Spotting animals in natural scenes: efficiency of humans and monkeys at very low contrasts

The ability of monkeys to categorize objects in visual stimuli such as natural scenes might rely on sets of low-level visual cues without any underlying conceptual abilities. Using a go/no-go rapid animal/non-animal categorization task with briefly flashed achromatic natural scenes, we show that both human and monkey performance is very robust to large variations of stimulus luminance and contrast. When mean luminance was increased or decreased by 25–50%, accuracy and speed impairments were small. The largest impairment was found at the highest luminance value with monkeys being mainly impaired in accuracy (drop of 6% correct vs. <1.5% in humans), whereas humans were mainly impaired in reaction time (20 ms increase in median reaction time vs. 4 ms in monkeys). Contrast reductions induced a large deterioration of image definition, but performance was again remarkably robust. Subjects scored well above chance level, even when the contrast was only 12% of the original photographs (≈81% correct in monkeys; ≈79% correct in humans). Accuracy decreased with contrast reduction but only reached chance level -in both species- for the most extreme condition, when only 3% of the original contrast remained. A progressive reaction time increase was observed that reached 72 ms in monkeys and 66 ms in humans. These results demonstrate the remarkable robustness of the primate visual system in processing objects in natural scenes with large random variations in luminance and contrast. They illustrate the similarity with which performance is impaired in monkeys and humans with such stimulus manipulations. They finally show that in an animal categorization task, the performance of both monkeys and humans is largely independent of cues relying on global luminance or the fine definition of stimuli.     

Intention in motor learning through observation

The purpose of this experiment was to assess whether learning an action through observation is enhanced by the intention to reproduce the observed behaviour. Two groups of participants observed a model practise a timing task and performed a 24-hour delayed retention test. Participants in the first group of observers were explicitly instructed that they would be required to execute the timing task that they had observed as accurately as possible during the delayed retention test. Observers in the second group were instructed that they would be required to describe as accurately as possible the behaviour that they had observed. A control group of participants, who did not observe the model, was also administered the delayed retention test. The results of the retention test indicated that absolute timing (parameterization) was learned by the observers to the same extent with or without intention to reproduce the task. Indeed, on the retention test absolute timing for the two groups of observers was as effective as that for the models. However, observing with an intention to reproduce the task was beneficial for learning the movement's relative timing structure. Results are discussed with respect to a potential mechanism by which intention enhances observation.     

Identity recognition and happy and sad facial expression recall: Influence of depressive symptoms

Relatively few studies have examined memory bias for social stimuli in depression or dysphoria. The aim of this study was to investigate the influence of depressive symptoms on memory for facial information. A total of 234 participants completed the Beck Depression Inventory II and a task examining memory for facial identity and expression of happy and sad faces. For both facial identity and expression, the recollective experience was measured with the Remember/Know/Guess procedure (Gardiner & Richardson-Klavehn, 2000). The results show no major association between depressive symptoms and memory for identities. However, dysphoric individuals consciously recalled (Remember responses) more sad facial expressions than non-dysphoric individuals. These findings suggest that sad facial expressions led to more elaborate encoding, and thereby better recollection, in dysphoric individuals.     

Memory,Future Thinking,and the Self. In Honour of Martial Van Der Linden

Over the past 20 years, much progress has been made in understanding the relations between memory and future thinking, and their role in shaping our sense of self and identity. My own interest in these research questions owes much to Martial Van der Linden, with whom I had the chance to interact closely for several years. The purpose of this article is to pay tribute to him by reviewing the work we initiated together on autobiographical memory and future-oriented thinking. I first review our early work on the relationship between memory and future thinking and discuss their role in self-representation. Then, I provide an overview of the underlying neural bases and describe the alterations of autobiographical thinking that characterize certain psychological disorders. Finally, I outline an integrative framework that I recently proposed to account for the cognitive structure of past and future autobiographical thinking.     

