Octopus vulgaris Exhibits Interindividual Differences in Behavioural and Problem-Solving Performance

By presenting individual Octopus vulgaris with an extractive foraging problem with a puzzle box, we examined the possible correlation between behavioural performances (e.g., ease of adaptation to captive conditions, prevalence of neophobic and neophilic behaviours, and propensity to learn individually or by observing conspecifics), biotic (body and brain size, age, sex) and abiotic (seasonality and place of origin) factors. We found more neophilic animals showing shorter latencies to approach the puzzle box and higher probability of solving the task; also, shorter times to solve the task were correlated with better performance on the individual learning task. However, the most neophilic octopuses that approached the puzzle box more quickly did not reach the solution earlier than other individuals, suggesting that strong neophilic tendency may lead to suboptimal performance at some stages of the problem-solving process. In addition, seasonal and environmental characteristics of location of origin appear to influence the rate of expression of individual traits central to problem solving. Overall, our analysis provides new insights into the traits associated with problem solving in invertebrates and highlights the presence of adaptive mechanisms that promote population-level changes in octopuses' behavioural traits.

Cephalopod Behavior: From Neural Plasticity to Consciousness

It is only in recent decades that subjective experience - or consciousness - has become a legitimate object of scientific inquiry. As such, it represents perhaps the greatest challenge facing neuroscience today. Subsumed within this challenge is the study of subjective experience in non-human animals: a particularly difficult endeavor that becomes even more so, as one crosses the great evolutionary divide between vertebrate and invertebrate phyla. Here, we explore the possibility of consciousness in one group of invertebrates: cephalopod molluscs. We believe such a review is timely, particularly considering cephalopods' impressive learning and memory abilities, rich behavioral repertoire, and the relative complexity of their nervous systems and sensory capabilities. Indeed, in some cephalopods, these abilities are so sophisticated that they are comparable to those of some higher vertebrates. Following the criteria and framework outlined for the identification of hallmarks of consciousness in non-mammalian species, here we propose that cephalopods - particularly the octopus - provide a unique test case among invertebrates for examining the properties and conditions that, at the very least, afford a basal faculty of consciousness. These include, among others: (i) discriminatory and anticipatory behaviors indicating a strong link between perception and memory recall; (ii) the presence of neural substrates representing functional analogs of thalamus and cortex; (iii) the neurophysiological dynamics resembling the functional signatures of conscious states in mammals. We highlight the current lack of evidence as well as potentially informative areas that warrant further investigation to support the view expressed here. Finally, we identify future research directions for the study of consciousness in these tantalizing animals.

Infant rhesus macaque (Macaca mulatta) personality and subjective well-being

Infant temperament is theorized to lay the foundation for adult personality; however, many questions remain regarding personality in infancy, including the number of dimensions, extent to which they are adult-like, and their relation to other outcomes, such as mental and physical health. Here we tested whether adult-like personality dimensions are already present in infancy in a nonhuman primate species. We measured personality and subjective well-being in 7-month-old rhesus macaques (N = 55) using the Hominoid Personality Questionnaire and Subjective Well-Being Questionnaire, both of which were developed for adult primates based on human measures. Multiple human raters, who provided infants with daily care since birth, independently rated each infant. We found high interrater reliability. Results from a parallel analysis and scree plot indicated a five component structure, which, using principal components analysis, we found to be comprised of dimensions relating to Openness (e.g., curiosity, inquisitive, playfulness), Assertiveness (e.g., dominance, bullying, aggressive), Anxiety (e.g., vigilance, fearful), Friendliness (e.g., sociable, affectionate, sympathetic), and Intellect (e.g., organized, not erratic). These components are largely analogous to those in adult macaques, suggesting remarkably stable structural personality components across the lifespan. Infant macaques' subjective well-being positively correlates with Openness and Assertiveness and negatively correlated with Anxiety, similar to findings in adult macaques and other primates. Together, these findings suggest that, in macaques, infant personality dimensions may be conceptually related to adult personality and challenge the view that infant temperament may be disorganized and not as meaningful as adult personality. Further research is necessary to explore the antecedents, predictive validity, and stability of these personality components across situations and with development.

