Shared representations in body perception

The ability to understand events that happen to other people is a characteristic feature of the human mind. Here, we investigate whether the links between mental representation of one's own body and the bodies of other people could form the basis of human social representations. We studied interpersonal body representation (IBR) in a series of behavioural cueing experiments. Subjects responded to tactile events on their own body after a visual event was presented in either the corresponding anatomical location on a model's body, or in a non-corresponding location. We found that reactions were faster when the visual cue was in register with the tactile stimulation. This effect was absent when identical visual events were presented on a non-body control stimulus, suggesting a body specific mechanism for interpersonal registration of purely sensory events. Similar interpersonal systems have been demonstrated previously for the coding of action and emotion, but we believe that our results provide the first behavioural evidence for interpersonal body representation at the purely sensory level. We show that a sensory processing mechanism specific for bodies is automatically activated when viewing another person. Interpersonal body representation may be an important precursor to empathy and theory of mind. In our social world, we understand the percepts of others by registering them against the representations used to perceive our own body, and this mechanism involves an interpersonal somatotopic map.     

Audiotactile temporal order judgments

We report a series of three experiments in which participants made unspeeded 'Which modality came first?' temporal order judgments (TOJs) to pairs of auditory and tactile stimuli presented at varying stimulus onset asynchronies (SOAs) using the method of constant stimuli. The stimuli were presented from either the same or different locations in order to explore the potential effect of redundant spatial information on audiotactile temporal perception. In Experiment 1, the auditory and tactile stimuli had to be separated by nearly 80 ms for inexperienced participants to be able to judge their temporal order accurately (i.e., for the just noticeable difference (JND) to be achieved), no matter whether the stimuli were presented from the same or different spatial positions. More experienced psychophysical observers (Experiment 2) also failed to show any effect of relative spatial position on audiotactile TOJ performance, despite having much lower JNDs (40 ms) overall. A similar pattern of results was found in Experiment 3 when silent electrocutaneous stimulation was used rather than vibrotactile stimulation. Thus, relative spatial position seems to be a less important factor in determining performance for audiotactile TOJ than for other modality pairings (e.g., audiovisual and visuotactile).     

I saw it for longer than you: the relationship between perceived encoding duration and memory conformity

The memory conformity effect is when people's memories become similar to one another's following a discussion. The present study examined whether an individual's beliefs in the quality of their memory, relative to another person's, mediates susceptibility to memory conformity. Perceived encoding duration was manipulated by telling dyad members that one person had encoded a set of pictures for either half or twice as long as their partner. In fact, actual encoding duration was the same for all participants. Dyad members each encoded slightly different versions of otherwise identical pictures and discussed them prior to an individual free recall test. Participants who believed that they had encoded the pictures for half as long as their partner were more susceptible to memory conformity, as indicated by their increased tendency to report errant items at test that had been encountered from their partner rather than items that they had actually seen. This effect of perceived encoding duration on memory conformity was mediated through response order. A source monitoring test found that these unseen items were errantly attributed to the pictures approximately 50% of the time. The findings are discussed in relation to the role of metamemory in susceptibility to memory conformity.     

Olfactory-tactile compatibility effects demonstrated using a variation of the Implicit Association Test

We investigated whether the crossmodal associations between olfaction and touch reported previously in studies involving subjective report measures could also be demonstrated using an indirect measure of crossmodal association. To this end, we used a modified version of the Implicit Association Test. The participants had to make speeded discrimination responses to a series of unimodally presented olfactory (lemon vs. animal odour) or tactile stimuli (soft vs. rough fabric) using two response keys. In compatible blocks of trials, the olfactory and tactile stimuli that were mapped onto the same response key were considered to share a stronger association (e.g., the lemon odour and the soft fabric) than those that were combined onto the same response key in the incompatible blocks of trials (e.g., the animal odour and the soft fabric). The results showed that the participants responded significantly more rapidly in the compatible response mapping blocks than in the incompatible blocks, thus confirming the existence of associations between the stimuli that were considered to be compatible. These results provide the first empirical evidence that olfactory-tactile crossmodal associations are stable enough to influence performance even when not directly relevant to a participant’s task.     

