Unprompted recall and reporting of hidden objects by a chimpanzee (Pan troglodytes) after extended delays

The ability to recall features of environments not present to the senses is important in human thinking, planning, and communication, but to date there are almost no data on recall capabilities in nonverbal animals. In this study, the author used symbol knowledge as a tool to study chimpanzee memory. An 11-year-old female chimpanzee (Pan troglodytes) that had already learned a large number of arbitrarily designated geometric forms (lexigrams) watched as an experimenter hid an object in the woods outside her outdoor enclosure. The type and location of the object varied across trials. After an imposed delay of up to 16 h, the chimpanzee could interact indoors with a person who did not know that an object had been hidden, let alone the type or location of the object. A keyboard in the indoor cage displayed 256 lexigrams. From Trial 1, the chimpanzee seemed to do whatever it took to catch the person's attention and then touched the lexigram corresponding to the type of object hidden, pointed outdoors, went outdoors (if followed), and continued to point manually toward the object and vocalize until the person found the object. The subject indicated nonfood objects as well as more than 20 food types.     

Self‐reference and group membership: evidence for a group‐reference effect

Two experiments were designed to explore whether encoding information in reference to a group would facilitate the later recall of that information to the same extent as encoding with reference to the self. In both experiments, participants encoded adjectives with reference to the self, semantic properties, or a group and were subsequently given a surprise‐free recall test. In Experiment 1 (N = 37), the participants' university served as the reference group. In Experiment 2 (N=41), the participants' family served as the reference group. In both experiments, self‐reference resulted in better recall than semantic processing, replicating the typical self‐reference effect (SRE). More importantly, strong evidence for a group‐reference effect (GRE) was found in that group‐reference resulted in better recall than semantic processing and in fact facilitated recall to the same extent as self‐referencing. The existing explanations (schemas, organization, elaboration, mental cueing, and evaluation) for the SRE were compared with regard to their viability in accounting for the GRE patterns. We discuss additional features that may be important in the explanation of the SRE and suggest future directions for research on group‐referencing. Copyright © 2002 John Wiley & Sons, Ltd.     

Effects of response‐contingent stimulus pairing on vocalizations of nonverbal children with autism

Research on stimulus–stimulus pairing to induce novel vocalizations in nonverbal children has typically employed response‐independent pairing (RIP) procedures to condition speech sounds as reinforcers. The purpose of the present study was to evaluate the effects of a response‐contingent pairing (RCP) procedure on the vocalizations of three nonverbal boys diagnosed with autism spectrum disorder. During RCP, adult‐delivered sounds that were either paired with a preferred item (target sounds) or not (nontarget sounds) were presented contingent on a button‐press response. In Experiment 1, RCP was compared with an RIP procedure, in which the timing of sound presentations was yoked to the preceding RCP session. RCP produced a greater effect on all participants' target vocalizations than RIP. Experiment 2 demonstrated the effects of differential reinforcement of the vocalizations induced in Experiment 1. The results suggest that RCP may develop vocalizations more reliably than RIP procedures.     

Transfer between contextual conditional discriminations: an examination of how stimulus conjuctions are represented

In 2 experiments, when rats were placed in 1 pair of contexts, A and B, 2 relationships were in force (X --> food and Y --> no food), and when they were placed in another pair of contexts, C and D, the complementary relationships were operative (Y --> food and X --> no food). In Experiment 1, rats then received a 2nd discrimination that was either contextually congruent (in A and B, Y --> food and X --> no food; in C and D, X --> food and Y --> no food) or contextually incongruent (in A and D, Y --> food and X --> no food; in C and B, X --> food and Y --> no food) with the 1st discrimination. In Experiment 2, the 1st discrimination, involving X and Y, was interleaved with a 2nd discrimination, involving V and W, that was again either congruent (in A and B, V --> food and W --> no food) or incongruent (in A and D, V --> food and W --> no food) with the 1st discrimination. The congruent discriminations were acquired more readily than were the incongruent discriminations.     

