Vibrotactile timing: Are vibrotactile judgements of duration affected by repetitive stimulation?

Timing in the vibrotactile modality was explored. Previous research has shown that repetitive auditory stimulation (in the form of click-trains) and visual stimulation (in the form of flickers) can alter duration judgements in a manner consistent with a “speeding up” of an internal clock. In Experiments 1 and 2 we investigated whether repetitive vibrotactile stimulation in the form of vibration trains would also alter duration judgements of either vibrotactile stimuli or visual stimuli. Participants gave verbal estimates of the duration of vibrotactile and visual stimuli that were preceded either by five seconds of 5-Hz vibration trains, or, by a five-second period of no vibrotactile stimulation, the end of which was signalled by a single vibration pulse (control condition). The results showed that durations were overestimated in the vibrotactile train conditions relative to the control condition; however, the effects were not multiplicative (did not increase with increasing stimulus duration) and as such were not consistent with a speeding up of the internal clock, but rather with an additive attentional effect. An additional finding was that the slope of the vibrotactile psychometric (control condition) function was not significantly different from that of the visual (control condition) function, which replicates a finding from a previous cross-modal comparison of timing.     

Mechanisms of priming of pop-out: Stored representations or feature-gain modulations?

Previous research has shown that repetition of a task-relevant attention-capturing feature facilitates popout search. This priming of pop-out effect is due to some residual memory from recent trials. We explore two possible mechanisms of priming of pop-out: a top-down attentional benefit from a memory of the previous target representation that is stored in visual short-term memory (VSTM) and a bottom-up change of attentional gains from perceptual features of the previously attended target. We manipulated participants’ ability to form a memory trace in VSTM by occupying it with a distractor task and found that occupying VSTM did not interfere with priming of pop-out. We next manipulated attentional gains associated with feature values by inserting an irrelevant task between pop-out searches. We found that the color of the target from the intervening perceptual task influenced pop-out search: The current pop-out search was facilitated when the intervening task’s target matched the target color of the pop-out search. These results suggest that priming of pop-out might not be due to a memory trace of the previous targets in VSTM but, rather, might be due to changes in attentional control based on priming from relatively low-level feature representations of previously attended objects.     

Shifts of criteria or neural timing? The assumptions underlying timing perception studies

In timing perception studies, the timing of one event is usually manipulated relative to another, and participants are asked to judge if the two events were synchronous, or to judge which of the two events occurred first. Responses are analyzed to determine a measure of central tendency, which is taken as an estimate of the timing at which the two events are perceptually synchronous. When these estimates do not coincide with physical synchrony, it is often assumed that the sensory signals are asynchronous, as though the transfer of information concerning one input has been accelerated or decelerated relative to the other. Here we show that, while this is a viable interpretation, it is equally plausible that such effects are driven by shifts in the criteria used to differentiate simultaneous from asynchronous inputs. Our analyses expose important ambiguities concerning the interpretation of simultaneity judgement data, which have hitherto been underappreciated.     

Basis of recency and frequency judgements of novel faces: Generalised strength or episode-specific memories?

Evidence for generalised and episode-specific strength in judgements of recency and frequency of novel faces was investigated in two experiments. Novel faces (created using an identikit program) were presented either once or three times in either of two study sets, separated by a 4 minute (Experiment 1) or 24 hour (Experiment 2) delay. In Experiment 2, the study–test phases were preceded by a familiarisation phase in which faces were presented either with or without an occupational label (some faces were not familiarised). In both experiments, judgements of recency were consistent with greater reliance on generalised strength (an amalgamation of recency and frequency of presentation), although there was some evidence for a contribution of episode-specific information. Familiarisation had opposite effects on judgements of recency and frequency, with familiarised faces judged as having been studied more frequently (three times), but less recently (yesterday) than unfamiliarised faces. The latter result is consistent with participants discounting generalised strength when episode-specific information is inadequate.     

Basis of recency and frequency judgements of novel faces: generalised strength or episode-specific memories?

