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George, I., Cousillas, H., Richard, J. - P., & Hausberger, M. (2002). Song perception in the European starling: hemispheric specialisation and individual variations. Compt. Rend. Biol., 325(3), 197–204.
Abstract: Hemispheric specialisation for speech in humans has been well documented. The lateralisation for song production observed in songbirds is reminiscent of this hemispheric dominance. In order to investigate whether song perception is also lateralised, we made multiunit recordings of the neuronal activity in the field L of starlings during the presentation of species-specific and artificial non-specific sounds. We observed a systematic stronger activation in one hemisphere than in the other one during the playback of species-specific sounds, with inter-subject variability in the predominant hemisphere for song perception. Such an asymmetry was not observed for artificial non-specific sounds. Thus, our results suggest that, at least at the individual level, the two hemispheres of the starlings' brain perceive and process conspecific signals differently.
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Keverne, E. B. (1995). Olfactory learning. Curr. Opin. Neurobiol., 5(4), 482–488.
Abstract: Unravelling the mechanisms of learning and memory can, and should, be tackled at many levels. Discovery of the huge family of odourant receptor genes provided olfaction with `molecular' respectability similar to that afforded to the visual system. Consequently, molecular studies have dominated the olfactory literature this past year, even to the point of providing a molecular basis of olfactory perception. Needless to say, the molecular approach favours a `hard-wired' system; however, other results suggest that flexibility in the olfactory system provides for certain adaptations that are crucial to the biological needs of mammals.
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Pick, D. F., Lovell, G., Brown, S., & Dail, D. (1994). Equine color perception revisited. Appl. Anim. Behav. Sci., 42(1), 61–65.
Abstract: An attempt to replicate Grzimek (1952; Z. Tierpsychol., 27: 330-338) is reported where a Quarter-Horse mare chose between colored and gray stimuli for food reinforcement. Stimuli varied across a broad range of reflectance values. A double-blind procedure with additional controls for auditory, olfactory, tactile, and position cues was used. The subject could reliably discriminate blue (462 nm) vs. gray, and red (700 nm) vs. gray without regard to reflectance (P<0.001), but could not discriminate green (496 nm) vs. gray. It is suggested that horses are dichromats in a manner similar to swine and cattle.
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Saslow, C. A. (2002). Understanding the perceptual world of horses. Appl. Anim. Behav. Sci., 78(2-4), 209–224.
Abstract: From the viewpoint of experimental psychology, there are two problems with our current knowledge of equine perception. The first is that the behavioral and neurophysiological research in this area has enormous gaps, reflecting that this animal is not a convenient laboratory subject. The second is that the horse, having been a close companion to humans for many millennia, entrenched anecdotal wisdom is often hard to separate from scientific fact. Therefore, any summary at present of equine perception has to be provisional. The horse appears to have developed a visual system particularly sensitive to dim light and movement, it may or may not have a weak form of color vision in part of the retina, it has little binocular overlap, and its best acuity is limited to a restricted horizontal band which is aimed primarily by head/neck movements. However, the total field of view is very large. Overall, as would be expected for a prey animal, horse vision appears to have evolved more for detection of predator approach from any angle than for accurate visual identification of stationary objects, especially those seen at a distance. It is likely that, as for most mammals except the primates, horses rely more heavily on their other senses for forming a view of their world. Equine high-frequency hearing extends far above that of humans, but horses may be less able to localize the point of origin of brief sounds. The horse's capacity for chemoreception and its reliance on chemical information for identification may more closely resemble that of the dog than of the human. Its tactile sensitivity is high, and the ability of its brain and body to regulate pain perception appears to be similar to that found in other mammals. There is room for a great deal of future research in both the area of equine perception and sensory-based cognition, but for the present time persons interacting with this animal should be made aware of the importance of the sounds they make, the movements of their bodies, the way they touch the animal, and the odors they emit or carry on their clothing.
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Kendrick, K. M. (1998). Intelligent perception. Appl. Anim. Behav. Sci., 57(3-4), 213–231.
Abstract: For an animal from any species to exhibit intelligent perception it must be capable of being consciously aware of what it perceives and capable of learning from this experience. Although many organisms, and for that matter machines, are capable of rapid adaptive learning in response to perception of environmental changes, such adaptations can occur without them being consciously aware either of external stimuli or their response to them. While behavioural and neurophysiological evidence suggests that, apart from ourselves, other higher primates must also be capable of such awareness, an important central question is whether such awareness is a characteristic of primate evolution or if it also occurs in sub-primate mammals as well. In this review I will examine our behavioural and neurophysiological evidence from visual and olfactory recognition studies in the sheep to support the argument that they are likely to be aware of and learn about both social and non-social objects and that they are therefore capable of intelligent perception. However, the impact of motivational changes on these perceptual processes suggests that they may be limited in terms of both prospection and retrospection and dealing with symbolic associations.
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Wilson, D. A., & Stevenson, R. J. (2003). The fundamental role of memory in olfactory perception. Trends. Neurosci., 26(5), 243–247.
