Hippocampus lesions impair landmark array spatial learning in homing pigeons: a laboratory study

Hippocampal (HF)-lesioned pigeons display impaired homing ability when flying over familiar terrain, where they are presumably relying on a map-like representation of familiar landmarks to navigate. However, research carried out in the field precludes a direct test of whether hippocampal lesions compromise the ability of homing pigeons to navigate by familiar landmarks. To examine more thoroughly the relationship between hippocampus and landmark spatial learning, control, neostriatum-lesioned, and HF-lesioned homing pigeons were trained on two open field, laboratory, conditional discrimination tasks. One was a visual landmark array task, and the other was a room color discrimination task. For the tasks, the correct of three differently colored food bowls was determined by the spatial relationship among a group of five landmarks and room color, respectively. Intact control birds successfully learned both tasks, while neostriatum-lesioned birds successfully learned the landmark array task-the only task on which they were trained. By contrast, HF-lesioned birds successfully learned the room color task but were unable to learn the landmark array task. The data support the hypothesis that homing performance deficits observed in the field following hippocampal lesions are in part a consequence of an impairment in the ability of lesioned pigeons to use familiar visual landmarks for navigation.     

Understanding photos,models, and beliefs: A test of the modularity thesis of theory of mind

Recent experimental findings suggest that there is a dissociation between the performance by children with autism on False Belief tasks, on which they do poorly, and False Photograph, False Maps, and False Drawing tasks, on which they do well. This may be because only the False Belief task taps the capacity for metarepresentation, at least as defined by Leslie and Thaiss (1992). In an attempt to test the modularity of this capacity further, the performance of participants with autism on DeLoache's (1987, 1991) Model and Photograph tasks (which test understanding of the symbolic function of models and photographs), and on a standard False Belief task, was compared to that of mental handicap controls. The majority of participants from both groups passed the Photograph and Model tasks, and on neither task were there group differences. However, participants with mental handicap were significantly more successful on the False Belief task than those with autism. These results provide further support for the modularity of theory of mind, and the specificity of the metarepresentational deficit in autism.     

Caudate nucleus and memory for egocentric localization

A large body of evidence suggests that the caudate nucleus (CN) plays a critical role in the processing of spatial localization information. Furthermore, evidence has begun to accumulate that the CN is involved in the processing of a very specific class of spatial cues, namely, egocentric cues (localization with reference to the organism). This is in contrast to allocentric localization, where an organism localizes on the basis of cues external to the organism. One would then predict that lesions to the CN should disrupt performance on any tasks that depend chiefly on egocentric spatial cues, while leaving performance on allocentric tasks intact. To test this prediction, two groups of rats were trained on two different egocentric memory tasks and two different allocentric memory tasks. Specifically, one group of rats was trained on an adjacent-arm (egocentric) and an 8-arm radial maze task (allocentric). A second group of rats was trained on a right-left discrimination (egocentric) and a place-learning task (allocentric). After training, both groups received bilateral lesions of the CN. Results showed that CN-lesioned animals were profoundly impaired on retention of the egocentric tasks. In sharp contrast to this, the same animals were not or were only transiently impaired or transiently affected on allocentric tasks. Sham-operated controls were either unimpaired or transiently affected on all tasks. These findings further support the idea that the CN plays a critical modulatory role in the processing of egocentric spatial and not allocentric spatial cues.     

Dissociation of implicit and explicit memory tests: Effect of age and divided attention on category exemplar generation and cued recall

In this article, we report an experiment that provides further evidence concerning the differences between explicit and implicit measures of memory. The effects of age and divided attention on the implicit conceptual test of category exemplar generation (CEG) were compared with their effects on the explicit test of cued recall, where the category names served as cues in both tasks. Four age groups (20–35, 40–55, 60–75, and 76–90) were compared. Half of the subjects were also required to carry out a secondary letter-detection task during the learning phase. Cued recall performance was significantly impaired by increased age and imposition of the secondary task. In contrast, the CEG task was unaffected by these two factors. These results suggest that implicit conceptual tasks and explicit memory tasks are mediated by different processes. This conclusion opposes those of previous studies that showed that experimental manipulations (level of processing, generation, organization) influenced these two kinds of memory tests in a similar way.     