Relative - not absolute - judgments of credibility affect susceptibility to misinformation conveyed during discussion

People remember different details about the same events, and when they discuss events they exchange new – and misleading – information. Discussion can change memory, especially when the source of new information is highly credible. But we do not know whether the effects of credibility are based on absolute judgments – judging a source's credibility independently from our own credibility – or relative judgments – judging a source's credibility only in relation to our own credibility. We addressed this question by manipulating subjects' expectations, leading them to believe that they either had the same, higher or lower “visual acuity” than their partner while they watched a movie together. To create ample opportunities for the pairs to mention misleading details to one another, each member unknowingly saw a different version of the movie. The pairs then discussed some of the critical differences, but not others. Later, everyone took an independent recognition test. Subjects' susceptibility to misinformation depended on their own credibility relative to their partner's, supporting the idea that susceptibility to misinformation depends on relative differences in credibility.     

Sentencing,severity, and social norms: A rank-based model of contextual influence on judgments of crimes and punishments

Context effects have been shown to bias lay people's evaluations of the severity of crimes and punishments. To investigate the cognitive mechanisms behind these effects, we develop and apply a rank-based social norms approach to judgments of perceived crime seriousness and sentence appropriateness. In Study 1, we find that (a) people believe on average that 84% of people illegally download software more than they do themselves and (b) their judged severity of, and concern about, their own illegal software downloading is predicted not by its amount but by how this amount is believed (typically inaccurately) to rank within a social comparison distribution. Studies 2 and 3 find that the judged appropriateness of a given sentence length is highly dependent on the length of other sentences available in the decision-making context: The same objective sentence was judged as approximately four times stricter when it was the second longest sentence being considered than when it was the fifth longest. It is concluded that the same mechanisms that are used to judge the magnitude of psychophysical stimuli bias judgments about legal matters.     

Comparative judgments with missing information: a regression and process tracing analysis

We had participants decide which one of two applicants was better qualified for a scholarship. They also judged the difference between them (comparative judgment). The applicants were described by features (grades) in different subjects (dimensions). The grades on some dimensions were missing (unique dimensions) for an alternative while all the grades were available on other dimensions (common dimensions). In a conventional regression analysis, we found that decision makers gave more weight to dimensions when they were common than when they were unique. However, this commensurability effect was limited to medium important dimensions and did not apply to dimensions of high or low importance. We also observed how participants retrieved information for the choice alternatives and analysed how importance and commensurability are reflected in the processing prior to the decision. Features on more important or common dimensions were inspected earlier than features on less important or unique dimensions. Participants preferred dimensional transitions and inspected features on unique dimensions longer than their common counterparts. This finding suggested that participants used inferences when features were missing. We propose an outline of a decision heuristic to describe decision making with missing information.     

Introspective duration estimation of reactive and proactive motor responses

The metajudgment of motor responses refers to our ability to evaluate the accuracy of our own actions. Can humans metajudge the duration of their Reaction Times (RTs) to a light-flash and the accuracy of their reproduction of a reference time interval bounded by two light flashes (Anticipatory Response Time, ART)? A series of four distinct experiments shows that RT_Meta and ART_Metajudgments are possible but with accuracies about ×2.4 and ×3 poorer than the corresponding RT and ART ones. In order to reveal the origin of this drop in performance, we ask whether a visual feedback synchronous with subjects’ key-presses could improve performance. We show that overall the presence of a visual feedback does not significantly improve metajudgment accuracy although such a trend is noticeable in ART_Meta. We then compare these performances with the passive perceptual estimation of the played back (Pb) RT and ART time intervals when bounded by two (RT_Pb) and three (ART_Pb) light flashes. We show that RT_Meta and RT_Pb accuracies are close to equal, but that ART_Meta is about ×2 less accurate than ART_Pb which in turn is ×1.5 less accurate than ART. The latter observation fails however to reach statistical significance hence not sustaining proposals that active time estimation is more reliable than passive one. The whole dataset is accounted for by a clock-type model where duration estimation performance is limited by four noise sources (visual, clock-count, motor and proprioceptive + efference copy) plus one proper to ART_Meta task. It is proposed that the latter reflects the impossibility for the time-counting system to use the same time origin more than once.     

