The experiments reported here illuminate current understanding of the factors influencing false recall. These experiments employ a procedure reported by Roediger and McDermott (1995), who demonstrated that reliable, predictable intrusions can be elicited in single trial free recall by presenting subjects with short lists of words (e.g., bed, rest, awake, tired, dream, etc.), all of which are associates of a critical nonpresented word (e.g., sleep); the critical nonpresented word is recalled and recognized as having occurred in the list. In Experiment 1, high levels of false recall were obtained, replicating Roediger and McDermott's (1995) results; in addition, although introduction of a short (30 s) filled delay resulted in forgetting of studied items, false recall was maintained over the delay. On a final free recall test occurring 2 days later, the probability of false recall was increased when an initial test had been taken on the first day, relative to a condition in which no initial test had occurred. In addition, the probability of false recall exceeded the probability of veridical recall on the final test. In Experiment 2, when multiple successive tests were taken, the probability that subjects would later claim to remember the critical nonpresented item (i.e., to recollect something specific about its presentation) was enhanced relative to a single test condition. Experiment 3 examined the persistence of this memory illusion by giving subjects multiple opportunities to hear the list (in a multitrial free recall procedure). Although the probability of free recall diminished across successive trials, robust levels of false recall were still obtained after 5 study-test trials. When subjects returned 1 day later, the probability of free recall was enhanced (relative to the last trial of Day 1), whereas the probability of veridical recall diminished across the delay. Overall, results demonstrate that illusory memories can be extremely robust, persisting across time and repeated retrieval attempts. In some cases, the probability of false recall exceeds the probability of veridical recall. Results converge upon the conclusion that the act of retrieval can play a critical role in determining false recall.

This study examined the relationship between consequence probabilities and decisions concerning self-protective behavior. The hypothesis put forth was that the probabilities associated with many common risks are at a level at which variations in probability have little influence on risk decisions. Subjects were presented with hypothetical risk situations in which consequence probability, consequence severity, and the costs of precautionary actions were explicitly stated and systematically manipulated. Decisions concerning the likelihood of taking a specific precautionary action in response to these risks were examined as a function of these three factors. The results revealed a "probability equivalence" effect, ranges of probabilities over which precautionary intent was essentially invariant, and that these ranges were highly dependent on consequence severity. In general, precautionary intent decreased as a function of decreasing consequence probability. However, for situations with low consequence severity, precautionary intent began to stabilize, trending towards an apparent minimum at low probability levels. Increasing consequence severity also had the effect of decreasing the "probability threshold", the probability level below which subjects were unlikely to take precautionary action. Increasing precautionary costs was also found to consistently depress willingness to take precautions. Precautionary intent was also examined as a function of several characteristics of the decision makers. Most scenarios revealed that levels of precautionary intent increased with age. In addition, in more than half of the scenarios, males were less inclined to take precautions than females. Analyses at the individual subject level revealed considerable variability in probability threshold and equivalence effects, indicating that the use of probabilities in risk decisions is highly dependent on the characteristics of the decision maker and the risk situation. Collectively the findings support the notion that probability information can influence decisions concerning precautionary intent, but that the probability equivalence effect may render consequence probability a poor discriminator when judgments are made concerning similar risks. The results suggest that the probability effects were products of subjects' informal cost-benefit analyses as opposed to a failure to perceive meaningful differences in the probabilities.

Auditorily presented information is processed on an on-line basis to the extent possible (Marslen-Wilson and Tyler, 1980). Using sentences where immediate, on-line processing was not possible, this study investigated whether such sentences created a greater short-term memory burden for subjects. The types of sentences in which immediate integration was not possible had either a list of adjectives preceding a noun or a list of nouns preceding a verb. These were compared with sentences which had lists of adjectives following the noun or lists of nouns following the verbs, allowing for immediate integration. Two experiments, one using word detection and the other using a sentence anomaly judgment found support for the hypothesis that the inability to immediately integrate word meanings increases memory burden and impairs comprehension. However, the effects of the memory burden did not correlate with standard measures of short-term memory.

