽  
MARION GOOD ◽  
GENE CRANSTON ANDERSON ◽  
DENA L. ZELLER

Author(s):  
Francis Beauvais

Introduction. The “memory of water” experiments suggested the existence of molecular-like effects without molecules. Although no convincing evidence of modifications of water – specific of biologically-active molecules – has been reported, consistent changes of biological systems were nevertheless recorded. We propose an alternate explanation based on classical conditioning of the experimenter.Methods. Using a probabilistic modelling, we describe not only the biological system, but also the experimenter engaged in an elementary dose-response experiment. We assume that during conventional experiments involving genuine biologically-active molecules, the experimenter is involuntarily conditioned to expect a pattern, namely a relationship between the descriptions (or “labels”) of experimental conditions and the corresponding biological system states.Results. The modelling predicts that the conditioned observer could continue to record the learned pattern even in the absence of the initial cause, namely biologically-active molecules. The phenomenon is self-sustained since the observation of the expected pattern reinforces the initial conditioning. A necessary requirement is the use of a system submitted to random fluctuations with autocorrelated successive states (no forced return to the initial position). The relationship observed by the conditioned observer is however not causal and has a quantum-like structure. The modelling predicts also that blind experiments with an “outside” supervisor lead to a loss of correlations (i.e. system states randomly associated to “labels”). Conclusion. This psychophysical modelling allows explaining the results of “memory of water” experiments without referring to water or another local cause. It could be extended to other scientific fields in biology, medicine and psychology when an experimenter effect is suspected.


2021 ◽  
Author(s):  
Alex Rogozhnikov ◽  
Pavan Ramkumar ◽  
Saul Kato ◽  
Sean Escola

The promise of using machine learning (ML) to extract scientific insights from high dimensional datasets is tempered by the frequent presence of confounding variables, and it behooves scientists to determine whether or not a model has extracted the desired information or instead may have fallen prey to bias. Due both to features of many natural phenomena and to practical constraints of experimental design, complex bioscience datasets tend to be organized in nested hierarchies which can obfuscate the origin of a confounding effect and obviate traditional methods of confounder amelioration. We propose a simple non-parametric statistical method called the Rank-to-Group (RTG) score that can identify hierarchical confounder effects in raw data and ML-derived data embeddings. We show that RTG scores correctly assign the effects of hierarchical confounders in cases where linear methods such as regression fail. In a large public biomedical image dataset, we discover unreported effects of experimental design. We then use RTG scores to discover cross-modal correlated variability in a complex multi-phenotypic biological dataset. This approach should be of general use in experiment–analysis cycles and to ensure confounder robustness in ML models.


Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.


2018 ◽  
Vol 41 ◽  
Author(s):  
Wei Ji Ma

AbstractGiven the many types of suboptimality in perception, I ask how one should test for multiple forms of suboptimality at the same time – or, more generally, how one should compare process models that can differ in any or all of the multiple components. In analogy to factorial experimental design, I advocate for factorial model comparison.


2019 ◽  
Vol 42 ◽  
Author(s):  
J. Alfredo Blakeley-Ruiz ◽  
Carlee S. McClintock ◽  
Ralph Lydic ◽  
Helen A. Baghdoyan ◽  
James J. Choo ◽  
...  

Abstract The Hooks et al. review of microbiota-gut-brain (MGB) literature provides a constructive criticism of the general approaches encompassing MGB research. This commentary extends their review by: (a) highlighting capabilities of advanced systems-biology “-omics” techniques for microbiome research and (b) recommending that combining these high-resolution techniques with intervention-based experimental design may be the path forward for future MGB research.


1978 ◽  
Vol 48 ◽  
pp. 7-29
Author(s):  
T. E. Lutz

This review paper deals with the use of statistical methods to evaluate systematic and random errors associated with trigonometric parallaxes. First, systematic errors which arise when using trigonometric parallaxes to calibrate luminosity systems are discussed. Next, determination of the external errors of parallax measurement are reviewed. Observatory corrections are discussed. Schilt’s point, that as the causes of these systematic differences between observatories are not known the computed corrections can not be applied appropriately, is emphasized. However, modern parallax work is sufficiently accurate that it is necessary to determine observatory corrections if full use is to be made of the potential precision of the data. To this end, it is suggested that a prior experimental design is required. Past experience has shown that accidental overlap of observing programs will not suffice to determine observatory corrections which are meaningful.


Author(s):  
J. M. Barrett ◽  
P. M. Heidger

Microbodies have received extensive morphological and cytochemical investigation since they were first described by Rhodin in 1954. To our knowledge, however, all investigations of microbodies and cytoplasmic bodies of rat renal proximal tubule cells have employed immersion fixation. Tisher, et al. have shown convincing evidence of fine structural alteration of microbodies in rhesus monkey kidney following immersion fixation; these alterations were not encountered when in vivo intravascular perfusion was employed. In view of these studies, and the fact that techniques for perfusion fixation have been established specifically for the rat kidney by Maunsbach, it seemed desirable to employ perfusion fixation to study the fine structure and distribution of microbodies and cytoplasmic bodies within the rat renal proximal tubule.


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