Abstract: Current emphasis on odorant physiochemical features as the basis for perception largely ignores the synthetic and experience-dependent nature of olfaction. Olfaction is synthetic, as mammals have only limited ability to identify elements within even simple odor mixtures. Furthermore, olfaction is experience-bound, as exposure alone can significantly affect the extent to which stimuli can be discriminated. We propose that early analytical processing of odors is inaccessible at the behavioral level and that all odors are initially encoded as `objects' in the piriform cortex. Moreover, we suggest that odor perception is wholly dependent on the integrity of this memory system and that its loss severely impairs normal perception.
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Heffner, R. S., & Heffner, H. E. (1986). Localization of tones by horses: use of binaural cues and the role of the superior olivary complex. Behav Neurosci, 100(1), 93–103.
Abstract: The ability of horses to use binaural time and intensity difference cues to localize sound was assessed in free-field localization tests by using pure tones. The animals were required to discriminate the locus of a single tone pip ranging in frequency from 250 Hz to 25 kHz emitted by loudspeakers located 30 degrees to the left and right of the animals' midline (60 degrees total separation). Three animals were tested with a two-choice procedure; 2 additional animals were tested with a conditioned avoidance procedure. All 5 animals were able to localize 250 Hz, 500 Hz, and 1 kHz but were completely unable to localize 2 kHz and above. Because the frequency of ambiguity for the binaural phase cue delta phi for horses in this test was calculated to be 1.5 kHz, these results indicate that horses can use binaural time differences in the form of delta phi but are unable to use binaural intensity differences. This finding was supported by an unconditioned orientation test involving 4 additional horses, which showed that horses correctly orient to a 500-Hz tone pip but not to an 8-kHz tone pip. Analysis of the superior olivary complex, the brain stem nucleus at which binaural interactions first take place, reveals that the lateral superior olive (LSO) is relatively small in the horse and lacks the laminar arrangement of bipolar cells characteristic of the LSO of most mammals that can use binaural delta I.
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Schwab, C., & Huber, L. (2006). Obey or not obey? Dogs (Canis familiaris) behave differently in response to attentional states of their owners. J Comp Psychol, 120(3), 169–175.
Abstract: Sixteen domestic dogs (Canis familiaris) were tested in a familiar context in a series of 1-min trials on how well they obeyed after being told by their owner to lie down. Food was used in 1/3 of all trials, and during the trial the owner engaged in 1 of 5 activities. The dogs behaved differently depending on the owner's attention to them. When being watched by the owner, the dogs stayed lying down most often and/or for the longest time compared with when the owner read a book, watched TV, turned his or her back on them, or left the room. These results indicate that the dogs sensed the attentional state of their owners by judging observable behavioral cues such as eye contact and eye, head, and body orientation.
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Vallortigara, G., & Rogers, L. J. (2005). Survival with an asymmetrical brain: advantages and disadvantages of cerebral lateralization. Behav Brain Sci, 28(4), 575–89; discussion 589–633.
Abstract: Recent evidence in natural and semi-natural settings has revealed a variety of left-right perceptual asymmetries among vertebrates. These include preferential use of the left or right visual hemifield during activities such as searching for food, agonistic responses, or escape from predators in animals as different as fish, amphibians, reptiles, birds, and mammals. There are obvious disadvantages in showing such directional asymmetries because relevant stimuli may be located to the animal's left or right at random; there is no a priori association between the meaning of a stimulus (e.g., its being a predator or a food item) and its being located to the animal's left or right. Moreover, other organisms (e.g., predators) could exploit the predictability of behavior that arises from population-level lateral biases. It might be argued that lateralization of function enhances cognitive capacity and efficiency of the brain, thus counteracting the ecological disadvantages of lateral biases in behavior. However, such an increase in brain efficiency could be obtained by each individual being lateralized without any need to align the direction of the asymmetry in the majority of the individuals of the population. Here we argue that the alignment of the direction of behavioral asymmetries at the population level arises as an “evolutionarily stable strategy” under “social” pressures occurring when individually asymmetrical organisms must coordinate their behavior with the behavior of other asymmetrical organisms of the same or different species.
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Friederici, A. D., & Alter, K. (2004). Lateralization of auditory language functions: a dynamic dual pathway model. Brain Lang, 89(2), 267–276.
Abstract: Spoken language comprehension requires the coordination of different subprocesses in time. After the initial acoustic analysis the system has to extract segmental information such as phonemes, syntactic elements and lexical-semantic elements as well as suprasegmental information such as accentuation and intonational phrases, i.e., prosody. According to the dynamic dual pathway model of auditory language comprehension syntactic and semantic information are primarily processed in a left hemispheric temporo-frontal pathway including separate circuits for syntactic and semantic information whereas sentence level prosody is processed in a right hemispheric temporo-frontal pathway. The relative lateralization of these functions occurs as a result of stimulus properties and processing demands. The observed interaction between syntactic and prosodic information during auditory sentence comprehension is attributed to dynamic interactions between the two hemispheres.
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