Three experiments investigated the influence and timing of various goal- and stimulus-driven factors on the guidance of eye movements in a simple visual search task. Participants were asked to detect the presence of an object of a given color from among various distractor objects that could share either the color or shape of the target object. The contrast of one or more objects was manipulated to investigate the influence of an irrelevant salience cue on the eye movements. A time dependant analysis showed that participants' early eye movements were generally directed towards the upper left object in the display. The analysis further indicated that color then quickly became the primary guiding factor for the eye movements with salience and shape having minimal effects in early processing. Further analyses indicated that shape also influenced eye movement behavior, but largely to cancel eye movements to the target object and to end the trial without an eye movement. These analyses also indicated that shape was only processed when an object was attended because it had the target color. A model was developed and fit to the data of Experiment 1.

No description available.

Decision making in an uncertain environment is a formidable task. Input cues are weighted according to a decision rule and applied to an event to produce a judgment. Research into the quality of such decisions has provided mixed evidence. Psychology research suggests that decision makers employ heuristics (simplifying strategies) in arriving at judgments, and that their use may result in biased judgments. Such biases include underweighting of disconfirming information, insufficient adjustment from an initial anchor, overestimation of conjunctive probabilities, and neglect of base rates. However, these psychology studies typically examined the judgments of student subjects performing relatively unfamiliar, generic tasks. Some researchers question whether these observed biases may have resulted from an experimental mismatch between tasks and subjects. In particular, Edwards (1983) argued that different patterns of heuristic use might be evident when experienced decision makers perform familiar tasks. Also, Klayman and Ha (1987) suggest that decision makers may make use of specialized, "task-specific" heuristics in familiar contexts. Smith and Kida (1991)'s review of audit research on heuristics and biases indicates that the presence and extent of the aforementioned biases are often mitigated or modified when auditors perform familiar, job-related tasks. The central hypothesis of this study was that experience differences would affect auditors' heuristic use in audit tasks, but not in relatively unfamiliar, generic tasks. Results of the confirmatory decision strategy and anchoring and adjustment experiments supported this hypothesis. Although both experienced and inexperienced auditors' audit task judgments indicated the use of conservatism (preferential attention to negative information), inexperienced auditors' judgments were more negative than those of experienced auditors. There were no significant experience-related differences in either of these settings' generic tasks. The conjunctive probability judgment experiment also provided evidence of task-specific heuristic use, as experienced auditors produced significantly greater conjunction effects in the audit task than in the corresponding generic task. Overall, results provided some evidence suggesting that decision makers' heuristic use is affected by both individual and task differences. Additional research examining the effects of these differences on heuristic use should provide further insight into the strategies decision makers use in making judgments under uncertainty.

In a set of 7 experiments, the author examined if cue-competition effects such as blocking and overshadowing reflect deficits in learning (e.g., Rescorla & Wagner, 1972) or deficits in performance (Miller & Schachtman, 1985). To this end, the author tested if the ability of a blocked and/or overshadowed stimulus was weakened in its ability to serve as a blocker or second-order reinforcer for a novel stimulus. It was assumed that the ability of a stimulus to serve as a blocker or second-order reinforcer depended on its associative status, and not on the performance it evoked. CS-evoked suppression of appetitively-motivated barpressing served as the dependent measure of conditioned performance. Experiment 1 found that an overshadowed CS was weakened in its ability to serve as a blocker. Experiment 2 replicated Experiment 1 and further showed that a blocked stimulus was also weakened in its ability to serve as a blocker. Experiment 3 showed that a blocked and overshadowed stimulus was weakened in its ability to serve as a second-order reinforcer. The results of Experiments 1, 2, and 3 were construed as supporting a learning-deficit as opposed to a performance-deficit interpretation of cue-competition effects. Performance-deficit theorists, however, might claim that the weakened ability of a blocked and/or overshadowed CS to serve as a blocker or second-order reinforcer was due to the presence of an intact A-US association (the association produced by the blocking and/or overshadowing CS). Experiments 4 to 7 addressed this issue, using various techniques, which might weaken the allegedly interfering A-US association. Experiments 4 and 5 showed that extinguishing the blocking and/or overshadowing stimulus did not facilitate performance to and blocking ability of a blocked and/or overshadowed stimulus (Experiment 4) or overshadowed stimulus (Experiment 5). Experiment 6 further showed that subjecting the blocking and/or overshadowing cue to a Pavlovian conditioned inhibition procedure also did not enhance performance to the blocked and/or overshadowed stimulus. Finally, Experiment 7 showed that extinguishing the overshadowing stimulus weakened performance to the overshadowed stimulus. Collectively, the results of Experiments 1 to 7 are consistent with learning-deficit interpretations of cue-competition effects (e.g., Rescorla & Wagner, 1972; Mackintosh, 1975).

Three experiments investigated whether morphological constituents influence word processing during reading. Individuals read sentences containing free stem, bound stem, and pseudo-prefixed words. In Experiments 1 and 2, a parafoveal display change manipulation indicated that the morphological constituents of a prefixed word are not available for preprocessing in the parafovea as reading times on the target word did not differ for prefixed versus pseudo-prefixed words. Interestingly, parafoveal preview of word initial and word final letters resulted in an equivalent amount orthographic facilitation for all word types. In Experiment 3, a fast priming manipulation indicated that morphological priming effects for prefixed words are obscured during sentence processing. However, the form of the prime did facilitate subsequent word processing for all three word types. The results suggest that English prefixed words are accessed via their whole word form, as there was no evidence of morphological decomposition for prefixed words during sentence processing.