Your words are my words: Effects of acting together on encoding

Social influences on action and memory are well established. However, it is unknown how acting together affects the incidental encoding of information. The present study asked whether coactors encode information that is relevant to a partner's task, but irrelevant to their own task. In Experiment 1, participants performed a categorization task alone and together, followed by a surprise free recall test where they were asked to recall items from the categorization task. Recall was better not only for items that participants had responded to themselves, but also for items that their coactor had responded to, than for items that had not required a response. The same results were found in Experiment 2, even though financial incentives motivated participants to only encode words they had responded to themselves. Together, the findings suggest that performing tasks together can modulate how information relevant to coactors is processed. Shared task representations may act as a vehicle for establishing shared memories.     

A reversed-reward contingency task reveals causal knowledge in chimpanzees (Pan troglodytes)

In the reversed-reward contingency task, subjects are required to choose the less preferred of two options in order to obtain the more preferred one. Usually, this task is used to measure inhibitory skills, but it could also be used to measure how strong the subjects’ preferences are. We presented chimpanzees with support tasks where only one of two paper strips could physically bring food into reach. Subjects were rewarded for choosing the non-functional strip. In Experiment 1, subjects failed to pick the non-baited strip. In Experiment 2, subjects failed to pick the broken strip. Chimpanzees performed worse in these tasks than in other similar tasks where instead of paper strips, there were similar shapes painted on a platform. The fact that subjects found the reversed-reward contingency task based on causality more difficult to solve than a perceptually similar task with no causality involved (i.e., arbitrary) suggests that they did not treat real strips as an arbitrary task. Instead, they must have had some causal knowledge of the support problem that made them prefer functional over non-functional strips despite the contrary reward regime.     

A general framework for the analysis of concept identification tasks

A general framework is presented for concept identification based on hypothesis-testing theory. It is a modification of the duoprocess theory presented by Chumbley (1972). It is shown how Markov models for various complex concept identification tasks may be derived from this framework and how such models may be analyzed by making use of probability generating functions. Two experiments are described. In experiment 1 three tasks were used: two simple tasks, where the subject either only had to select the relevant dimension in order to solve the problem or only had to learn a short list of paired-associates, and a more complex task, where both processes were needed to reach the solution. The results were in general favorable to the theory. Experiment 2 was designed to test the application of the theory to the four-choice concept problem. The predictions of the theory are compared to those of the subproblem learning theory of trabasso and Bower (1964), modified to include a ‘learning-on-errors’ assumption. The fit of the duoprocess theory was reasonably good and superior to that of the subproblem learning theory.     

Anticipatory and control processes in the interaction with secondary tasks while driving

The paper describes an experiment where anticipatory processes in the interaction with secondary tasks while driving could be explicitly identified and contrasted to control processes during the engagement in the secondary task. A special experimental set-up in a driving simulator environment was created that allows drivers to deliberately decide whether they want to be distracted or not depending on the driving situation and the expected development of that situation. As indicators for a situation-adaptive interaction with secondary tasks parameters from driving behaviour, secondary task performance and visual behaviour were analyzed. A study with 24 test drivers revealed that drivers are, in general, able to interact with a secondary task in a situation-aware manner. For example, drivers rejected more secondary tasks in already highly demanding situations or tried to delay the beginning of the task. During secondary task performance drivers observed the situational development with short control glances back to the road and adapted their speed. The analysis of driving errors revealed that rejecting a task in an already highly demanding driving situation is an effective strategy to maintain an adequate level of driving safety. However, some critical factors were identified that might hinder the driver from executing such strategies. Several recommendations for supporting the driver on this issue are given.     