Transformation of task components into an integrated representation during task switching

We combined task switching with a change paradigm to trace the transformation of the information conveyed by task cues into a readiness to perform the cued task. The tasks were composed of two components that allowed us to determine switch costs as a function of the number of changed task components. With a short stimulus-onset asynchrony (SOA) of 200ms, switch costs grew monotonically as a function of the number of changed components. With a SOA of 400ms, the switch-cost profile exhibited a nonmonotonic characteristic that was previously observed only with switches from an already performed task. Our observations suggest that task preparation can be considered as a process by which an unstructured representation of task components is gradually transformed into an integrated task representation that comprises asymmetrical associations between the task components.     

Spanish-English L2 speakers' use of subcategorization bias information in the resolution of temporary ambiguity during second language reading

Using a self-paced moving window reading paradigm, we examine the degree to which structural commitments made while 60 Spanish-English L2 speakers read syntactically ambiguous sentences in their second language (L2) are constrained by the verb's lexical entry about its preferred structural environment (i.e., subcategorization bias). The ambiguity under investigation arises because a noun phrase immediately following a verb can be parsed as either the direct object of the verb 'The CIA director confirmed the rumor when he testified before Congress', or as the subject of an embedded complement 'The CIA director confirmed the rumor could mean a security leak'. In an experiment with 59 monolingual English participants, we replicate the findings reported in the previous literature demonstrating that native speakers are guided by subcategorization bias information during sentence interpretation. In a bilingual experiment, we then show that L2 subcategorization biases influence L2 sentence interpretation. The results indicate that L2 speakers keep track of the relative frequencies of verb-subcategorization alternatives and use this information when building structure in the L2.     

Amplitude and target diameter in motor programming of discrete, rapid aimed movements: Fitts and Peterson (1964) and Klapp (1975) revisited

The reports by Fitts and Peterson [J. Exp. Psychol. 67(2) (1964) 103-113] and Klapp [J. Exp. Psychol. Hum. Percept. Perform. 104(2) (1975) 147-153] concerning the effects of movement amplitude and target diameter on reaction time present conflicting results. Fitts and Peterson reported that reaction time increased when movement amplitude was lengthened. Klapp reported an interaction in which target diameter effect on reaction time was moderated by movement length: for small targets, reaction time decreased with increasing movement length but reaction time remained unchanged (or increased modestly) when target diameter was large. Two experiments were conducted to replicate and examine the inconsistency in the reaction time results. For both experiments movement time results were in agreement with the predictions of Fitts' law. However, the results for reaction time were mixed: support was obtained for Klapp (1975) but not for Fitts and Peterson (1964). Further analysis identified several potential variables that could have influenced reaction time and explained the different effects on reaction time reported by Fitts and Peterson (1964) and Klapp (1975). The potential variables could include: limb posture at the start of a response; number of limb segments required to perform the task; and the effect of pooling reaction time data from targets located right and left of the start point, and from near and far targets.     

Assessing the influence of schematic drawings of body parts on tactile discrimination performance using the crossmodal congruency task