Variability in the "stereotyped" prey capture sequence of male cuttlefish (Sepia officinalis) could relate to personality differences

Studies of animal personality have shown consistent between-individual variation in behaviour in many social and non-social contexts, but hunting behaviour has been overlooked. Prey capture sequences, especially in invertebrates, are supposed to be quite invariant. In cuttlefish, the attack includes three components: attention, positioning, and seizure. The previous studies indicated some variability in these components and we quantified it under the hypothesis that it could relate to personality differences. We, therefore, analysed predation sequences of adult cuttlefish to test their association with personality traits in different contexts. Nineteen subjects were first exposed to an "alert" and a "threat" test and then given a live prey, for 10 days. Predation sequences were scored for components of the attack, locomotor and postural elements, body patterns, and number of successful tentacle ejections (i.e. seizure). PCA analysis of predatory patterns identified three dimensions accounting for 53.1%, 15.9%, and 9.6% of the variance and discriminating individuals based on "speed in catching prey", "duration of attack behaviour", and "attention to prey". Predation rate, success rate, and hunting time were significantly correlated with the first, second, and third PCA factors, respectively. Significant correlations between capture patterns and responsiveness in the alert and threat tests were found, highlighting a consistency of prey capture patterns with measures of personality in other contexts. Personality may permeate even those behaviour patterns that appear relatively invariant.

The evolution of general intelligence in all animals and machines

We strongly agree that general intelligence occurs in many animals but find the cultural intelligence hypothesis of limited usefulness. Any viable hypothesis explaining the evolution of general intelligence should be able to account for it in all species where it is known to occur, and should also predict the conditions under which we can develop machines with general intelligence as well.

The Digestive Tract of Cephalopods: Toward Non-invasive In vivo Monitoring of Its Physiology

Ensuring the health and welfare of animals in research is paramount, and the normal functioning of the digestive tract is essential for both. Here we critically assess non- or minimally-invasive techniques which may be used to assess a cephalopod's digestive tract functionality to inform health monitoring. We focus on: (i) predatory response as an indication of appetitive drive; (ii) body weight assessment and interpretation of deviations (e.g., digestive gland weight loss is disproportionate to body weight loss in starvation); (iii) oro-anal transit time requiring novel, standardized techniques to facilitate comparative studies of species and diets; (iv) defecation frequency and analysis of fecal color (diet dependent) and composition (parasites, biomarkers, and cytology); (v) digestive tract endoscopy, but passage of the esophagus through the brain is a technical challenge; (vi) high resolution ultrasound that offers the possibility of imaging the morphology of the digestive tract (e.g., food distribution, indigestible residues, obstruction) and recording contractile activity; (vii) needle biopsy (with ultrasound guidance) as a technique for investigating digestive gland biochemistry and pathology without the death of the animal. These techniques will inform the development of physiologically based assessments of health and the impact of experimental procedures. Although intended for use in the laboratory they are equally applicable to cephalopods in public display and aquaculture.

Assessment of domestic cat personality, as perceived by 416 owners, suggests six dimensions

Understanding individual behavioral differences in domestic cats could lead to improved selection when potential cat owners choose a pet with whom to share their lives, along with consequent improvements in cat welfare. Yet very few attempts have been made to elicit cat personality dimensions using the trait-based exploratory approaches applied previously, with some success, to humans and dogs. In this study, a list of over 200 adjectives used to describe cat personality was assembled. This list was refined by two focus groups. A sample of 416 adult cat owners then rated a cat they knew well on each of 118 retained words. An iterative analytical approach was used to identify 29 words which formed six personality dimensions: Playfulness, Nervousness, Amiability, Dominance, Demandingness, and Gullibility. Chronbach's alpha scores for these dimensions ranged from 0.63 to 0.8 and, together, they explained 56.08% of the total variance. Very few significant correlations were found between participant scores on the personality dimensions and descriptive variables such as owner age, cat age and owner cat-owning experience, and these were all weak to barely moderate in strength (r≤0.30). There was also only one significant group difference based on cat sex. Importantly, however, several cat personality scores were moderately (r=0.3-0.49) or strongly (r≥0.5) correlated with simple measures of satisfaction with the cat, attachment, bond quality, and the extent to which the cat was perceived to be troublesome. The results suggest that, with further validation, this scale could be used to provide a simple, tick-box, assessment of an owner's perceptions regarding a cat's personality. This may be of value in both applied and research settings.

A strong genetic correlation underlying a behavioural syndrome disappears during development because of genotype-age interactions

In animal populations, as in humans, behavioural differences between individuals that are consistent over time and across contexts are considered to reflect personality, and suites of correlated behaviours expressed by individuals are known as behavioural syndromes. Lifelong stability of behavioural syndromes is often assumed, either implicitly or explicitly. Here, we use a quantitative genetic approach to study the developmental stability of a behavioural syndrome in a wild population of blue tits. We find that a behavioural syndrome formed by a strong genetic correlation of two personality traits in nestlings disappears in adults, and we demonstrate that genotype-age interaction is the likely mechanism underlying this change during development. A behavioural syndrome may hence change during organismal development, even when personality traits seem to be strongly physiologically or functionally linked in one age group. We outline how such developmental plasticity has important ramifications for understanding the mechanistic basis as well as the evolutionary consequences of behavioural syndromes.