Chimpanzees (Pan troglodytes) conceal visual and auditory information from others

Chimpanzees (Pan troglodytes) competed with a human for food. The human sat inside a booth, with 1 piece of food to her left and 1 to her right, which she could retract from her chimpanzee competitor's reach as needed. In Experiment 1, chimpanzees could approach either side of the booth unseen but then had to reach through 1 of 2 tunnels (1 clear, 1 opaque) for the food. In Experiment 2, both tunnels were clear and the human was looking away, but 1 of the tunnels made a loud noise when it was opened. Chimpanzees preferentially reached through the opaque tunnel in the first study and the silent tunnel in the second, successfully concealing their taking of the food from the human competitor in both cases. These results suggest that chimpanzees can, in some circumstances, actively manipulate the visual and auditory perception of others by concealing information from them.     

“Get it out the way. The wait's killing me.” hastening and hiding during soccer penalty kicks

ObjectivesIt has been suggested that hastening and hiding—rushing through penalty preparation and not looking at the goal when preparing the penalty kick—are associated with negative penalty taking performance. In the present study, we investigated how opposing players perceived these nonverbal behaviors, how they affect outcome expectations, and how they affect the behavior of opposing goalkeepers.DesignThe present study employs an experimental research design (Experiment 1: 2 (gaze behavior) × 3 (preparation time) design; Experiment 2: 2 (gaze behavior) × 2 (preparation time) design).MethodWe examined the perception of nonverbal hastening and hiding behavior using the point-light technique during the soccer penalty kick among goalkeepers (Experiment 1a; n = 20), and among outfield soccer players (Experiment 1b; n = 29). Furthermore, we analyzed how these respective penalty preparation strategies influenced the behavior of high-level goalkeepers (n = 12) under in situ conditions (Experiment 2).ResultsThe results from Experiment 1 demonstrated that penalty takers showing hastening and hiding behaviors are perceived more negatively by both soccer goalkeepers and outfield players: (i) they are considered to possess less positive attributes, (ii) to have less accuracy in their penalties, and (iii) likely to perform less well in penalty situations. Experiment 2 provided first evidence that goalkeepers initiate their movement later following the observation of hastening and hiding behaviors during the penalty preparation.ConclusionsOur findings demonstrate the importance of investigating nonverbal behavior in sports as these have a major impact on impression formation, expected performance, and actual behavior of opposing players in the soccer penalty situation.     

Effects of anesthetic agents on socially transmitted olfactory memories in mice

Mice can learn a food preference from odor cues transmitted on the breath of a conspecific, even if the “demonstrator” is anesthetized. To our knowledge there are no studies examining the effect of anesthetizing the “observer” on development of memory for socially transmitted food preferences (STFP). In Experiment 1 we found that 2–4 month-old F2 C57Bl/6x129sv male and female mice demonstrated a STFP after a 5 min exposure to an anesthetized demonstrator mouse when tested 24 h later. In Experiment 2, observer mice anesthetized with Sagatal (60 mg/kg) prior to the “social interaction” preferentially avoided the cued food when tested 24 h later. This aversion was not due to any overt aversive effects of this dose of Sagatal because mice that ate the food and were then anesthetized, or could only smell the food for 5 min while anesthetized, showed no preference or aversion. In a third experiment we found that the Sagatal-induced aversion was not a general property of anesthesia because there were varied results produced by observer mice treated with anesthetic drugs with different mechanisms of action. Vetalar (200 mg/kg) and Rompun (10 mg/kg) treated animals ate similar amounts of cued and non-cued food at test, indicating an absence of learning. Hypnorm (0.5 ml/kg) treated animals showed a preference for the cued food whereas those treated with Hypnovel (2.5 ml/kg) showed an aversion to the cued food. These results show that the food aversion observed with Sagatal is not a general property of anesthetic agents, but appears to be restricted to those acting primarily on the GABAergic system. Thus, we have shown that under certain conditions it is possible for an anesthetized observer mouse to learn a preference or aversion of a socially-linked olfactory cue.     

