Do orangutans (<Emphasis Type="Italic">Pongo pygmaeus</Emphasis>) know when they do not remember?

Metacognition refers to the ability to monitor and control one’s own cognitive activities such as memory. Although recent studies have raised an interesting possibility that some species of nonhuman animals might possess such skills, subjects often required a numerous number of training trials to acquire the effective use of metacognitive responses. Here, five orangutans (Pongo pygmaeus) were tested whether they were able to escape spatial memory tests when they did not remember the location of preferred reward in a relatively small number of trials. The apes were presented with two identical cups, under one of which the experimenter hid a preferred reward (e.g., two grapes). The subjects were then presented with a third container, “escape response”, with which they could receive a less preferred but secure reward (e.g., one grape). The orangutans as a group significantly more likely selected the escape response when the baiting of the preferred reward was invisible (as compared to when it was visible) and when the hiding locations of the preferred reward were switched (as compared to when they remained unchanged). Even when the escape response was presented before the final presentation of the memory test, one orangutan successfully avoided the test in which she would likely err. These findings indicate that some orangutans appear to tell when they do not remember correct answers in memory tests.     

Effects of variable practice on retention and motor schema development in Down syndrome subjects

Portions of Schmidt's schema theory, the effects of variable practice on retention and ability to learn a novel motor task, were tested using Down syndrome subjects. 23 subjects ranged in mental and chronological ages from 3.0 to 5.1 yr. and 4.6 to 22 yr., respectively. IQs ranged from 32 to 62. The two throwing tasks were closed, discrete movements requiring no feedback or error detection during movement. Subjects were randomly assigned to a specific-practice, variable-practice, or control group. Specific group subjects practiced 100 trials from the test-target location. Variable-practice subjects also practiced 100 trials but from four different practice locations. The control group practiced an unrelated kicking activity. All subjects participated in identical pretests, posttests, and retention tests to assess accuracy on these throwing tasks. A standard archery target was used to score tosses. To examine the effects of practice on a novel task, two target conditions, or tasks, were employed. On Task A the subject tossed a bean bag at the archery target placed flat on the floor. For Task B, the novel task, the target was placed upright on the wall. Subjects were assigned higher scores for tosses landing closer to the center of the target. Analysis of variance indicated no significant differences between groups on Task A pretest or posttest. Significance was detected for the main effect of group for Task B. However, the Scheffé post hoc test indicated that the simple main effects were nonsignificant. This research did not support Schmidt's schema theory.(ABSTRACT TRUNCATED AT 250 WORDS)     

Context specificity of inhibitory control in dogs

Across three experiments, we explored whether a dog’s capacity for inhibitory control is stable or variable across decision-making contexts. In the social task, dogs were first exposed to the reputations of a stingy experimenter that never shared food and a generous experimenter who always shared food. In subsequent test trials, dogs were required to avoid approaching the stingy experimenter when this individual offered (but withheld) a higher-value reward than the generous experimenter did. In the A-not-B task, dogs were required to inhibit searching for food in a previously rewarded location after witnessing the food being moved from this location to a novel hiding place. In the cylinder task, dogs were required to resist approaching visible food directly (because it was behind a transparent barrier), in favor of a detour reaching response. Overall, dogs exhibited inhibitory control in all three tasks. However, individual scores were not correlated between tasks, suggesting that context has a large effect on dogs’ behavior. This result mirrors studies of humans, which have highlighted intra-individual variation in inhibitory control as a function of the decision-making context. Lastly, we observed a correlation between a subject’s age and performance on the cylinder task, corroborating previous observations of age-related decline in dogs’ executive function.     