The Short-Term Memory of Profoundly Deaf People for Words,Signs, and Abstract Spatial Stimuli

The short-term memory (STM) of 25 deaf and 20 hearing adults fluent in Australian Sign Language (Auslan) was tested using both free- and serial-recall versions of three tasks. On two tasks, where stimuli were presented as either written words or Auslan signs, hearing subjects performed significantly better than deaf subjects. This difference was attributed to the facility of the hearing subjects in translating these two classes of language-based stimuli into phonological codes, which have a preferred status in STM. On the third, language-free task, which was an adaptation of the Corsi Blocks test, the deaf and hearing subjects performed at comparable levels, indicating that differences in their STM became evident only with the introduction of language-based factors. Analyses restricted to the deaf subjects showed that performances on the language-based STM tasks correlated positively with scores on a reading comprehension test. Also, deaf subjects who reported an oral education outperformed their counterparts, who reported a total communication (oral plus signed English) education on the language-based STM tasks. Thus, for this diverse adult deaf sample, proficiency in STM for language-based material, skill in reading, and report of an oral rather than total communication education appear to covary.     

Preliminary identification of nonlinear correlations for spatial tests and reaction-time tasks

Scores on three spatial tests (mental rotation, embedded figures, and gestalt completion) were significantly correlated with four same-different reaction-time tasks in a sample of 48 female university students. Scores on the Vandenberg-Kuse mental rotation test correlated best with a one-different-all-different task, embedded figures with a one-different-all-same task, and the gestalt completion with a one-same-all-same task, suggesting that the strategies subjects employ for each spatial test are similar to the strategies they use in each of the same-different tasks with which their scores correlate best. Present results support the position that stronger correlations than previously noted between scores on spatial tests and reaction-time tasks are observed when matching the tests and tasks in terms of hypothesized underlying processes.     

Effects of fatigue induced by repetitive movements and isometric tasks on reaction time

PurposeThe understanding of fatigue of the human motor system is important in the fields of ergonomics, sport, rehabilitation and neurology. In order to understand the interactions between fatigue and reaction time, we evaluated the effects of two different fatiguing tasks on reaction time.Methods83 healthy subjects were included in a case-control study with three arms where single and double choice reaction time tasks were performed before and after 2 min fatiguing task (an isometric task, a finger tapping task and at rest).ResultsAfter an isometric task, the right-fatigued hand was slower in the choice component of a double choice reaction time task (calculated as the individual difference between single and double choice reaction times); also, the subjects that felt more fatigued had slower choice reaction time respect to the baseline assessment. Moreover, in relationship to the performance decay after two minutes, finger tapping task produces more intense fatigability perception.ConclusionsWe confirmed that two minutes of isometric or repetitive tasks are enough to produce fatigue. The fatigue perception is more intense for finger tapping tasks in relation to the performance decay. We therefore confirmed that the two fatiguing tasks produced two different kind of fatigue demonstrating that with a very simple protocol it is possible to test subjects or patients to quantify different form of fatigue.     

Separating item-related electrophysiological indices of retrieval effort and retrieval orientation

The relationship between two classes of retrieval process-retrieval orientation and retrieval effort-was investigated using electrophysiological (ERP) and behavioural measures. ERPs were recorded during retrieval phases of exclusion tasks in which participants focused on retrieval of either phonological or semantic associates that were generated in a prior study phase. Participants were separated into two groups on the basis of the relative accuracy of their memory judgments in the retrieval tasks (high vs. low relative difficulty) as a means of assessing retrieval effort. The critical contrasts were between the ERPs evoked by unstudied test items separated according to group and emphasis of the retrieval task (semantic vs. phonological). Reliable differences according to task were evident in the high relative difficulty group only. This finding is consistent with the view that, for this task pair at least, ERPs are sensitive to the processes set in train in pursuit of task relevant information (retrieval orientations) only when relative difficulty is high.     

