Abstract: To examine the hypothetical role of the eyes in visual mental imagery of movement 72 undergraduate women students in psychology were asked to imagine a running horse and then to produce the same mental image without moving the eyes and the head. In 59% of the subjects interesting modifications of the imagined movement appeared: 37% observed an inhibition of the movement and 19% an evident slowing up of the moving figure. The interpretation of this result was made by hypothesizing that the eyes are concretely involved in visual imagery processes.

Abstract: Based on an intensive analysis of literature, the study summarizes problems involved in the significance of domesticated dogs as objects of instruction and assistants of the education of children. Several important topics are discussed in view of advances for children in families keeping dogs. Such topics are mainly related to a general socio-emotional level, the support of cognitive development and character formation. Further aspects are the acquisition of a sense of responsibility, and the development of self-confidence, a sense of social membership and security, as well as important attributes of character such as frankness, broad mindedness, and sympathetic understanding. Moreover, knowledge about the life cycle and functions of body organs can be conveyed, and the dog could, at least in part, substitute for brothers and sisters. Basically, positive attitudes towards animals in general, as well as nature and environment are supported. All topics are critically commented and considered to be realistic or not. The supporting role of parents, in particular, is emphasized. Parental commitment should include deep concern with the typical attributes of the dog breed desired, and optimal dog keeping conditions to prevent harm to the children. The final commentary lays special emphasis on negative features of domestication for a pet owner, and cautions against non-biological and illusionary ideas about domesticated animals.

Abstract: Leadership is not an inherent quality of animal groups that show directional locomotion. However, there are other factors that may be responsible for the occurrence of leadership in fish shoals, such as individual differences in nutritional state between group members. It appears that front fish have a strong influence on directional shoal movements and that individuals that occupy such positions are often characterised by larger body lengths and lower nutritional state. Potential interactions between the two factors and their importance for positioning within shoals need further attention. Initiation of directional movement in stationary shoals and position preferences in mobile shoals need to be addressed separately because they are potentially subject to different constraints. Individuals that initiate a swimming direction may not necessarily be capable of the sustained high swimming performance required to keep the front position or have the motivation to do so, for that matter. More empirical and theoretical work is necessary to look at the factors controlling positioning behaviour within shoals, as well as overall shoal shape and structure. Tracking of marked individuals whose positioning behaviour is monitored over extended time periods of hours or days would be useful. There is an indication that shoal positions are rotated by individuals according to their nutritional needs, with hungry fish occupying front positions only for as long as necessary to regain their nutritional balance. This suggests that shoal members effectively take turns at being leaders. There is a need for three-dimensional recordings of shoaling behaviour using high-speed video systems that allow a detailed analysis of information transfer in shoals of different size. The relationship between leadership and shoal size might provide an interesting field for future research. Most studies to date have been restricted to shoals of small and medium size and more information on larger shoals would be useful.

Abstract: The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb.

Abstract: Speed related changes in trunk mechanics have not yet been investigated, although high-speed training is currently used in the horse. To evaluate the effects of speed on back kinematics and trunk muscles activity, 4 saddle horses were recorded while trotting on a horizontal treadmill at speeds ranging from 3.5 to 6 m/s. The 3-dimensional (3-D) trajectories of skin markers on the left side of the horse and the dorsal midline of the trunk were established. Electrical activity was simultaneously obtained from the longissimus dorsi (LD) and rectus abdominis (RA) muscles using surface electrodes. Ten consecutive strides were analysed for each horse at each of the 5 velocity steps. Electromyographic and kinematic data were time-standardised to the duration of the stride cycle and compared using an analysis of variance. The back extended during the first part of each diagonal stance phase when the RA was active and the back flexed during the second part of each diagonal stance phase when the LD was active. The onset and end of muscle activity came earlier in the stride cycle and muscle activity intensity increased when speed increased. The amplitude of vertical movement of the trunk and the maximal angles of flexion decreased with increasing speed, whereas the extension angles remained unchanged. This resulted in a decreased range of back flexion-extension. This study confirms that the primary role of trunk muscles is to control the stiffness of the back rather than to induce movements. Understanding the effects of speed on the back of healthy horses is a prerequisite for the prevention and treatment of back pathology.