Spatial perseveration error by alpacas (<Emphasis Type="Italic">Vicugna pacos</Emphasis>) in an A-not-B detour task

Spatial perseveration has been documented for domestic animals such as mules, donkeys, horses and dogs. However, evidence for this spatial cognition behavior among other domestic species is scarce. Alpacas have been domesticated for at least 7000 years yet their cognitive ability has not been officially reported. The present article used an A-not-B detour task to study the spatial problem-solving abilities of alpacas (Vicugna pacos) and to identify the perseveration errors, which refers to a tendency to maintain a learned route, despite having another available path. The study tested 51 alpacas, which had to pass through a gap at one end of a barrier in order to reach a reward. After one, two, three or four repeats (A trials), the gap was moved to the opposite end of the barrier (B trials). In contrast to what has been found in other domestic animals tested with the same task, the present study did not find clear evidence of spatial perseveration. Individuals’ performance in the subsequent B trials, following the change of gap location, suggests no error persistence in alpacas. Results suggest that alpacas are more flexible than other domestic animals tested with this same task, which has important implications in planning proper training for experimental designs or productive purposes. These results could contribute toward enhancing alpacas’ welfare and our understanding of their cognitive abilities.     

A nonhuman primate's expectations about object motion and destination: The importance of self-propelled movement and animacy

Human infants have considerable understanding of why objects move and what causes them to take one trajectory over another. Here, we explore the possibility that this capacity is shared with other nonhumans and present results from preferential looking time tests with a New World monkey, the cotton-top tamarin. Experiments examined whether individuals form different expectations about an object's potential capacity to change locations. Test objects were: 1) self-propelled, moving, animate; 2) self-propelled, moving, inanimate; 3) non-self-propelled, moving due to an external agent, inanimate; 4) non-self-propelled, motionless, inanimate. When category 1 objects, either a live mouse or frog, emerged from behind an occluder in a novel location, this did not affect looking time; subjects appeared to expect such changes. In contrast, when the other objects emerged in a novel location following occlusion from view, subjects looked longer than when the object emerged in the location seen prior to occlusion; such locational changes were apparently not expected. Some feature other than self-propelled motion accounts for the tamarins’ looking time responses and at least one candidate feature is whether the object is animate or inanimate.     

Covert orienting to central visual cues and sport practice relations in the development of visual attention.

This study examines the development of controlled covert orienting of visual attention, according to the age and the level of performance of tennis players. Practicers and nonpracticers age 13, 16, and 25 participated in a covert orienting task. On each trial, subjects responded to a target which appeared in one of four locations arrayed horizontally across the display. Three central cues were used: neutral, the cue did not specify in which location the target would appear; valid, the target was present in the cued location on 80% of the trials; invalid, the target was present in one of the uncued locations on the remaining 20% of the trials. The results showed that (1) practicers were not faster than nonpracticers in processing the signals, (2) observers of all ages oriented attention voluntarily to the cued locations, (3) central cues had a smaller effect on older and practiced subjects, and (4) developmental and sport practice factors had similar effects on orienting efficiency. The implications of these findings for theories of attentional development are discussed.     

Intrinsic feedback, interpolation, and the closed-loop theory

The amount of experience of a target location, or its surrounding locations, was manipulated to test Adams' (1971) prediction that the perceptual trace (stored perception of the correct response) is based on repeated sensations of the correct response. Sixteen learning trials, each followed by knowledge of results, on a linear-positioning task were permitted for all subjects. Each learning trial required movement to an adjustable physical stop. In learning condition without target experience, movements never terminated in a zone within which the target was interpolated. Other groups experienced movements terminating at the target point. The strength of the perceptual trace was inferred from the ability to move to the target during 20 test trials with the stop removed and without knowledge of the results. Slow movements could be made to a novel location equally as well as to a repeatedly practiced location.     

Gorillas’ use of the escape response in object choice memory tests

The ability to monitor and control one’s own cognitive states, metacognition, is crucial for effective learning and problem solving. Although the literature on animal metacognition has grown considerably during last 15 years, there have been few studies examining whether great apes share such introspective abilities with humans. Here, we tested whether four gorillas could meet two criteria of animal metacognition, the increase in escape responses as a function of task difficulty and the chosen-forced performance advantage. During testing, the subjects participated in a series of object choice memory tests in which a preferable reward (two grapes) was placed under one of two or three blue cups. The apes were required to correctly select the baited blue cup in this primary test. Importantly, the subjects also had an escape response (a yellow cup), where they could obtain a secure but smaller reward (one grape) without taking the memory test. Although the gorillas received a relatively small number of trials and thus experienced little training, three gorillas significantly declined the memory tests more often in difficult trials (e.g., when the location of the preferred reward conflicted with side bias) than in easy trials (e.g., when there was no such conflict). Moreover, even when objective cues were eliminated that corresponded to task difficulty, one of the successful gorillas showed evidence suggestive of improved memory performance with the help of escape response by selectively avoiding trials in which he would be likely to err before the memory test actually proceeded. Together, these findings demonstrate that at least some gorillas may be able to make optimal choices on the basis of their own memory trace strength about the location of the preferred reward.     