Distinctiveness of processing,processing time and memory performance

The research reported here, explored the conditions where processing time can be used as a predictive measure for retention performance. The results showed that, in similar but quantitatively different tasks, both processing time and retention performance increased with increasing task difficulty. The strongly suggests that processing time can be used as an independent measure for extensiveness of processing, and as a predictor for later retention performance. This relationship, however, is restricted to the comparison of similar processing tasks that differ only in the amount of processing necessary to perform the task.It is hypothesized that longer processing times are indicative of more extensive processing, leading to the formation of more distinctive memory representations. These, in turn, cause higher retention performance because they allow better discrimination from other memory traces, and because they are retrieved more easily.Although distinctiveness of memory representations is an important variable in determining retention performance, it is not the only one. In a recall test, semantic relations between items had an effect on performance independent of distinctiveness.     

Sex differences in spatial task performance of patients with and without unilateral cerebral lesions

Two visuospatial tasks, the WAIS Block Design and the Street Gestalt Completion Test, were administered to men and women with and without unilateral cerebral lesions. These two tasks represent different categories of visuospatial functions. The Street test is a visual-perceptual gestalt task, requiring the closure of fragmented pictures, whereas Block Design is an analytical, manipulospatial task requiring rotation of spatial coordinates. For the non-brain-damaged group, the men showed a nonsignificant trend toward better Block Design performance relative to the women, whereas there was no sex-related difference in Street performance. For the brain-damaged groups, patients with right hemisphere lesions performed significantly worse than patients with left hemisphere lesions on both the Street test and Block Design, indicating that both tasks were more sensitive to right hemisphere functioning. There was, however, a significant sex X side of lesion interaction on Block Design only, with the men showing a more asymmetrical pattern of scores. These results suggest that sex differences in functional lateralization may underlie sex differences in visuospatial ability, and that sex differences in functional lateralization may be present for only certain visuospatial processes.     

An investigation of cognitive test performance across conditions of silence,background noise and music as a function of neuroticism

The present study investigates the role of trait neuroticism on cognitive performance under distraction. Seventy participants were given a personality test and then undertook a number of different cognitive tasks in silence, in the presence of popular music and in background noise. It was predicted that performance on a general intelligence test, a test of abstract reasoning, and a mental arithmetic task would be adversely affected by background sounds. It was predicted that neuroticism would be negatively correlated with performance on the mental arithmetic task but only when the individuals were working in the presence of background sound. Stable vs. unstable participant's performance on a mental arithmetic task during noise was significantly higher as predicted. The results provided partial support for the hypotheses and are discussed with respect to previous findings in the literature on personality (particularly introversion–extraversion) and distraction on cognitive task performance. Limitations are noted.     

Relationships between implicit and explicit uncertainty monitoring and mindreading: Evidence from autism spectrum disorder

We examined performance on implicit (non-verbal) and explicit (verbal) uncertainty-monitoring tasks among neurotypical participants and participants with autism, while also testing mindreading abilities in both groups. We found that: (i) performance of autistic participants was unimpaired on the implicit uncertainty-monitoring task, while being significantly impaired on the explicit task; (ii) performance on the explicit task was correlated with performance on mindreading tasks in both groups, whereas performance on the implicit uncertainty-monitoring task was not; and (iii) performance on implicit and explicit uncertainty-monitoring tasks was not correlated. The results support the view that (a) explicit uncertainty-monitoring draws on the same cognitive faculty as mindreading whereas (b) implicit uncertainty-monitoring only test first-order decision making. These findings support the theory that metacognition and mindreading are underpinned by the same meta-representational faculty/resources, and that the implicit uncertainty-monitoring tasks that are frequently used with non-human animals fail to demonstrate the presence of metacognitive abilities.     