The cephalopod specialties: complex nervous system, learning, and cognition

While clearly of molluscan ancestry, the coleoid cephalopods are emergent within the phylum for complexity of brain and behaviour. The brain does not just have centralization of the molluscan ganglia but also contains lobes with “higher order” functions such as storage of learned information, and centres have been compared with the vertebrate cerebellum and frontal lobe. The flexible muscular hydrostat movement system theoretically has unlimited degrees of freedom, and octopuses are models for “soft movement” robots. The decentralized nervous system, particularly in the arms of octopuses, results in decision making at many levels. Free of the molluscan shell and with evolutionary pressure from the bony fishes, coleoids have evolved a specialty in cognition and they may have a simple form of consciousness. Cephalopods also have a skin display system of unmatched complexity and excellence of camouflage, also used for communication with predators and conspecifics. A cephalopod is first and foremost a learning animal, using the display system for deception, having spatial memory, personalities, and motor play. They represent an alternative model to the vertebrates for the evolution of complex brains and high intelligence, which has as yet been only partly explored.

Cephalopod neurobiology: an introduction for biologists working in other model systems

This paper concisely summarizes major aspects of cephalopod biology, behavior, and ecology providing a backdrop against which neurobiology of these animals can be interpreted. Reproduction, camouflage, motor control, memory, learning, and behavioral ecology are introduced, and thorough literature reviews of these subjects are cited for further reading. The aim of this paper is to provide a general introduction to cephalopods for use by workers currently focused on other model systems.

Personality consistency in dogs: a meta-analysis

Personality, or consistent individual differences in behavior, is well established in studies of dogs. Such consistency implies predictability of behavior, but some recent research suggests that predictability cannot be assumed. In addition, anecdotally, many dog experts believe that ‘puppy tests’ measuring behavior during the first year of a dog's life are not accurate indicators of subsequent adult behavior. Personality consistency in dogs is an important aspect of human-dog relationships (e.g., when selecting dogs suitable for substance-detection work or placement in a family). Here we perform the first comprehensive meta-analysis of studies reporting estimates of temporal consistency of dog personality. A thorough literature search identified 31 studies suitable for inclusion in our meta-analysis. Overall, we found evidence to suggest substantial consistency (r = 0.43). Furthermore, personality consistency was higher in older dogs, when behavioral assessment intervals were shorter, and when the measurement tool was exactly the same in both assessments. In puppies, aggression and submissiveness were the most consistent dimensions, while responsiveness to training, fearfulness, and sociability were the least consistent dimensions. In adult dogs, there were no dimension-based differences in consistency. There was no difference in personality consistency in dogs tested first as puppies and later as adults (e.g., ‘puppy tests’) versus dogs tested first as puppies and later again as puppies. Finally, there were no differences in consistency between working versus non-working dogs, between behavioral codings versus behavioral ratings, and between aggregate versus single measures. Implications for theory, practice, and future research are discussed.

Nonsomatotopic organization of the higher motor centers in octopus

Hyperredundant limbs with a virtually unlimited number of degrees of freedom (DOFs) pose a challenge for both biological and computational systems of motor control. In the flexible arms of the octopus, simplification strategies have evolved to reduce the number of controlled DOFs. Motor control in the octopus nervous system is hierarchically organized. A relatively small central brain integrates a huge amount of visual and tactile information from the large optic lobes and the peripheral nervous system of the arms and issues commands to lower motor centers controlling the elaborated neuromuscular system of the arms. This unique organization raises new questions on the organization of the octopus brain and whether and how it represents the rich movement repertoire. We developed a method of brain microstimulation in freely behaving animals and stimulated the higher motor centers-the basal lobes-thus inducing discrete and complex sets of movements. As stimulation strength increased, complex movements were recruited from basic components shared by different types of movement. We found no stimulation site where movements of a single arm or body part could be elicited. Discrete and complex components have no central topographical organization but are distributed over wide regions.