This dissertation reports the results of two experiments that examined potential explanations for the underestimation of project completion time. Experiment 1 examined whether estimators pay attention to important task characteristics when they estimate project completion time. Surprisingly, the majority of the sample ignored the intercommunication among group members required by the task when they estimated project completion time. No expert-novice differences were found. These results show a serious deficiency in subjects' awareness of the effect of this task characteristic on project completion time. Experiment 2 examined whether people underestimate project completion time because they misaggregate probabilistic time estimates for project components. Indeed, this experiment found that people use heuristics to combine probability distributions for serial and parallel tasks. These heuristics cause people to underestimate project completion time. However, the magnitude of these errors was small, compared to that of Experiment 1. These results suggest that although the misaggregation of time estimates may contribute to the underestimation of project completion time, it is probably not a primary cause of this bias. In conclusion, the primary explanation for the underestimation of project completion time appears to be that estimators of project completion time ignore important task characteristics that affect project completion time. To our knowledge, these studies are the first experimental examinations of cognitive biases in the estimation of project completion time. Conclusions that can be drawn from these studies provide interesting hypotheses for future research.

Discrete models of speaking maintain that semantic-syntactic and phonological representations are largely independent, whereas interactive accounts allow for mutual influence between them. The studies presented here investigated this issue by employing a task in which participants named pictures while instructed to ignore visually or auditorily presented distractor words. Previous results using this paradigm with auditory distractors have been used to support the discrete view (e.g., Schriefers, Meyer, & Levelt, 1991) whereas results with visual distractors have been used to argue for an interactive account (e.g., Starreveld & La Heilj, 1996a). The first two experiments served to clarify the discrepancy across distractor modalities. Experiment 1 demonstrated that with auditorily presented distractors semantic effects preceded phonological effects whereas with visual distractors phonological effects had an earlier onset than semantic effects. Experiment 2 provided a means for accounting for this discrepancy by demonstrating that the results for visual distractors followed the auditory pattern when presentation time was limited. The following two experiments addressed the issue of interactivity vs. modularity in speaking by employing auditory distractors and investigating the effects of complex types of distractors. Experiment 3 factorially crossed the factors of semantic and phonological relatedness by employing both semantically and phonologically related distractors (FLY-FLEA). An interaction between the two factors was obtained which was interpreted as supporting an interactive account of speaking. Experiment 4 investigated the effects of mediated distractors which are related to the picture name via an intervening word (TIDE-(TIGER)-LION). A potential effect of such distractors would require an interplay between semantic and phonological levels and thus further support an interactive view. The results showed no effects on naming latencies, a finding that probably is not diagnostic with regard to the question of interactive vs. modular accounts. The second part of this thesis introduced an interactive computational model closely related to Dell's (1986) model of speech production. This model yielded a sequence of semantic and phonological effects and showed an interaction between the two factors as well as the absence of mediated effects. In summary, the experiments and the model favor an interactive view of speaking in which semantic and phonological levels are closely interconnected.

Five experiments investigated whether phonological representations play a role in verbatim sentence repetition. Experiments 1 and 2 revealed that words related both semantically and phonologically to sentence words were more likely to be intruded into sentences than were words related only semantically. Experiment 4, the most stringently controlled, also yielded more intrusions for semantically and phonologically related lures, with a larger effect for abstract than concrete stimuli. Experiment 5 demonstrated that words related only phonologically to sentence words could be intruded into sentences as well. It is argued that veridical sentence recall taps phonological as well as semantic memory representations for accurate performance; a view inconsistent with the "Semantic Regeneration Hypothesis" offered by Potter and Lombardi (1990). Further, it is argued that the semantic and phonological representations act in an interactive fashion and support each other during sentence recall.