Visuospatial attention in schizophrenia: deficits in broad monitoring

Although selective attention is thought to be impaired in people with schizophrenia (PSZ), prior research has found no deficit in the ability to select one location and withdraw attention from another. PSZ and healthy control subjects (HCS) performed a stimulus detection task in which one, two, or all four peripheral target locations were cued. When one or two locations were cued, both PSZ and HCS responded faster when the target appeared at a cued than uncued location. However, increases in the number of validly cued locations had much more deleterious effects on performance for PSZ than HCS, especially for targets of low contrast whose detection was more dependent on attention. PSZ also responded more slowly in trials with four cued locations relative to trials with one or two invalidly cued locations. Thus, visuospatial attention deficits in schizophrenia arise when broad monitoring is required rather than when attention must be focused narrowly.     

Inhibitory and facilitatory location priming in patients with left-sided visual hemi-neglect

In visual search for pop-out targets, reaction times are facilitated when the target on the current trial appears at a previous target location, and inhibited when it appears at a previous distractor location, relative to when it appears at a previously empty (neutral) location (Maljkovic and Nakayama, Perception and Psychophysics 58:977–991, 1996). However, while normal subjects are able to positively/negatively tag selected target/rejected distractor locations to guide search on the next trial, patients with visual hemi-neglect may have a (uni- or bilateral) deficit in these functions that may contribute to their disturbed visual scanning behavior. To examine this, using a pop-out search task, the present study assessed cross-trial facilitatory and inhibitory priming in 14 patients with left-sided visual hemi-neglect and in 14 age-, education-, and IQ-matched control subjects. The group of neglect patients did show significant facilitatory and inhibitory priming. However, while control subjects exhibited balanced effects of facilitation and inhibition, inhibition was relatively reduced in magnitude in neglect patients. In particular, inhibition was virtually absent in two patients with lesions affecting superior regions of the frontal cortex, putatively encroaching on the frontal eye field of the right hemisphere. These findings provide neuropsychological evidence that facilitatory and inhibitory priming effects are based on dissociable mechanisms, consistent with Geyer et al. (Journal of Experimental Psychology: Human Perception and Performance 33:788–797, 2007).     

Pigeons can discriminate locations presented in pictures

The present experiments were designed to teach pigeons to discriminate two locations represented by color photographs. Two sets of photographs were taken at two distinctive locations on a university campus. These sets represented several standpoints at each location. For the true-discrimination group, pictures from the two locations were differentially associated with reward; for the pseudodiscrimination group, half of the views from each location were arbitrarily but consistently associated with reward. The former group acquired the discrimination much more rapidly. These birds also showed good transfer to new views from the standpoints used in training and to a new standpoint at each location not used in training. In a second experiment, another group of pigeons could terminate any training trial by pecking an “advance” key. Three of 4 subjects used this option to reduce the duration of trials in which pictures from the negative location were presented. These data suggest that pigeons can integrate views shown in pictures into a “concept” of a location. The method used here may be the experimental analogue of a common, natural process by which animals learn to identify locations.     

Reaching for the unknown: Multiple target encoding and real-time decision-making in a rapid reach task

Decision-making is central to human cognition. Fundamental to every decision is the ability to internally represent the available choices and their relative costs and benefits. The most basic and frequent decisions we make occur as our motor system chooses and executes only those actions that achieve our current goals. Although these interactions with the environment may appear effortless, this belies what must be incredibly sophisticated visuomotor decision-making processes. In order to measure how visuomotor decisions unfold in real-time, we used a unique reaching paradigm that forced participants to initiate rapid hand movements toward multiple potential targets, with only one being cued after reach onset. We show across three experiments that, in cases of target uncertainty, trajectories are spatially sensitive to the probabilistic distribution of targets within the display. Specifically, when presented with two or three target displays, subjects initiate their reaches toward an intermediary or ‘averaged’ location before correcting their trajectory in-flight to the cued target location. A control experiment suggests that our effect depends on the targets acting as potential reach locations and not as distractors. This study is the first to show that the ‘averaging’ of target-directed reaching movements depends not only on the spatial position of the targets in the display but also the probability of acting at each target location.     