This dissertation investigates the ways in which speech perception is guided by the expectation that the stimulus is an utterance in the perceiver's language, with a particular focus on how phonotactics affects the interpretation of acoustically ambiguous segments. A model is proposed in which phonological grammar, expressed here as a system of ranked and violable constraints within the framework of phonological Optimality Theory, is used to select among competing candidate parses of the acoustic input. This grammar-based theory is contrasted with two grammarless alternative accounts of perception: the connectionist network TRACE, which derives phonotactic perceptual effects from the lexicon, and a statistical theory based on transitional probabilities. Experimental evidence is presented to show (1) that English listeners' judgments of vowels and of consonant clusters disfavor configurations which are grammatically illegal in the language, (2) that the dispreference for illegal configurations is far stronger than that for configurations which are legal but have zero frequency, and (3) that it is due to a response dependency, rather than to auditory or other stimulus factors, and cannot be explained by foreign-language exposure. Two experiments with Japanese listeners find that (1) the lexical stratum membership of nonsense words can produce a phonotactic perceptual effect, (2) that the triggering and target segments can be up to three segments distant, and (3) that the stratum-phonotactic effect is larger than a word-superiority effect obtained with the same listeners and paradigm. These results are shown to be consistent with the grammar-based model, but inconsistent with the two grammarless alternatives. Analysis of the three models reveals that the shortcomings of the alternatives is due to their inability to abstract over phoneme classes and larger linguistic structures. It is concluded that the mechanisms of speech perception have access to a full-fledged phonological competence.

This work presents an investigation of how prosodic information is used in natural language processing and how prosody should be incorporated into models of sentence comprehension. It is argued that the processing system builds a prosodic representation in the early stages of processing, and is guided by this prosodic representation through multiple stages of analysis. Specifically, the results of four sentence comprehension experiments demonstrate that prosodic phrasing influences syntactic attachment decisions, focus interpretation, and the availability of contextual information in the resolution of lexical ambiguity. Two explicit hypotheses of how prosodic structure is used in processing are proposed to account for these effects: one which accounts for effects of phonological phrasing on syntactic processing decisions and a second which accounts for effects of intonational phrasing on semantic/pragmatic interpretation. Three sources of evidence are provided in support of the central claim that the processor must build and use a prosodic representation from the early stages of processing. First, an experiment on the resolution of prepositional phrase attachment ambiguity demonstrates that syntactic attachment decisions are influenced by the overall pattern of phonological phrasing in utterance, and not simply by prosodic boundaries located at the point of syntactic ambiguity. Thus, the effects of a single kind of prosodic element, at a single level in the prosodic hierarchy, must be accounted for with respect to the larger prosodic structure. A second experiment shows that the interpretation of focus is dependent on both the pattern of pitch accents in the utterance and the pattern of prosodic phrasing, establishing that different kinds of prosodic elements in the prosodic structure are used jointly in processing decisions. Two additional experiments, one on the interpretation of context-sensitive adjectives and a second on the resolution of within-category lexical ambiguity, demonstrate that phonologically distinct levels of prosodic phrasing have separable effects on language processing. Taken together, the four experiments suggest that prosody has a much broader role in sentence comprehension than previously recognized, and that models of sentence processing should be modified to incorporate prosodic structure.

No description available.

The Stanford Prison Experiment (SPE) was conducted to determine the psychological and behavioural effects of adopting the roles of prisoners or prison guards. In various published research articles Zimbardo reported that he instructed the prison guards to maintain law and order (Haney, Banks, & Zimbardo, 1973). However, in the Quiet Rage video (Zimbardo, 1989), Zimbardo gave the prison guards additional detailed instructions. To examine the effects of these different instructions on expected prison guard role behaviour, first year Psychology students were requested to predict expected prison guard role behaviour under two different conditions. In the order condition, participants received the instructions used in published research articles. While in the fear condition, participants received the instructions from the Quiet Rage video (Zimbardo, 1989). Participants estimated the likelihood of 50 guard behaviours. Participants in the order condition predicted more pleasant behaviour, while participants in the fear condition predicted more unpleasant behaviours. This indicates that the different instructions influenced their intent to perform the different behaviours. There was no significant difference between the fear and order conditions, and the control behaviours. Participants in both the fear and order conditions rated the control items as expected prison guard role behaviour. Participants in both conditions indicated that they would behave in this manner. Gender had no significant influence on expected prison guard role behavior.

The positioning component of the human arm has four kinematic degrees of freedom (DOF), three of which are used to position the end-effector. The fourth DOF, here denoted $\gamma,$ does not affect the hand position (it exclusively affects the elbow position) and may thus be considered redundant. It may be hypothesized that, in the absence of any other constraints, $\gamma$ is chosen such that some task related cost is minimized. In this work, we investigate the particular hypothesis that $\gamma$ is chosen such that the sum of the squared torques at the shoulder and elbow is minimal. A particular feature of this minimum principle is that it associates costs with both movement and static posture. This feature distinguishes the minimum-torque principle from zero-static-cost (ZSC) principles such as the well-known minimum-jerk (Flash and Hogan, 1985) and minimum-torque-change (Uno, Kawato, & Suzuki, 1989) principles. The main objectives of this work are to (1) reject the validity of ZSC principles and (2) to expose the predictions that arise from the minimum-torque principle and to compare these predictions with observed behavior. Human performance is assessed in tasks which consist of the following three components: (1) A movement that places the end-effector in a specified position, (2) a period of posture maintenance of specified duration, and (3) a movement that returns the arm to its initial position. Only one dependent variable is considered: the $\gamma$ associated with the static posture adopted during the posture maintenance period. Performances from three experiments are analyzed. The results of the first experiment disconfirm the validity of ZSC principles, the results of the second experiment are ambiguous, and the results of the third experiment provide some evidence in support of the minimum-torque principle.