Evidence for generalised and episode-specific strength in judgements of recency and frequency of novel faces was investigated in two experiments. Novel faces (created using an identikit program) were presented either once or three times in either of two study sets, separated by a 4 minute (Experiment 1) or 24 hour (Experiment 2) delay. In Experiment 2, the study-test phases were preceded by a familiarisation phase in which faces were presented either with or without an occupational label (some faces were not familiarised). In both experiments, judgements of recency were consistent with greater reliance on generalised strength (an amalgamation of recency and frequency of presentation), although there was some evidence for a contribution of episode-specific information. Familiarisation had opposite effects on judgements of recency and frequency, with familiarised faces judged as having been studied more frequently (three times), but less recently (yesterday) than unfamiliarised faces. The latter result is consistent with participants discounting generalised strength when episode-specific information is inadequate.     

The drawbridge phenomenon: representational reasoning or perceptual preference?

Two experiments investigated whether infants would look longer at a rotating "drawbridge" that appeared to violate physical laws because they knew that it was causally impossible, as claimed by R. Baillargeon, E. S. Spelke, and S. Wasserman (1985) and R. Baillargeon (1987a). Using a habituation paradigm, they reported that infants looked longer at a display that appeared impossible (rotated 180 degrees while an obstructing box was behind it) than at one that appeared possible (rotated only 112 degrees, appearing to stop at the box). Experiment 1 eliminated habituation to 180 degree screen rotations. Still, infants looked longer at the 180 degree impossible rotations. Critically, however, infants also looked longer at possible 180 degree rotations in Experiment 2, in which no obstruction was present. Moreover, no difference in effect size was found between the 2 experiments. These findings indicate that infants' longer looking at 180 degree rotations is due to simple perceptual preference for more motion. They question R. Baillargeon's (1987a) claim that it is due to infants' representational reasoning about physically impossible object permanence events.     

Selective target processing: perceptual load or distractor salience?

Perceptual load theory (Lavie, 1995) states that participants cannot engage in focused attention when shown displays containing a low perceptual load, because attentional resources are not exhausted, whereas in high-load displays attention is always focused, because attentional resources are exhausted. An alternative "salience" hypothesis holds that the salience of distractors and not perceptual load per se determines selective attention. Three experiments were conducted to investigate the influence that target and distractor onsets and offsets have on selective processing in a standard interference task. Perceptual load theory predicts that, regardless of target or distractor presentation (onset or offset), interference from ignored distractors should occur in low-load displays only. In contrast, the salience hypothesis predicts that interference should occur when the distractor appears as an onset and would occur for distractor offsets only when the target was also an offset. Interference may even occur in highload displays if the distractor is more salient. The results supported the salience hypothesis.     

The word-detection effect: Sophisticated guessing or perceptual enhancement?

Subjects discriminate letters in words better than letters in nonwords. The sophisticated guessing hypothesis attributes this word advantage to a guessing strategy. In words, the possible letters at each letter position are constrained by letters at other positions, whereas letters in nonwords are not restricted in this manner. A critical test of this hypothesis is that if subjects are givenexplicit knowledge of the letters in nonwords before the trial, the word advantage would disappear. We investigated the effect of preknowledge of the alternatives in the word-detection effect. In the word-detection effect, subjects decide which of two character strings contains letters and which contains pseudoletters. In four experiments, subjects were more accurate with words than with nonwords, and subjects were more accurate when they were told the word or nonword before the trial. However, even with foreknowledge of the alternatives, subjects were more accurate with words than with nonwords.     

Artificial grammar learning in children: abstraction of rules or sensitivity to perceptual features?