Uncertainty reduction, self-enhancement, and ingroup identification

Two experiments tested the prediction that uncertainty reduction and self-enhancement motivations have an interactive effect on ingroup identification. In Experiment 1 (N = 64), uncertainty and group status were manipulated, and the effect on ingroup identification was measured. As predicted, low-uncertainty participants identified more strongly with a high- than low-status group, whereas high-uncertainty participants showed no preference; and low-status group members identified more strongly under high than low uncertainty, whereas high-status group members showed no preference. Experiment 2 (N = 210) replicated Experiment 1, but with a third independent variable that manipulated how prototypical participants were of their group. As predicted, the effects obtained in Experiment 1 only emerged where participants were highly prototypical. Low prototypicality depressed identification with a low-status group under high uncertainty. The implications of these results for intergroup relations and the role of prototypicality in social identity processes are discussed.     

Working and reference memory of pigs (Sus scrofa domesticus) in a holeboard spatial discrimination task: the influence of environmental enrichment

Interest in cognitive research in pigs is increasing, but little is known about the impact of environmental conditions on pigs’ cognitive capabilities. The present study investigated the effect of environmental enrichment on cognitive performance of pigs in a holeboard spatial task, in which they had to discriminate four baited buckets out of 16. Pigs (n = 32) were either housed in stimulus-poor, barren pens, or in larger pens enriched with rooting substrates. Pigs were subjected to 30 holeboard trials. Both working memory (WM), that is, the ratio (baited visits/total number of (re)visits to baited buckets), and reference memory (RM), that is, the ratio ((re)visits to baited buckets/total number of visits to all buckets), improved over trials. WM scores were higher in pigs from enriched pens than in pigs from barren pens. Housing did not affect RM scores. Personality type of the pigs, as assessed early in life using a backtest, did not affect WM or RM. In conclusion, housing conditions of pigs did not affect reference memory, but environmental enrichment improved working memory of pigs in a spatial discrimination task. Based on the findings of this study, we suggest that cognitive functioning of pigs may be impaired under commonly used housing conditions.     

Event-related potentials during word-reading and figure-matching in left-handed and right-handed males and females

In two experiments, event-related potentials at left and right occipital, parietal, and temporal sites were studied in 16 left-handers (8 male, 8 female) and 16 right-handers (8 male, 8 female). Subjects displayed extreme handedness, had a normal writing hand position, reported no left-handed relatives, and reported no perinatal traumata. In Experiment 1, centrally presented words had to be read, and nonverbal stimuli had to be matched. Condition-dependent asymmetries were found for P340 and SW components. Word-reading elicited a N500 component, whereas figure-matching did not. In Experiment 2, words presented to either the left or right visual field had to be read. It was found that N160 measures were larger, and P240, P400, and SW measures were smaller to words presented in the contralateral visual field compared to words in the ipsilateral field. Sex affected these pathway effects. In both experiments, hand preference did not significantly influence the ERP results.     

Contingency judgments by depressed college students: sadder but not always wiser

We examined depressed and nondepressed college students' perceptions of control over outcomes in a task similar to the one introduced by Alloy and Abramson (1979, Experiment 2). In Experiment 1, when subjects completed a contingency learning task with no one else present, nondepressed subjects perceived themselves to have more control over frequently occurring response-independent outcomes than did depressed subjects, which replicated Alloy and Abramson's finding. When subjects completed the task in the presence of an observer, depressed students perceived themselves to have more control than did nondepressed students. In Experiment 2, the observer effects found in Experiment 1 were replicated, and we extended those results by showing that when response-independent outcomes occurred relatively infrequently, depressed and nondepressed subjects who completed the task in the presence of an observer did not reliably differ in their estimates of personal control. In Experiment 3, which included minor procedural variations from the other experiments, the pattern of results found in Experiments 1 and 2 was replicated under conditions in which observers were present while subjects received frequently occurring outcomes. Together, the results of the three experiments demonstrate that the consistently accurate personal control estimates of depressed subjects that have been found across a variety of situations break down when subjects complete a contingency learning task in the presence of an observer, and outcomes occur independently of response at a high frequency.     