Nearly automatic motion capture system for tracking octopus arm movements in 3D space

Tracking animal movements in 3D space is an essential part of many biomechanical studies. The most popular technique for human motion capture uses markers placed on the skin which are tracked by a dedicated system. However, this technique may be inadequate for tracking animal movements, especially when it is impossible to attach markers to the animal's body either because of its size or shape or because of the environment in which the animal performs its movements. Attaching markers to an animal's body may also alter its behavior. Here we present a nearly automatic markerless motion capture system that overcomes these problems and successfully tracks octopus arm movements in 3D space. The system is based on three successive tracking and processing stages. The first stage uses a recently presented segmentation algorithm to detect the movement in a pair of video sequences recorded by two calibrated cameras. In the second stage, the results of the first stage are processed to produce 2D skeletal representations of the moving arm. Finally, the 2D skeletons are used to reconstruct the octopus arm movement as a sequence of 3D curves varying in time. Motion tracking, segmentation and reconstruction are especially difficult problems in the case of octopus arm movements because of the deformable, non-rigid structure of the octopus arm and the underwater environment in which it moves. Our successful results suggest that the motion-tracking system presented here may be used for tracking other elongated objects.

Cephalopod consciousness: Behavioural evidence

Behavioural evidence suggests that cephalopod molluscs may have a form of primary consciousness. First, the linkage of brain to behaviour seen in lateralization, sleep and through a developmental context is similar to that of mammals and birds. Second, cephalopods, especially octopuses, are heavily dependent on learning in response to both visual and tactile cues, and may have domain generality and form simple concepts. Third, these animals are aware of their position, both within themselves and in larger space, including having a working memory of foraging areas in the recent past. Thus if using a 'global workspace' which evaluates memory input and focuses attention is the criterion, cephalopods appear to have primary consciousness.

Octopuses (Octopus bimaculoides) and cuttlefishes (Sepia pharaonis, S. officinalis) can conditionally discriminate

In complex navigation using landmarks, an animal must discriminate between potential cues and show context (condition) sensitivity. Such conditional discrimination is considered a form of complex learning and has been associated primarily with vertebrates. We tested the hypothesis that octopuses and cuttlefish are capable of conditional discrimination. Subjects were trained in two maze configurations (the conditions) in which they were required to select one of two particular escape routes within each maze (the discrimination). Conditional discrimination could be demonstrated by selecting the correct escape route in each maze. Six of ten mud-flat octopuses (Octopus bimaculoides), 6 of 13 pharaoh cuttlefish (Sepia pharaonis), and one of four common cuttlefish (S. officinalis) demonstrated conditional discrimination by successfully solving both mazes. These experiments demonstrate that cephalopods are capable of conditional discrimination and extend the limits of invertebrate complex learning.

Signaling to the enemy? Body pattern expression and its response to external cues during hunting in the cuttlefish Sepia officinalis (Cephalopoda)

Cuttlefish can rapidly alter their appearance by using neurally controlled chromatophore organs. This ability may provide a window into their cognitive capacity. We test whether the changes in body pattern that occur during hunting depend on context. If they do, then it may be possible to use these changes to study cephalopod cognition while the animal is engaged in ecologically relevant tasks. We found consistent individual differences in the tendency of cuttlefish to hunt with the first two arms raised. We also found that cuttlefish usually darken their skin after they seize a prey item. This darkening is observed regardless of the identity of the prey (fish, crab, or shrimp), prey context (buried in sand, in a bare tank, or on top of a rock pile), or the presence of a sudden stimulus. The sudden stimulus was created by presenting an overhead model bird to the cuttlefish. The model induced components of the Deimatic Display, which is a form of antipredator behavior, suggesting that the model was perceived as a potential threat. Passing Cloud displays and the Darkening of the arms were significantly reduced after exposure to the model bird. The effect of a potential predator on body pattern expression during hunting suggests it may be possible to use these changes as a sensitive indicator of ecologically relevant learning.

When do octopuses play? Effects of repeated testing, object type, age, and food deprivation on object play in Octopus vulgaris

Studying play behavior in octopuses is an important step toward understanding the phylogenetic origins and function of play as well as the cognitive abilities of invertebrates. Fourteen Octopus vulgaris (7 subadults and 7 adults) were presented 2 Lego objects and 2 different food items on 7 consecutive days under 2 different levels of food deprivation. Nine subjects showed play-like behavior with the Lego objects. There was no significant difference in play-like behavior corresponding to food deprivation, age, and sex of the octopuses. The sequence of behaviors, from exploration to play-like behavior, had a significant influence on the establishment of play-like behavior, as it occurred mostly on Days 3-6 of the 7-day experiment. The pattern of development of play-like activities after a period of exploration and habituation in this study agrees with the hypothesis that object play follows object exploration. A homologous origin of this behavioral trait in vertebrates and invertebrates is highly unlikely, as the last common ancestor might not have had the cognitive capacity to possess this trait.

