Eye Movements to Natural Images as a Function of Sex and Personality

Women and men are different. As humans are highly visual animals, these differences should be reflected in the pattern of eye movements they make when interacting with the world. We examined fixation distributions of 52 women and men while viewing 80 natural images and found systematic differences in their spatial and temporal characteristics. The most striking of these was that women looked away and usually below many objects of interest, particularly when rating images in terms of their potency. We also found reliable differences correlated with the images ’ semantic content, the observers’ personality, and how the images were semantically evaluated. Information theoretic techniques showed that many of these differences increased with viewing time. These effects were not small: the fixations to a single action or romance film image allow the classification of the sex of an observer with 64 % accuracy. While men and women may live in the same environment, what they see in this environment is reliably different. Our findings have important implications for both past and future eye movement research while confirming the significant role individual differences play in visual attention

Ants determine their next move at rest: Motor planning and causality in complex systems

© 2016 The Authors. To find useful work to do for their colony, individual eusocial animals have to move, somehow staying attentive to relevant social information. Recent research on individual Temnothorax albipennis ants moving inside their colony’s nest found a power-law relationship between a movement’s duration and its average speed; and a universal speed profile for movements showing that they mostly fluctuate around a constant average speed. From this predictability it was inferred that movement durations are somehow determined before the movement itself. Here, we find similar results in lone T. albipennis ants exploring a large arena outside the nest, both when the arena is clean and when it contains chemical information left by previous nest-mates. This implies that these movement characteristics originate from the same individual neural and/or physiological mechanism(s), operating without immediate regard to social influences. However, the presence of pheromones and/or other cues was found to affect the inter-event speed correlations. Hence we suggest that ants’ motor planning results in intermittent response to the social environment: movement duration is adjusted in response to social information only between movements, not during them. This environmentally flexible, intermittently responsive movement behaviour points towards a spatially allocated division of labour in this species. It also prompts more general questions on collective animal movement and the role of intermittent causation from higher to lower organizational levels in the stability of complex systems

Rapidly measuring the speed of unconscious learning: amnesics learn quickly and happy people slowly

Background: We introduce a method for quickly determining the rate of implicit learning. Methodology: The task involves making a binary prediction for a probabilistic sequence over 10 minutes; from this it is possible to determine the influence of events of a different number of trials in the past on the current decision. This profile directly reflects the learning rate parameter of a large class of learning algorithms including the delta and Rescorla-Wagner rules. To illustrate the use of the method, we compare a person with amnesia with normal controls and we compare people with induced happy and sad moods. Conclusions: Learning on the task is likely both associative and implicit. We argue theoretically and demonstrate empirically that both amnesia and also transient negative moods can be associated with an especially large learning rate: People with amnesia can learn quickly and happy people slowly

A Quantitative Test of the Predicted Relationship between Countershading and Lighting Environment

Countershading, a vertical luminance gradient from a dark back to a light belly, is perhaps the most common coloration phenotype in the animal kingdom. Why? We investigated whether countershading functions as self-shadow concealment (SSC) in ruminants. We calculated “optimal” countershading for SSC by measuring illumination falling onto a model ruminant as a function of time of day and lighting environment. Calibrated images of 114 species of ruminant were compared to the countershading model, and phylogenetic analyses were used to find the best predictors of coats’ countershading characteristics. In many species, countershading was close to the model’s prediction of “optimal” countershading for SSC. Stronger countershading was associated with increased use of open lighting environments, living closer to the equator, and small body size. Abrupt transitions from dark to light tones were more common in open lighting environments but unassociated with group size or antipredator behavior. Though the SSC hypothesis prediction for stronger countershading in diurnal species was not supported and noncountershaded or reverse-countershaded species were unexpectedly common, this basic pattern of associations is explained only by the SSC hypothesis. Despite extreme variation in lighting conditions, many terrestrial animals still find protection from predation by compensating for their own shadows

A review of cuttlefish camouflage and object recognition and evidence for depth perception

Cuttlefishes of the genus Sepia produce adaptive camouflage by regulating the expression of visual features such as spots and lines, and textures including stipples and stripes. They produce the appropriate pattern for a given environment by co-ordinated expression of about 40 of these `chromatic components'. This behaviour has great flexibility, allowing the animals to produce a very large number of patterns, and hence gives unique access to cuttlefish visual perception. We have, for instance, tested their sensitivity to image parameters including spatial frequency, orientation and spatial phase. One can also ask what features in the visual environment elicit a given coloration pattern; here most work has been on the disruptive body pattern, which includes well-defined light and dark features. On 2-D backgrounds, isolated pale objects of a specific size, that have well-defined edges, elicit the disruptive pattern. Here we show that visual depth is also relevant. Naturally, cuttlefish probably use the disruptive pattern amongst discrete objects, such as pebbles. We suggest that they use several visual cues to `identify' this type of background (including: edges, contrast, size, and real and pictorial depth). To conclude we argue that the visual strategy cuttlefish use to select camouflage is fundamentally similar to human object recognition