Seeing one's own body (either directly or indirectly) can influence visuotactile crossmodal interactions. Recently, it has been shown that even viewing a simple line drawing of a hand can also modulate such crossmodal interactions, as if the picture of the hand somehow corresponds to (or primes) the participants' own hand. Alternatively, however, it could be argued that the modulatory effects of viewing the picture of a hand on visuotactile interactions might simply be attributed to cognitive processes such as the semantic referral to the relevant body part or to the orientation cues provided by the hand picture instead. In the present study, we evaluated these various different interpretations of the hand picture effect. Participants made speeded discrimination responses to the location of brief vibrotactile targets presented to either the tip or base of their forefinger, while trying to ignore simultaneously-presented visual distractors presented to either side of central fixation. We compared the modulatory effect of the picture of a hand with that seen when the visual distractors were presented next to words describing the tip and base of the forefinger (Experiment 1), or were superimposed over arrows which provided another kind of directional cue (Experiment 2). Tactile discrimination performance was modulated in the hand picture condition, but not in the word or arrow conditions. These results therefore suggest that visuotactile interactions are specifically modulated by the image of the hand rather than by cognitive cues such as simply semantic referral to the relevant body sites and/or any visual orientation cues provided by the picture of a hand.     

The effects of verbal cueing on implicit hand maps

The use of position sense to perceive the external spatial location of the body requires that immediate proprioceptive afferent signals be combined with stored representations of body size and shape. Longo and Haggard (2010) developed a method to isolate and measure this representation in which participants judge the location of several landmarks on their occluded hand. The relative location of judgements is used to construct a perceptual map of hand shape. Studies using this paradigm have revealed large, and highly stereotyped, distortions of the hand, which is represented as wider than it actually is and with shortened fingers. Previous studies using this paradigm have cued participants to respond by giving verbal labels of the knuckles and fingertips. A recent study has shown differential effects of verbal and tactile cueing of localisation judgements about bodily landmarks (Cardinali et al., 2011). The present study therefore investigated implicit hand maps measuring through localisation judgements made in response to verbal labels and tactile stimuli applied to the same landmarks. The characteristic set of distortions of hand size and shape were clearly apparent in both conditions, indicating that the distortions reported previously are not an artefact of the use of verbal cues. However, there were also differences in the magnitude of distortions between conditions, suggesting that the use of verbal cues may alter the representation of the body underlying position sense.     

Automaticity for numerical magnitude of two-digit Arabic numbers in children

This paper examines the automatic processing of the numerical magnitude of two-digit Arabic numbers using a Stroop-like task in school-aged children. Second, third, and fourth graders performed physical size judgments on pairs of two-digit numbers varying on both physical and numerical dimensions. To investigate the importance of synchrony between the speed of processing of the numerical magnitude and the physical dimensions on the size congruity effect (SCE), we used masked priming: numerical magnitude was subliminally primed in half of the trials, while neutral priming was used in the other half. The results indicate a SCE in physical judgments, providing the evidence of automatic access to the magnitude of two-digit numbers in children. This effect was modulated by the priming type, as a SCE only appeared when the numerical magnitude was primed. This suggests that young children needed a relative synchronization of numerical and physical dimensions to access the magnitude of two-digit numbers automatically.     

An evaluation of the minimal constraining information during observation for movement reproduction

An important question in the field of imitation is what information is used for movement reproduction. While it is argued that relative motion information is perceived and minimised, direct evidence is lacking. In this experiment relative motion was manipulated to convey a novel kicking action. Twenty-four adults were assigned to one of the three impoverished relative motion display groups showing only the TOE, FOOT or LEG. After practise with partial information, participants watched a full-body display and in a final condition performed the action with an additional context constraint (i.e., a ball). Movement kinematics were collected and difference scores between participants and the model were analysed. The groups did not differ in terms of knee-ankle coordination. For hip-knee, the TOE group performed more like the model than the FOOT and LEG group. When transferred to the full-body display, there were no significant improvements. End-point trajectory information can provide sufficient information to reproduce key characteristics of the movement form.     

Resolution of conflicts between internal and external information sources on a time reproduction task: the role of perceived information reliability and attributional style

Erroneous knowledge of results (KR) that conflicts with other internal or external information sources is preferentially used and misguides performance on motor and mental timing tasks. Buekers et al. [J. Motor Behavior 26 (1994) 27] hypothesized that KR is used preferentially because participants deem it to be the most reliable information source. We tested this hypothesis in two experiments. We manipulated subjective reliability of information and information content and demonstrated that both reliability and content are assessed and used. In a third experiment we examined whether attributional style affected the use of internal and external information. While KR was present, attributional style was unrelated to performance. However, when erroneous KR was withdrawn, participants who scored high in internal attributional style or high in controllability showed more accurate performance. Whereas evaluation of information quality is explicit, information provided by the KR, whether accurate or not, may influence both implicit and explicit aspects of the tasks.     

