Response assignment influences visual recognition.

This study investigated whether two different neural systems influenced performance in an immediate visual recognition, i.e. visual same/different task. An observer had to respond rapidly whether a test consonant had just appeared in the study string by pressing one of two response keys, labeled same and different. When the same response was assigned to the response key on the right, there was no effect of study-string position on target response time (RT), indicating that the test item was not compared with the study string. When the different response was assigned to the response key on the right, same RT was an increasing function of the left-to-right position of a target in the study string and different RT was slower than same RT, indicating that during test the study string was compared with the test item. Functional magnetic resonance imaging confirmed that the caudate and left hippocampus were more active when the different response was assigned to the right key but the right hippocampus was more active when the same response was assigned to the right key. Therefore, two different computational processes are performed by two different brain systems depending on whether the same or different response is assigned to the right response key.

Within the framework of the dual-system model, voluntary action is central to cognition.

A new version of the dual-system hypothesis is described. Consistent with earlier models, the improvisational subsystem of the instrumental system, which includes the occipital cortex, inferior temporal cortex, and medial temporal cortex, especially the hippocampus, directs the construction of visual representations of the world and constructs ad-hoc responses to novel targets. The habit system, which includes the occipital cortex; parietal cortex; premotor, supplementary motor, and ventrolateral areas of frontal cortex; and the basal ganglia, especially the caudate nucleus, encodes sequences of actions and generates previously successful actions to familiar targets. However, unlike in previous dual-system models, human cognitive activity involved in task performance is not exclusively associated with one system or the other. Rather, the two systems make it possible for people to learn a variety of skills that draw on the competencies of both systems. The collective effects of these skills define human cognition. So, in contrast with earlier versions of the dual-system hypothesis, which identified the habit system solely with procedural learning and implicit improvements in task performance, the model presented here attributes a direct role in declarative-memory tasks to the habit system. Furthermore, within the model, the computational competencies of the two systems are used to construct purposeful sequences of actions-that is, skills. Human cognition is the result of the performance of these skills. Thus, voluntary action is central to human cognition.

Classroom instruction results in better exam performance than online instruction in a hybrid course.

The purpose of this experiment was to determine whether performance on a subsequent exam was affected when two lessons were as similar as possible except that one was presented in class and the other was presented online. In a hybrid course, half of the lessons were presented in the classroom as narrated Power Point presentations and half of the lessons were presented online as narrated Power Point presentations. Online student-teacher interaction took place in a chatroom. Furthermore, for each question on the midterm or final examination, the students had answered a pre-lesson and post-lesson question, integrated with the appropriate lesson, which queried the same fact statement as the exam question. Students performed better on post-lesson questions asked in class than post-lesson questions asked online. They also performed better on exam questions on classroom lessons than exam questions on online lessons. The results support the conclusion that social interaction aids learning.

Dissociating Medial Temporal and Striatal Memory Systems With a Same/Different Matching Task: Evidence for Two Neural Systems in Human Recognition.

The medial temporal lobe and striatum have both been implicated as brain substrates of memory and learning. Here, we show dissociation between these two memory systems using a same/different matching task, in which subjects judged whether four-letter strings were the same or different. Different RT was determined by the left-to-right location of the first letter different between the study and test string, consistent with a left-to-right comparison of the study and test strings, terminating when a difference was found. This comparison process results in same responses being slower than different responses. Nevertheless, same responses were faster than different responses. Same responses were associated with hippocampus activation. Different responses were associated with both caudate and hippocampus activation. These findings are consistent with the dual-system hypothesis of mammalian memory and extend the model to human visual recognition.

Delayed, but not immediate, feedback after multiple-choice questions increases performance on a subsequent short-answer, but not multiple-choice, exam: evidence for the dual-process theory of memory.

Three experiments, two performed in the laboratory and one embedded in a college psychology lecture course, investigated the effects of immediate versus delayed feedback following a multiple-choice exam on subsequent short answer and multiple-choice exams. Performance on the subsequent multiple-choice exam was not affected by the timing of the feedback on the prior exam; however, performance on the subsequent short answer exam was better following delayed than following immediate feedback. This was true regardless of the order in which immediate versus delayed feedback was given. Furthermore, delayed feedback only had a greater effect than immediate feedback on subsequent short answer performance following correct, confident responses on the prior exam. These results indicate that delayed feedback cues a student's prior response and increases subsequent recollection of that response. The practical implication is that delayed feedback is better than immediate feedback during academic testing.

The effect of a final exam on long-term retention.

Testing on a final exam in a college course improved long-term retention over material that had not been tested on the final. Students from an upper level psychology course took a long-term retention test, four to five months after the end of the course. For half of the items, a related question had been on the final. For the remaining half, a related question had appeared on an earlier exam, but not the final. On the long-term retention test, percent correct was 79% when a related question had appeared on the final and 67% when a related question had not appeared on the final. These results have both theoretical and practical implications.

Visual identity and uncertainty in repetition blindness.