We examined sensitivity to grammatical sequences of colors in an artificial grammar learning task in a sample of 120 children aged between 5 and 8 years. The aim of the experiment was to test whether the children would preferentially learn the specific salient features of the items they were exposed to or the rules that generated these items. The children were divided into two experimental groups (identical grammar but training items differing in their surface features) and a control group (random items). The results showed that regardless of age, participants learned the most frequent salient features of the items, as well as some kind of abstract relational information. However, the 8-year-olds presented a more complex result profile, with one of the experimental groups apparently developing sensitivity to grammatical rules. These results are discussed with reference to the main current models of implicit learning. Overall, the results provided more support for stimulus-specific processing models than for rule-based models.     

Adaptation to sensory-motor temporal misalignment: instrumental or perceptual learning?

Sensory-motor delays vary over the course of development and under different environmental conditions. Previous research has shown that humans can compensate for the resulting temporal misalignment while performing sensory-motor tasks (e.g., Cunningham, Billock, & Tsou, 2001a), but remains silent on the question of whether perceptual learning-similar to that involved in adaptation to spatial misalignment (e.g., Redding & Wallace, 1993) and in adaptation to purely intersensory misalignment (e.g., Fujisaki, Shimojo, Kashino, & Nishida, 2004)-is also involved in this adaptive response. Following an attempted replication of Cunningham et al.'s (2001a) study in a preliminary experiment, we present in this paper two experiments that demonstrate that after-effects of adaptation to temporal misalignment do not spontaneously decay. The literature on adaptation to spatial misalignment suggests that, while instrumental learning spontaneously decays in the absence of reinforcement, perceptual learning persists. Therefore our results are consistent with adaptation being effected through perceptual learning.     

Procedural interference in perceptual classification: Implicit learning or cognitive complexity?

Researchers have argued that an implicit procedural-learning system underlies performance for information integration category structures, whereas a separate explicit system underlies performance for rule-based categories. One source of evidence is a dissociation in which procedural interference harms performance in information integration structures, but not in rule-based ones. The present research provides evidence that some form of overall difficulty or category complexity lies at the root of the dissociation. The authors report studies in which procedural interference is observed for even simple rule-based structures under more sensitive testing conditions. Furthermore, the magnitude of the interference is large when the nature of the rule is made more complex. By contrast, the magnitude of interference is greatly reduced for an information integration structure that is cognitively simple. These results challenge the view that a procedural-learning system mediates performance on information integration categories, but not on rule-based ones.     

Sensitivity to social contingency or stability of interaction? Modelling the dynamics of perceptual crossing

We introduce a series of evolutionary robotics simulations that address the behaviour of individuals in socially contingent interactions. The models are based on a recent study by Auvray, Lenay and Stewart [(2006). The attribution of intentionality in a simulated environment: The case of minimalist devices. In Tenth meeting of the association for the scientific study of consciousness, Oxford, UK, 23-26 June, 2006] on tactile perceptual crossing in a minimal virtual environment. In accordance, both the empirical experiments and our simulations point out the essential character of global embodied interaction dynamics for the sensitivity to contingency to arise. Rather than being individually perceived by any of the interactors, sensitivity to contingency arises from processes of circular causality that characterise the collective dynamics. Such global dynamical aspects are frequently neglected when studying social cognition. Furthermore, our synthetic studies point out interesting aspects of the task that are not immediately obvious in the empirical data. They, in addition, generate new hypotheses for further experiments. We conclude by promoting a minimal but tractable, dynamic and embodied account to social interaction, combining synthetic and empirical findings as well as concrete predictions regarding sensorimotor strategies, the role of time-delays and robustness to perturbations in interactive dynamics.     

Age differences in implicit memory: conceptual, perceptual, or methodological?

The authors examined age differences in conceptual and perceptual implicit memory via word-fragment completion, word-stem completion, category exemplar generation, picture-fragment identification, and picture naming. Young, middle-aged, and older participants (N = 60) named pictures and words at study. Limited test exposure minimized explicit memory contamination, yielding no reliable age differences and equivalent cross-format effects. In contrast, explicit memory and neuropsychological measures produced significant age differences. In a follow-up experiment, 24 young adults were informed a priori about implicit testing. Their priming was equivalent to the main experiment, showing that test trial time restrictions limit explicit memory strategies. The authors concluded that most implicit memory processes remain stable across adulthood and suggest that explicit contamination be rigorously monitored in aging studies.     