Spatial Error Detection and Assimilation Effects in Rapid Single and Bimanual Aiming Movements

In 2 experiments, spatial error detection capability and movement accuracy were investigated in both single and bimanual rapid aiming movements. In both experiments, right-handed college-age participants (N = 40 [Experiment 1]; N = 24 [Experiment 2]) used light, aluminum levers to make quick single and dual reversal movements in the sagittal plane in a time to reversal of 210 ms to either the same or different target locations involving identical (Experiment 1) or mirror-image (Experiment 2) movements. In Experiment 1, the shorter-distance limb overshot the target by 15-23&percent; when paired with a limb traveling at least 20 degrees farther, but no spatial assimilations were shown when movements differed by 20 degrees or less. In Experiment 2, the shorter-distance limb overshot 22-29&percent; when paired with a limb traveling 20 degrees farther, but spatial assimilations were not mitigated when both limbs moved to the same target position. Participants underestimated movement amplitude in all dual conditions but particularly when spatial assimilations were noted. Correlations between actual and estimated errors decreased from single to dual trials in both experiments. The findings suggest that spatial assimilations are caused by bimanual differences in movement amplitude, regardless of movement direction, and that individuals have greater difficulty identifying errors in simultaneous actions, especially when spatial assimilations are present, than identifying errors in single-limb actions.     

Sexual harassment under social identity threat: the computer harassment paradigm

Two laboratory experiments investigated the hypothesis that threat to male identity would increase the likelihood of gender harassment. In both experiments, using the computer harassment paradigm, male university students (N=80 in Experiment 1, N=90 in Experiment 2) were exposed to different types of identity threat (legitimacy threat and threat to group value in Experiment 1 and distinctiveness threat and prototypicality threat in Experiment 2) or to no threat and were then given the opportunity to send pornographic material to a virtual female interaction partner. Results show that (a) participants harassed the female interaction partner more when they were exposed to a legitimacy, distinctiveness, or prototypicality threat than to no threat; (b) this was mainly true for highly identified males; and (c) harassment enhanced postexperimental gender identification. Results are interpreted as supporting a social identity account of gender harassment.     

Aging and retrospective revaluation of causal learning

In a 2-stage causal learning task, young and older participants first learned which foods presented in compound were followed by an allergic reaction (e.g., STEAK-BEANS→ REACTION) and then the causal efficacy of 1 food from these compounds was revalued (e.g., BEANS→ NO REACTION). In Experiment 1, unrelated food pairs were used, and although there were no age differences in compound- or single-cue-outcome learning, older adults did not retrospectively revalue the causal efficacy of the absent target cues (e.g., STEAK). However, they had weaker within-compound associations for the unrelated foods, and this may have prevented them from retrieving the representations of these cues. In Experiment 2, older adults still showed no retrospective revaluation of absent cues even though compound food cues with pre-existing associations were used (e.g., STEAK-POTATO), and they received additional learning trials. Finally, in Experiment 3, older adults revalued the causal efficacy of the target cues when small, unobtrusive icons of these cues were present during single-cue revaluation. These findings suggest that age-related deficits in causal learning for absent cues are due to ineffective associative binding and reactivation processes.     

Absorption and hypnotizability: context effects reexamined

Two independent studies failed to find evidence consistent with Council, Kirsch, and Hafner (1986), who argued that the repeatedly observed correlations between Tellegen's (1981) Absorption Scale (TAS) and hypnosis measures were artifacts of testing context, and de Groot, Gwynn, and Spanos (1988), who claimed evidence for a Gender x Context moderator effect. In the present studies, Ss completed the TAS and other personality questionnaires on 2 occasions: during an independent survey and later immediately prior to an assessment of hypnotizability. In Experiment 1 (N = 475), the effect of context on the relation between questionnaire scores and hypnotizability was weak and variable; in Experiment 2 (N = 434), these weak effects were reversed. The results reaffirm the construct validity of absorption as both a major dimension of personality and as a predictor of hypnotic responsiveness.     