Repetition blindness (RB) was investigated in 6 experiments. In the first 3 experiments participants detected vowel targets in 11-letter sequences. When all letters were uppercase, detection was poorer for same (e.g., AA) than for different (e.g., AO) targets. However, when one target was uppercase and the other lowercase, RB was found only for targets visually identical except for size (e.g., Oo), not for visually different pairs (e.g., Aa). Experiment 4 found RB for visually identical versus different consonant-vowel-consonant words. Experiments 5 and 6 replicated Kanwisher's (1987) experiment in which RB was insensitive to word case but revealed these effects to be artifacts of poor recognition of 5-letter words coupled with a biased guessing strategy. Overall, these experiments found RB only at a low level of visual information processing.

Neurogenesis and the spacing effect: learning over time enhances memory and the survival of new neurons.

Information that is spaced over time is better remembered than the same amount of information massed together. This phenomenon, known as the spacing effect, was explored with respect to its effect on learning and neurogenesis in the adult dentate gyrus of the hippocampal formation. Because the cells are generated over time and because learning enhances their survival, we hypothesized that training with spaced trials would rescue more new neurons from death than the same number of massed trials. In the first experiment, animals trained with spaced trials in the Morris water maze outperformed animals trained with massed trials, but there was not a direct effect of trial spacing on cell survival. Rather, animals that learned well retained more cells than animals that did not learn or learned poorly. Moreover, performance during acquisition correlated with the number of cells remaining in the dentate gyrus after training. In the second experiment, the time between blocks of trials was increased. Consequently, animals trained with spaced trials performed as well as those trained with massed, but remembered the location better two weeks later. The strength of that memory correlated with the number of new cells remaining in the hippocampus. Together, these data indicate that learning, and not mere exposure to training, enhances the survival of cells that are generated 1 wk before training. They also indicate that learning over an extended period of time induces a more persistent memory, which then relates to the number of cells that reside in the hippocampus.

Retrieval independence between parts and wholes in successive recognition tasks.

Participants studied AB word pairs and completed three recognition tests. In one recognition test each A word was presented with two distractors that did not appear on the study list. In another recognition test each B word was presented with two distractors that did not appear on the study list. In a third recognition test an AB target was presented with two distractors composed of words not on the study list. Six different groups of participants each performed the recognition tests in a different order, so that all possible orders were tested. Recognition of the A, B, and AB targets for a given study pair were independent of each other when single-word recognition preceded double-word recognition. There was almost complete independence in the reverse order. Even when recognition judgements were restricted to those for which the participants were most confident, there was independence of recognition among the three tests. A pair recognition test served as an additional study trial for the individual words; however, the reverse was not the case. All of these results were predicted by a single three-parameter mathematical model derived from the hypothesis that single-word and double-word targets had independent representations in memory.

Detection of repeated trigrams: evidence of all-or-none learning.

Two experiments investigated trigram detection in a continuous recognition task. In Experiment 1 consonant trigrams were presented visually, one at a time, with occasional repetition of a trigram after an interval of 0, 2, 4, 8, or 16 other trigrams. Subjects were told to respond with a button press every time they saw a repeated trigram. If a subject responded to a repeated trigram, it was not repeated again. However, if a subject did not respond to a repeated trigram, it was repeated again at the same interval for up to 3 repetitions. For all intervals greater than 0, the probability of noticing a repeated trigram did not increase with the number of repetitions. In Experiment 2 meaningless shape trigrams were presented, and occasionally a trigram was repeated after an interval of 0, 1, or 2 trigrams. For both intervals greater than 0, the probability of noticing a repeated trigram did not increase with the number of repetitions. The results demonstrate that a repeated input does not necessarily leave a permanent trace in memory.

Retrieval independence in successive recognition tasks.

In three experiments participants studied AB word pairs and completed two recognition tests. In the first recognition test, which was included in all three experiments, the B word had to be discriminated from two distractors that did not appear on the study list. In Experiment 1, in the second recognition test, an AB target was compared with distractors composed of words not on the study list. In Experiment 2, in the second recognition test, an AB target had to be discriminated from two other pairs that were created by randomly re-pairing A and B words that appeared on the study list. In Experiment 3, on the second recognition test, words from the study list were systematically re-paired to form distractors that contained either the same A term or the same B term as the target pair. Recognition of the B word on the first test was always at least partly independent of recognition of the AB pair on the second test. Even when recognition judgements were restricted to those for which the participants were most confident, all experiments demonstrated significant retrieval independence between the two tests.

Grammatical intuitions about irregular verb inflections.

If people possess a rule that the root of a verb plus -ed produces the past tense, why does this rule produce an unacceptable form when applied to an irregular verb (e.g., comed)? One possibility is that the unacceptability of comed is the result of lexical priming. That is, comed primes the correct form came, and the awareness of came causes comed to be perceived as unacceptable. If so, then the acceptability of a misinflected form should be determined by the factors that influence the priming of its correct form, such as the frequency and hence speed of retrieval of its correct form. Three experiments were conducted. In Experiment 1, subjects were faster to reject misinflected irregular verbs when the correct irregular form had a higher frequency than when it had a lower frequency. Furthermore, the higher the frequency of the correct form, the more unacceptable the misinflected form seemed. Experiment 2 used the naming task to confirm that the presentation of a misinflected form facilitated the naming of its correct form. In Experiment 3, subjects were faster to accept an irregular verb when it was primed by a misinflected irregular verb than with a correct regular verb. This was taken as evidence that the misinflected irregular verb accesses the correct form.