Remembering pride and shame: self-enhancement and the phenomenology of autobiographical memory

People's self-images are grounded in autobiographical memories and, in particular, in the phenomenological experience associated with remembering. The desire to increase or maintain the positivity of the self-image (i.e., the self-enhancement motive) might thus play an important role in shaping memory phenomenology. This study examined this hypothesis by asking participants to recall positive and negative events that involve self-evaluations (i.e., pride and shame) and positive and negative events that involve evaluations about others (i.e., admiration and contempt); various phenomenological characteristics (e.g., sensory details, feeling of re-experiencing) were assessed using rating scales. The results show a positivity bias (i.e., subjectively remembering positive events with more details than negative events) for events that involve self-evaluations but not for events that involve evaluations of others. In addition, this bias was stronger for people high in self-esteem. It is concluded that biases affecting the phenomenology of autobiographical memory are part of the arsenal of psychological mechanisms people use to maintain a positive self-image.     

Effects of mental imagery styles on shoulder and hip rotations during preparation of pirouettes

To analyze individual behavior in spatial navigation especially for pirouette preparations (complete whole-body rotations), the authors studied horizontal shoulder-hip interactions under 2 constraints: postural (right and left supporting legs [SL]) and spatial (clockwise [CW] and counterclockwise [CCW]). They performed kinematic analysis at the start and end of the shoulder-hip horizontal rotations (run-up) with regard to imagery of motor actions. On the basis of the Vividness of Movement Imagery Questionnaire, they classified 8 female expert ballet dancers and 7 untrained female participants according to their movement imagery style (kinesthetic and visual). At the run-up's end, the shoulders initiated the turn independently of SL but differently depending on training: CW for dancers and CCW for untrained participants (their commonly used direction). Kinesthetic and mixed imagery styles prevailed in dancers, whereas simply a mixed style appeared among untrained participants. Thus, dance training enhances the imagery of kinesthetic sensation and influences the choice of spatial direction, facilitating the body-space interaction.     

Painful semantic context modulates the relationship between action words and biological movement perception

Studies have revealed a close relationship between action–word processing and the detection of point-light biological movements and that this effect can be modulated by the context of action-verb presentation. The goal of the present study was to further examine the extent to which motor representation activation plays a role in this relationship by testing the influence of painless/painful sentence understanding during a listening task. Participants judged the presence or absence of a point-light biological movement that was embedded in a scrambled mask after a congruent or incongruent action sentence was presented. The sentences varied according to the context of action-verb presentation (painful, painless). Perceptual judgments of human movements improved after a prior presentation of a congruent action sentence but only in the painless context. Thus, our findings show that pain included in a semantic context of sentence presentation can preclude the relationship between action–word understanding and point-light biological movement judgments.     

Finger-number interaction: an ideomotor account

Recent findings have shown that processing numerical magnitude may interact with finger movements through goal-directed movements. Here we tested these number-finger interactions in a response-effect (R-E) paradigm. During a learning phase, participants read meaningless consonant-vowel (CV) syllables immediately followed by unrelated opening or closing finger movements; during a transfer test, they again named these CV syllables in response to processing a small or a large number. The results showed that responding to a large magnitude number during the transfer phase was slower in an incompatible situation, that is, when the answer was the CV syllable that had been associated to a grip closure during the learning phase. This interference effect demonstrates that ideomotor principles can account for the link between the meaning of numbers and the perception of actions through an anticipated-magnitude code.     

Frequency,characteristics and functions of future‐oriented thoughts in daily life

Despite the growing interest in future‐oriented cognition in various areas of psychology, there is still little empirical data regarding the occurrence and nature of future‐oriented thoughts in daily life. In this study, participants recorded future‐oriented thoughts occurring in natural settings and rated their characteristics and functions. The results show that future‐oriented thoughts occur frequently in daily life and can take different representational formats (more or less abstract), embrace various thematic contents (e.g. work, relationships) and serve a range of functions (e.g. action planning, decision making). The functions and characteristics of thoughts differed according to their temporal distance, with thoughts referring to the near future being more specific and serving action planning to a greater extent than thoughts concerning the far future. The characteristics of future thoughts were also related to affective content, with positive thoughts being more frequent, more specific, and associated with more visual images than negative thoughts. Copyright © 2009 John Wiley & Sons, Ltd.