Context-specific control and context selection in conflict tasks

This study investigated whether participants prefer contexts with relatively little cognitive conflict and whether this preference is related to context-specific control. A conflict selection task was administered in which participants had to choose between two categories that contained different levels of conflict. One category was associated with 80% congruent Stroop trials and 20% incongruent Stroop trials, while the other category was associated with only 20% congruent Stroop trials and 80% incongruent Stroop trials. As predicted, participants selected the low-conflict category more frequently, indicating that participants avoid contexts with high-conflict likelihood. Furthermore, we predicted a correlation between this preference for the low-conflict category and the control implementation associated with the categories (i.e., context-specific proportion congruency effect, CSPC effect). Results however did not show such a correlation, thereby failing to support a relationship between context control and context selection.     

Shared and distinct factors driving attention and temporal processing across modalities

In addition to the classic finding that “sounds are judged longer than lights,” the timing of auditory stimuli is often more precise and accurate than is the timing of visual stimuli. In cognitive models of temporal processing, these modality differences are explained by positing that auditory stimuli more automatically capture and hold attention, more efficiently closing an attentional switch that allows the accumulation of pulses marking the passage of time (Penney, Gibbon, & Meck, 2000). However, attention is a multifaceted construct, and there has been little attempt to determine which aspects of attention may be related to modality effects. We used visual and auditory versions of the Continuous Temporal Expectancy Task (CTET; O'Connell et al., 2009) a timing task previously linked to behavioral and electrophysiological measures of mind-wandering and attention lapses, and tested participants with or without the presence of a video distractor. Performance in the auditory condition was generally superior to that in the visual condition, replicating standard results in the timing literature. The auditory modality was also less affected by declines in sustained attention indexed by declines in performance over time. In contrast, distraction had an equivalent impact on performance in the two modalities. Analysis of individual differences in performance revealed further differences between the two modalities: Poor performance in the auditory condition was primarily related to boredom whereas poor performance in the visual condition was primarily related to distractibility. These results suggest that: 1) challenges to different aspects of attention reveal both modality-specific and nonspecific effects on temporal processing, and 2) different factors drive individual differences when testing across modalities.     

Infant development of configural object processing in visual and visual-haptic contexts

Infants’ visual processing of objects is characterised by a developmental trend from a predominantly analytical to a configural processing mode. In two studies with 6- and 8-month-old infants, we sought to replicate this finding in a purely visual condition (inspecting objects), and to examine how far redundant visual-haptic information present in a visual-haptic condition influences the processing mode. Infants were familiarized with two objects differing in three dimensions (texture, size and shape). At test, infants were presented with a familiar object, a switch object consisting of a recombination of familiar dimensions, and a novel object, and looking times were measured. Results indicate a transition from analytical processing at 6 months to configural processing at 8 months in the visual condition. In the visual-haptic condition, both age-groups displayed configural processing. Thus, redundant visual-haptic information seems to enhance object processing.     

Shared structural and temporal integration resources for music and arithmetic processing

While previous research has investigated the relationship either between language and music processing or between language and arithmetic processing, the present study investigated the relationship between music and arithmetic processing. Rule-governed number series, with the final number being a correct or incorrect series ending, were visually presented in synchrony with musical sequences, with the final chord functioning as the expected tonic or the less-expected subdominant chord (i.e., tonal function manipulation). Participants were asked to judge the correctness of the final number as quickly and accurately as possible. The results revealed an interaction between the processing of series ending and the processing of the task-irrelevant chords' tonal function, thus suggesting that music and arithmetic processing share cognitive resources. These findings are discussed in terms of general temporal and structural integration resources for linguistic and non-linguistic rule-governed sequences.