Performance and learning of generalized motor programs: relative (GMP) and absolute (parameter) errors

The effects of practice (Experiment 1) and parameter variability (Experiment 2) on the learning of generalized motor programs (GMPs) and movement parameterization were investigated. In each experiment, 2 tasks with different relative force-time structures were tested. Participants (N = 32, Experiment 1; N = 40, Experiment 2) attempted to exert a pattern of force that resembled in force and time a waveform that was displayed on a computer monitor. In both experiments, the analysis suggested that the GMP, although refined over practice, was relatively stable (i.e., resistant to decay and interference), even early in practice (after 20 trials). In addition, the results indicated that constant and variable parameter practice did not differentially affect GMP learning but did degrade the learning of the parameter that was not varied. The data provided additional evidence for the dissociation of the GMP and the parameterization processes proposed in GMP theory. Contrary to schema theory, the present data suggest an interdependence between the force and the time parameters: The manipulation of 1 of the parameters has a negative effect on the learning of the other parameter.     

The Simon effect with wheel-rotation responses

The authors examined clockwise and counterclockwise wheel-rotation responses to high- or low-pitched tones presented in participants' (N = 96, Experiment 1; N = 48, Experiment 2; N = 48, Experiment 3) left and right ears. In Experiment 1, a Simon effect (fastest responding when tone location and direction of wheel turn corresponded) was obtained when participants' hands were at the top or middle of the wheel but not at the bottom. With the bottom hand placement, a Simon effect was induced by instructions emphasizing hand movements but not by instructions emphasizing wheel movements (Experiment 2), and by a visual cursor controlled by the wheel but not one triggered by the response (Experiment 3). The results of the experiments showed that the nature of the task and the instructed action goal influence the direction of the Simon effect.     

Is the interference between memory processing and timing specific to the use of verbal material?

Increasing load in a memory task performed simultaneously with a timing task shortens perceived time, an effect that has been observed previously with memory tasks using verbal material. The present experiments examine whether two similar memory tasks, one in which verbal material is used and another one in which nonverbal material is used, would produce similar interference effects on concurrent time reproduction. In Experiment 1, the number of nonverbal stimuli (pseudo‐random dot patterns) was manipulated in a memory task performed while a temporal interval to be reproduced was encoded. Reproductions shortened proportionally to the duration of memory processing executed during time estimation. Verbal stimuli (consonants) were used in Experiment 2 in otherwise identical experimental conditions. Effects observed in Experiment 2 were comparable to those obtained in Experiment 1. Taken together, these results support the notion that interference from memory tasks on concurrent time estimation is not determined by the specific type of material processed in memory, but instead by the duration of memory processing.     

Is the interference between memory processing and timing specific to the use of verbal material?

Increasing load in a memory task performed simultaneously with a timing task shortens perceived time, an effect that has been observed previously with memory tasks using verbal material. The present experiments examine whether two similar memory tasks, one in which verbal material is used and another one in which nonverbal material is used, would produce similar interference effects on concurrent time reproduction. In Experiment 1, the number of nonverbal stimuli (pseudo-random dot patterns) was manipulated in a memory task performed while a temporal interval to be reproduced was encoded. Reproductions shortened proportionally to the duration of memory processing executed during time estimation. Verbal stimuli (consonants) were used in Experiment 2 in otherwise identical experimental conditions. Effects observed in Experiment 2 were comparable to those obtained in Experiment 1. Taken together, these results support the notion that interference from memory tasks on concurrent time estimation is not determined by the specific type of material processed in memory, but instead by the duration of memory processing.