Publications by authors named "Walter T Herbranson"

The secretary problem is a notorious mathematical puzzle in which one attempts to hire the best available candidate from a pool of known size. Under specific constraints, the problem has an ideal solution, but it is difficult for humans to solve. In particular, humans generally consider too few options from the available pool and in doing so make inferior hires.

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Change blindness is a phenomenon of visual attention, whereby changes to a visual display go unnoticed under certain specific circumstances. While many laboratory procedures have been developed that produce change blindness in humans, the flicker paradigm has emerged as a particularly effective method. In the flicker paradigm, two visual displays are presented in alternation with one another.

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Change blindness is a phenomenon whereby changes to a stimulus are more likely go unnoticed under certain circumstances. Pigeons learned a change detection task, in which they observed sequential stimulus displays consisting of individual colors back-projected onto three response keys. The color of one response key changed during each sequence and pecks to the key that displayed the change were reinforced.

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Change blindness is a phenomenon in which even obvious changes in a visual scene may go unnoticed. Recent research has indicated that this phenomenon may not be exclusive to humans. Two experiments investigated change blindness in pigeons, using a variant of the widely-used flicker task to investigate the influence of display timing on change blindness.

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Change blindness is a well-established phenomenon in humans, in which plainly visible changes in the environment go unnoticed. Recently a parallel change blindness phenomenon has been demonstrated in pigeons. The reported experiment follows up on this finding by investigating whether change salience affects change blindness in pigeons the same way it affects change blindness in humans.

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The Monty Hall dilemma is a probability puzzle in which a player tries to guess which of three doors conceals a desirable prize. After an initial selection, one of the nonchosen doors is opened, revealing that it is not a winner, and the player is given the choice of staying with the initial selection or switching to the other remaining door. Pigeons and humans were tested on two variants of the Monty Hall dilemma, in which one of the three doors had either a higher or a lower chance of containing the prize than did the other two options.

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Change blindness is a phenomenon in which even obvious details in a visual scene change without being noticed. Although change blindness has been studied extensively in humans, we do not yet know if it is a phenomenon that also occurs in other animals. Thus, investigation of change blindness in a nonhuman species may prove to be valuable by beginning to provide some insight into its ultimate causes.

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Experimental tasks designed to involve procedural memory are often rigid and unchanging, despite many reasons to expect that implicit learning processes can be flexible and support considerable variability. A version of the serial response time (SRT) task was developed, in which the locations of targets were probabilistically determined. Targets appeared in locations according to both a structured sequence and a cue validity parameter, and the time to respond to each target was measured.

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The "Monty Hall Dilemma" (MHD) is a well known probability puzzle in which a player tries to guess which of three doors conceals a desirable prize. After an initial choice is made, one of the remaining doors is opened, revealing no prize. The player is then given the option of staying with their initial guess or switching to the other unopened door.

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In two experiments, we developed a new methodology for studying complex stimulus control by spatial sequences of letters generated by artificial grammars. An artificial grammar is a system of rules that defines which letter sequences or strings are "grammatical." In Experiment 1, pigeons learned to respond differently to strings conforming to a grammar versus strings that were nongrammatical distortions.

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An avian analogue to human artificial or synthetic grammar learning (Reber, 1967) was developed. Pigeons viewed horizontal strings of three to eight colored letters. These strings either conformed to Reber's artificial grammar or violated it in one or two locations.

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Pigeons categorized a moving target in terms of its speed and direction in an adaptation of the randomization procedure used to study human categorization behavior (Ashby & Maddox, 1998). The target moved according to vectors that were sampled with equal probabilities from two slightly overlapping bivariate normal distributions with the dimensions of speed and direction. On the average, pigeons categorized optimally in that they attended to either speed or direction alone, or divided attention between them, as was required by different reinforcement contingencies.

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It has previously been shown that pigeons can shift attention between parts and wholes of complex stimuli composed of larger, "global" characters constructed from smaller, "local" characters. The base-rate procedure used biased target level within any condition at either the local or global level; targets were more likely at one level than at the other. Biasing of target level in this manner demonstrated shifts of local/global attention over a time span consisting of several days with a fixed base rate.

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