Words and Drugs: Same Mechanisms of Action?

The therapeutic effects of words, rituals and, more in general, of the whole psychosocial context around the patient, have been investigated over the past few years by using the placebo response as a model. Today we are in a good position to study all these complex psychological factors by using a physiological and neuroscientific approach that uses modern neurobiological tools to probe different brain functions. Since a placebo is represented by the whole ritual of the therapeutic act, the main concept that has emerged today is that words and rituals may modulate the same biochemical pathways that are modulated by drugs. Most of our knowledge about these mechanisms comes from the field of pain, and represents a biomedical, psychological and philosophical enterprise that is changing the way we approach and interpret medicine, psychology and human biology. If on the one hand we know some of the mechanisms of drug action in the central nervous system, on the other we can now understand how the therapist’s words may affect different physiological functions. In fact, the placebo effect and the therapist–patient relationship can be approached by using the same biochemical, cellular and physiological tools of the materia medica. Although the responses to the therapist’s words cannot be reduced merely to the action of a single drug, this represents an epochal transition, in which the distinction between psychotherapy and pharmacotherapy is progressively getting thinner, and which helps us overcome the old dichotomy between psychology and biology.     

Commuting by car or public transportation? A social dilemma analysis of travel mode judgements

The current paper analyses judgements regarding the decision to commute by car versus public transportation in terms of a conflict between immediate self-interest and long-term collective interest (i.e. social dilemma). Extending traditional formulations of rational choice theory, the present study revealed that preferences for public transportation (i.e. the presumed cooperative option) in a standard commuting situation were enhanced not only by the belief that public transportation provided a shorter average travel time than car (i.e. the presumed noncooperative option), but also by the belief that public transportation was at least as reliable (i.e. an equal or lower variability in travel time compared to car). Moreover, paralleling prior research on experimental social dilemmas, preferences were found to be affected by a pro-social concern—the belief regarding the impact of cars on the level of environmental pollution. Our findings indicated that any combination of two such considerations (i.e. travel time, variability, and impact of cars on pollution) was m ore effective in promoting public transportation preferences than the sum of their separate effects. Finally, we obtained evidence that commuter preferences were also shaped by individual differences in social value orientations (i.e. preferences for patterns of outcomes for self and others) in that, relative to pro-self commuters, pro-social commuters exhibited greater preference for public transportation.     

Conceptualization of perceptual attributes: a special case for color?

Young children experience difficulties establishing conceptual representations of color compared with everyday objects. We argue that comparing the development of color cognition to that of familiar objects is inappropriate since color is a perceptual attribute that can be abstracted from an object and by itself lacks functional significance. Instead, we compared the recognition, perceptual saliency, and naming of color to that of three other perceptual object attributes (motion, form, and size) in 47 children aged 2 to 5 years as a function of language age. Results revealed that, although color was perceptually salient relative to the other visual attributes, no selective impairment to color cognition (recognition and naming) was found relative to the three other visual attributes tested. Thus, when the appropriate comparisons are made, we find no special delay in the development of color conceptualization. Furthermore, the striking disparity between perceptual saliency and cognition of color in our youngest age groups suggests that perceptual saliency has little influence on the conceptual development of color.     

Cognitive Mechanisms in Human Creativity: Is Variation Blind or Sighted?

It is argued that the cognitive mechanisms in human creativity are, for the most part, sighted rather than blind. The article opens with a review of attempts to apply evolutionary ideas to psychology. It continues with an argument that blind-variation ideas seem to apply well in some areas of psychology, but that the psychology of human creativity is not one of these areas. An alternative sighted-variation framework is then proposed. It is argued, nevertheless, that the blind-variation system of biological evolution itself shows emergent creative properties, even though this system does not serve as an appropriate model for human creativity.