Links between temperamental dimensions and brain monoamines in the rat

In 27 female Wistar rats, the authors obtained composite scores on harm avoidance and novelty seeking, as well as 57 measures of monoamines and metabolites from 10 different brain regions. A multivariate regression method was used to discover associations between individual differences in temperament and neurochemistry. Harm-avoidant subjects had low levels of striatal dopamine and high levels of cortical norepinephrine and amygdaloid 5-hydroxyindoleacetic acid. High novelty-seeking scores were linked to low levels of brainstem serotonin and dopamine and to low levels of 5-hydroxyindoleacetic acid in amygdala and accumbens. Moreover, rats scoring high on novelty seeking had higher-than-average levels of norepinephrine in the thalamus and amygdala and of serotonin in the amygdala.

Personality traits in dumpling squid (Euprymna tasmanica): context-specific traits and their correlation with biological characteristics

Personality traits are a major class of behavioral variation often observed within populations of animals. However, little is known of the integration between personality and an individual's underlying biology. To address this, the authors measured personality traits in squid (Euprymna tasmanica) in 2 contexts while also describing trait correlates with biological parameters. Four traits (shy avoidance- bold aggression, activity, bury persistence, and reactivity) were reliably measured; however, trait expression between contexts was not correlated and thus was context-specific. Trait variation was not a function of gender or of somatic or reproductive condition but was explained partially by a squid's sexual maturity and its size. Results are discussed in terms of the interplay between personality variation and resulting life history strategies in animals.

Temperamental development in the rat: The first year

Behavioral continuity and change was studied in 32 (16 male) Wistar rats observed in the hole board and canopy tests, considered to measure exploration and anxiety, respectively. Subjects were tested at 6, 11, 16, 21, 37, and 52 weeks of age. In comparison to 16-week-old rats (the standard age of rats in many experiments), juveniles seemed more anxious and exploratory, whereas mature rats were more anxious and less exploratory. There was substantial behavioral consistency between week 6 and 52, the correlations being especially high between weeks 11 and 52. Principal components analyses revealed one temperamental dimension reflecting harm avoidance in juvenile and mature rats, whereas adult rats were characterized by a further dimension, reflecting novelty seeking.

A dog's got personality: a cross-species comparative approach to personality judgments in dogs and humans

This research offers a blueprint for how a cross-species comparative approach can be realized empirically. In a single design, parallel procedures and instruments were used in 2 species, dogs (Canis familiaris) and humans (Homo sapiens), to test whether personality differences exist and can be judged in dogs as accurately as in humans. Personality judgments of humans and dogs were compared on 3 accuracy criteria: internal consistency, consensus, and correspondence. Results showed that, on all 3 criteria, judgments of dogs were as accurate as judgments of humans. These findings are consistent with the evolutionary continuity hypothesis and suggest an important conclusion not widely considered by either personality or animal researchers: Personality differences do exist and can be measured in animals other than humans.

Coping strategies in male and female rats exposed to multiple stressors

Because of the pathogenic effects of chronic stress exposure, it is important to identify factors, such as effective coping strategies, that mitigate stress-induced pathology. Of interest in the present study was the consistency of behavioral responses across a diverse array of stressors. Sixteen male and 16 female Long-Evans rats were assigned to either a stress or control group. The stressed animals were subsequently exposed to a battery of ecologically relevant stressors (e.g., predator odor, novel stimuli, and immunological challenge) to determine trends in coping strategies. Blood was collected for corticosterone (CORT) assay and brains were harvested for assessment of fos immunoreactivity in the paraventricular hypothalamus (PVH) and central amygdala (CEA) following exposure to the final stressor of fox urine. A correlational analysis indicated that certain response strategies (e.g., latency to respond in different stress tests such as the open-field and novel item tests) persist across several behavioral tests, especially those tests involving exploratory components. A subsequent principal component factor analysis revealed the following four components: initiative to explore, low reactivity, variable reactivity, and high reactivity. Females exhibited higher recovery CORT levels than males; however, sex only affected one behavioral response measure (i.e., females demonstrated more attempts to climb the wall in the forced-swim test than their male counterparts). In conclusion, these results support the importance and prevalence of initiative to explore as a common factor in many stress tests; additionally, the principal component analysis indicated that physiological correlates of stress are more closely associated with more challenging environments and stimuli such as forced swimming, immunological challenges, and exposure to predator odors.