Understanding of and reasoning about object–object relationships in long-tailed macaques?

Diagnostic reasoning, defined as the ability to infer unobserved causes based on the observation of their effects, is a central cognitive competency of humans. Yet, little is known about diagnostic reasoning in non-human primates, and what we know is largely restricted to the Great Apes. To track the evolutionary history of these skills within primates, we investigated long-tailed macaques’ understanding of the significance of inclinations of covers of hidden food as diagnostic indicators for the presence of an object located underneath. Subjects were confronted with choices between different objects that might cover food items. Based on their physical characteristics, the shape and orientation of the covers did or did not reveal the location of a hidden reward. For instance, hiding the reward under a solid board led to its inclination, whereas a hollow cup remained unaltered. Thus, the type of cover and the occurrence or absence of a change in their appearance could potentially be used to reason diagnostically about the location of the reward. In several experiments, the macaques were confronted with a varying number of covers and their performance was dependent on the level of complexity and on the type of change of the covers’ orientation. The macaques could use a board’s inclination to detect the reward, but failed to do so if the lack of inclination was indicative of an alternative hiding place. We suggest that the monkeys’ performance is based on a rudimentary understanding of causality, but find no good evidence for sophisticated diagnostic reasoning in this particular domain.     

Do cleaner fish learn to feed against their preference in a reverse reward contingency task?

The ability to control impulsive behaviour has been studied in animals with a standard test in which subjects need to choose the smaller of two food items in order to receive the larger one (reverse reward contingency). As a variety of mammals that have been tested so far (mostly primates) have great difficulties to solve the task, it has been proposed that it is generally cognitively demanding. However, according to an ecological approach to cognition, a species’ ability to solve the task should not depend on its general cognitive abilities but on whether its ecology causes selective pressure on the ability to restrain foraging behaviour. We tested this hypothesis using the cleaner wrasse (Labroides dimidiatus), a fish species that feeds against its preference in nature when engaging in cleaning interactions with so called ‘client fish’. None of the eight tested individuals learned to choose a non-preferred item after 200 trials. In a subsequent test, one subject learned to respond correctly in a large or none contingency task (only the choice of the small food was rewarded). After a short re-experience treatment, this individual learned to solve the reverse reward task after 30 trials. In conclusion, we did not find support for the general idea that interactions with clients prepared cleaners to quickly solve a reverse reward test. However, the results suggest that the potential to solve a reverse reward contingency may not be restricted to mammals but could be present also in a fish species in which the problem of choosing a non-preferred food over a preferred one is an ever present challenge in nature.     

The Role of Consistent Context in Rapid Movement Planning: Suboptimal Endpoint Adjustment to Changing Rewards

The authors' purpose was to determine if participants adjusted their endpoint during a rapid aiming task in the context of changing rewards and whether participants needed consistent feedback to do so. Participants aimed to a target that was overlapped by a penalty region. Participants gained points for hitting the target but lost points for hitting the penalty region. The reward value associated with target contact either changed trial to trial, reducing consistent feedback (variable condition) or changed between blocks of trials (blocked condition) with the repetition of reward value within a block increasing the consistency of feedback. Participants adjusted their endpoints with changing reward value in the blocked but not variable condition indicating consistent feedback is needed to adjust endpoint to changing rewards.     

Decreased responsiveness to reward in depression

We have interpreted the literature showing left anterior hypoactivation in depression as reflecting a decrease in approach-related motivation and behaviour among depressed subjects. In support of this model, we have previously demonstrated a decreased responsiveness to reward in subclinically depressed dysphoric subjects. The current study was designed to replicate and extend those findings. Clinically depressed subjects who met DSM-IV criteria for major depression were compared to a group of nondepressed control subjects on a verbal memory task under three monetary payoff conditions: neutral, reward, and punishment. Although control subjects changed their pattern of responding in both the reward and punishment conditions, relative to the neutral condition, so as to maximise their earnings, depressed subjects did not do so during reward. The two groups did not differ during the punishment condition. These findings provide additional evidence of a decreased responsiveness to reward in depressed individuals, and are consistent with the hypothesis that the left prefrontal hypoactivation observed in depression reflects a deficit in approach-related behaviour.     