Contextual Interference in Motor Learning: Dissociated Effects Due to the Nature of Task Variations

The contextual interference effect in motor learning refers to the interference that results from practising a task within the concept of other tasks in a practice session. Several studies have shown that practice under conditions of high contextual interference (i.e. with a random practice order) degrades performance during acquisition trials, compared to low contextual interference conditions (i.e. with a blocked order, where practice is completed on one task before practice on another task is undertaken). In contrast to acquisition performance, random practice usually leads to more effective learning than blocked practice, as measured by retention and transfer tests. One of the hypotheses regarding the effect suggests that a random practice schedule induces more extensive planning operations during practice than a blocked practice condition. If so, then differences between these two conditions should emerge to the degree that the set of tasks requires complete reconstruction of these planning operations on each trial. To address this issue, we compared four groups of subjects: a blocked and random group that practised three timing tasks that shared a common characteristic (same relative timing), and a blocked and random group that practised three tasks that each had different relative timing structures. Subjects practised these tasks on each of two days, with a retention test and two transfer tests that required either a relative timing structure that had been practised previously or had not previously been practised. No random/ blocked differences occurred regardless of the relative timing of the patterns during acquisition or retention. However, for both transfer tests, random practice enhanced learning only for the group that had practised with tasks that each had different relative timing during acquisition. Implications of these results for an explanation of contextual interference are discussed.     

Visuospatial skills and their association with math performance in girls with fragile X or Turner syndrome.

The present study was designed to assess object identification ("what") and location ("where") skills among girls with fragile X or Turner syndrome and girls with neither disorder. Participants completed standardized subtests of visual perception and tasks of visuospatial "what" and "where" memory. Girls with fragile X had average performance on most object identification tasks, yet 53% failed to accurately recreate the gestalt of a design during the "where" memory task. Fewer than 7% of girls in the Turner or comparison group made this error. Girls with Turner syndrome had lower scores and longer response times on object perception tasks and had poorer recall of location for internal features of the design on the "where" memory task, relative to girls in the comparison or fragile X group. When limiting analyses to IQ-matched samples, correlations between math and visual perception tasks emerged, but only for girls with fragile X. These results reflect important differences between two cognitive phenotypes and have implications for the role of visuospatial processing in early math performance.     

Secondary-task effects on sequence learning

With a repeated sequence of stimuli, performance in a serial reaction-time task improves more than with a random sequence. The difference has been taken as a measure of implicit sequence learning. Implicit sequence learning is impaired when a secondary task is added to the serial RT task. In the first experiment, secondary-task effects on different types of sequences were studied to test the hypothesis that the learning of unique sequences (where each sequence element has a unique relation to the following one) is not impaired by the secondary task, while the learning of ambiguous sequences is. The sequences were random up to a certain order of sequential dependencies, where they became deterministic. Contrary to the hypothesis, secondary-task effects on the learning of unique sequences were as strong or stronger than such effects on the learning of ambiguous sequences. In the second experiment a hybrid sequence (with unique as well as ambiguous transitions) was used with different secondary tasks. A visuo-spatial and a verbal memory task did not interfere with the learning of the sequence, but interference was observed with an auditory go/no-go task in which high- and low-pitched tones were presented after each manual response and a foot pedal had to be pressed in response to high-pitched tones. Thus, interference seems to be specific to certain secondary tasks and may be related to memory processes (but most likely not to visuo-spatial and verbal memory) or to the organization of sequences, consistent with previous suggestions.     

空间工作记忆负载对真实场景情境提示效应的影响

重复的画面布局能够促进观察者对目标项的搜索 (情境提示效应)。本研究采用双任务范式,分别在视觉搜索任务的学习阶段 (实验2a) 和测验阶段 (实验2b) 加入空间工作记忆任务, 并与单任务基线 (实验1)进行比较, 考察空间工作记忆负载对真实场景搜索中情境线索学习和情境提示效应表达的影响。结果发现: 空间负载会增大学习阶段的情境提示效应量, 同时削弱测验阶段的情境提示效应量, 而不影响情境线索的外显提取。由此可见, 真实场景中情境线索的学习和提示效应的表达均会受到有限的工作记忆资源的影响, 但情境线索提取的外显性不变。