Brunswik's lens model (1955, 1956) was used in two experiments to provide feedback to subjects to use in improving baseball team win predictions. The lens model decomposes judgment into three component parts which were used as feedback; cue-criterion relationships (task information, TI), subject cue-utilization relationships (cognitive information, CI), and the relations between the criterion and subject predictions (functional validity information, FVI). In experiment 1, subjects given TI + CI or TI + CI + FVI improved their predictions to a greater extent than subjects given TI. It was also shown that subjects' prediction performance in the TI condition was moderated by domain knowledge. In experiment 2, subjects were unable to improve their performance in any of the lens model feedback conditions (TI, TI + CI, and modified CI). The type of domain knowledge termed "task knowledge" was found to be the most important predictor of performance.

In two experiments, subjects heard simple action statements (e.g., "break the toothpick") and, in some conditions, performed the action or imagined performing it. After 10 minutes, 24 hours, 1 week, or 2 weeks they imagined performing each action 0, 1, 3, or 5 times, where some actions had been previously heard and others had not. A later test showed that as the number of interpolated imaginings increased, overall recognition accuracy decreased in all conditions except when subjects imagined the events immediately before the test. Source monitoring was not systematically affected by the number of imaginings. However, imagination inflation was observed: As the number of imaginings increased, subjects increased their judgments that they had actually performed an event on the first occasion when they had not. Imagining events multiple times enhanced the hit rate for actions, and also increased subjects' claims that events had occurred when in fact they had not.

Gambling paradigms tapping both reward processing and decision-making tasks in control and patient populations have found differences in behavior based on individual differences in immediate reward representation. The current investigation examined decision-making in individuals who differed on self-reported measures of impulsivity and used event-related potentials (ERPs) to examine the network dynamics of reward and decision-making circuitry among low and high impulsive participants. An inferior frontal component, the anterior P2 (P2a), indexing orbitofrontal cortex (OFC) activity, and a medial frontal negativity (MFN), indexing anterior cingulate cortex (ACC) activity, were measured related to choices made from high-risk and low-risk decks of cards in two modified versions of the Iowa Gambling Task. Results indicated that the P2a indexed reward expectation in a single-presentation version of the Iowa Gambling Task and the MFN indexed evaluation of decisions in a dual-presentation version of the Iowa Gambling Task.

Evidence from brain-damaged patients suggests that there are separate buffers for input and output phonological retention in verbal short-term memory (STM). This possible distinction was investigated with college students (Experiment 1 to 3) and deaf signers of American Sign Language (ASL) (Experiment 4) using different verbal materials in a serial probed recall paradigm. It is reasoned that natural linguistic input (speech for hearing people and ASL for deaf people) would be stored in an input phonological buffer whereas internally generated phonology derived from reading, naming pictured objects, or lip-reading would be stored in an output phonological buffer. In this study, participants were presented with memory lists in which presentation modality (spoken vs. lip-read word, written vs. lip-read word, etc.) was changed after every second item. A probe item from the list was repeated at the end of the list and participants were instructed to either recall the item in the list that has immediately followed the probe or recall the first item after the probe that is in the same modality. Some of these same-modality items were temporally distant, that is, having two intervening items of a different modality. It is predicted that the temporally distant probe in the same modality with the target results in higher memory performance than the temporally adjacent probe in a different modality only if the switch in modalities is between input and output phonological forms. The results from Experiment 1 demonstrated that spoken words and written words were stored in the input and output phonological buffers, respectively. The results from Experiment 2 and 3 further supported the hypothesis in showing that written words were retained in the same buffer with lip-read words and with nameable pictures, while spoken words were retained in a different buffer from these materials. The findings from lists consisting of words in ASL and nameable pictures in Experiment 4 were not conclusive. However, preliminary data suggested that there might also be a separation between signed words and nameable pictures. Overall, the findings from this study conformed to the predictions from the hypothesis of separate input and output phonological retention.