Supporting the attentional momentum view of IOR: is attention biased to go right?

Inhibition of return (IOR) refers to the finding that individuals are slower to respond to a target presented at a previously attended location than they are to respond to a target presented at a novel location (Posner & Cohen, 1984). The attentional momentum theory is a recent view of how attention moves around the environment, and it provides an account for the IOR effect that does not rely on an inhibitory mechanism (Pratt, Spalek, & Bradshaw, 1999). The present paper supports the attentional momentum viewpoint in two ways: first, by replicating the finding that reaction times to targets at the uncued locations are not all the same (Pratt et al., 1999) and second, by showing that responses made to all locations on the cued side of fixation, and not just to the locations that attention had previously traversed, are slower than are responses made to locations on the opposite side of fixation. We also demonstrate that there is a directional bias to the IOR effect that results in the effect's being larger when attention moves in a left-to-right manner.     

Target location probability effects in visual search: an effect of sequential dependencies

Target location probability was manipulated in a visual search task. When the target was twice as likely to appear on 1 side of the display as the other, manual button-press response times were faster (Experiment 1A) and first saccades were more frequently directed (Experiment 1B) to the more probable locations. When the target appeared with equal probability at each location in this search task, performance benefited from repetition of target location in the preceding trials (Experiment 2). When the trial sequence was constrained so that target location did not repeat within a series of 4 trials, there was no longer an advantage for more probable locations (Experiment 3). The authors conclude that the search benefits for more probable locations resulted from short-term target location repetitions.     

Top-down and bottom-up attentional control: On the nature of interference from a salient distractor

In two experiments using spatial probes, we measured the temporal and spatial interactions between top-down control of attention and bottom-up interference from a salient distractor in visual search. The subjects searched for a square among circles, ignoring color. Probe response times showed that a color singleton distractor could draw attention to its location in the early stage of visual processing (before a 100-msec stimulus onset asynchrony [SOA]), but only when the color singleton distractor was located far from the target. Apparently the bottom-up activation of the singleton distractor’s location is affected early on by local interactions with nearby stimulus locations. Moreover, probe results showed that a singleton distractor did not receive attention after extended practice. These results suggest that top-down control of attention is possible at an early stage of visual processing. In the long-SOA condition (150-msec SOA), spatial attention selected the target location over distractor locations, and this tendency occurred with or without extended practice.     

Differential effects of social and non‐social reward on response inhibition in children and adolescents

An important issue in the field of clinical and developmental psychopathology is whether cognitive control processes, such as response inhibition, can be specifically enhanced by motivation. To determine whether non‐social (i.e. monetary) and social (i.e. positive facial expressions) rewards are able to differentially improve response inhibition accuracy in typically developing children and adolescents, an ‘incentive’ go/no‐go task was applied with reward contingencies for successful inhibition. In addition, the impact of children's personality traits (such as reward seeking and empathy) on monetary and social reward responsiveness was assessed in 65 boys, ages 8 to 12 years. All subjects were tested twice: At baseline, inhibitory control was assessed without reward, and then subjects were pseudorandomly assigned to one of four experimental conditions, including (1) social reward only, (2) monetary reward only, (3) mixed social and monetary reward, or (4) a retest condition without reward. Both social and non‐social reward significantly improved task performance, although larger effects were observed for monetary reward. The higher the children scored on reward seeking scales, the larger was their improvement in response inhibition, but only if monetary reward was used. In addition, there was a tendency for an association between empathic skills and benefits from social reward. These data suggest that social incentives do not have an equally strong reinforcing value as compared to financial incentives. However, different personality traits seem to determine to what extent a child profits from different types of reward. Clinical implications regarding probable hyposensitivity to social reward in subjects with autism and dysregulated reward‐seeking behaviour in children with attention‐deficit/hyperactivity disorder (ADHD) are discussed.