Arthur I. Schulman

Operating Characteristics, Signal Detectability, and the Method of Free Response

The method of free response refers to the following listening situation. Against a background of noise, a weak signal is presented several times in a long (2‐min) observation interval. The temporal intervals between the presentations of the tones are randomly distributed; consequently, the listener does not know when a tone will occur, and he does not know how many tones will be presented. From one series of observation intervals to the next, the listener is instructed to adopt various criteria and to press the single response‐key each time he “hears a tone.” The problem consists in the determination of a procedure that allows the total number of yes responses to be partitioned meaningfully between “hits” and “false alarms.” A model is developed in which the measurable quantity, rate of response, is related to the “hit rate” and to the “false‐alarm rate.” Although the criterion adopted by the listener cannot be directly evaluated, the use of a wide range of criteria makes it possible to estimate the detectability ds of the signal. Two experiments are described, and the results support the model.

Memory for words recently classified.

This paper describes research whose goal is to determine the implications of verba] classificatory, judgments for recognition memory and recall. Toward this end, St were required to answer 100 queries of attribution and superordination ds a TWINGE sudden? Is SPINACH ecstatic? Is a CORKSCREW an opener? Is a DUNGEON a scholar? before being tested unexpectedly on their ability to remember either the uppercase “keywords” or the lowercase “descriptors.” Lexical memory did not depend on whether a word had been part of an attributive or a superordinate query. But words from “incongruous” queries almost invariably were more poorly remembered-under conditions of free recall, cued recall, and recognition memory-than words from “congruous” queries. Congruous cues, but not incongruous ones, greatly facilitated recall, with keywords being more effective cues than descriptors. Recognition memory of keywords was uniformly superior to that of descriptors. It is argued that the large and pervasive memorial advantages of congruity arise because a congruous query, unlike an incongruous one, fosters a relational encoding of keyword and descriptor.

Interval of Time Uncertainty in Auditory Detection

Three experiments were conducted to measure the decrement in performance that results from uncertainty in the time of onset of a signal presented against a continuous background of noise. The fixed‐interval observation experiment was employed. A light defined an observation interval for the listener during which the signal, a tone of 1000 cps, either was or was not presented [p(SN)=0.5]. The signal, when presented, started at an instant randomly selected within the observation interval. Thus, the listener was uncertain as to (1) whether or not the signal would occur in the observation interval, and (2) the onset time of the signal, if in fact the signal occurred. The interval of time uncertainty (ITU) during which the tone might start was systematically varied from one series of trials to the next, and the listener knew the duration of ITU in each series. After each observation interval, the listener indicated his confidence that a tone was presented by using a rating scale. Operating characteristics [p(y...

Word length and rarity in recognition memory

Operating characteristics were used to assess the importance of word-frequency and word-length in recognition memory. It was much easier for Ss to distinguish between old and new rare words than between old and new common words. Rare (but not common) words were easier to recognize when they were polysyllabic than when they were not.

Recognition memory and the recall of spatial location

It is argued that memory for events should depend on the ability to recall their attributes. Two experiments suggest that this is so for the attribute of spatial location. When words presented in spatial arrays were later re-presented in a joint test of recognition memory and location recall, it was found that the surer one’s recognition, the greater the accuracy of location recall. Instructions to attend to a word’s location resulted in poorer recognition memory and marginally poorer location recall than were obtained when location was “incidentally” learned. Finally, when words were presented in color as well as in space, recognition memory was best when both attributes were recalled, was better when only location, was recalled than when only color was recalled, and was poorest when neither attribute was recalled.

The Declining course of recognition memory.

Recognition memory for words can decline, sometimes precipitously, over the course of the recognition test. Decrements of as much as 75% in d’ have been observed from the first quarter of testing to the last. and decrements of 40%–50% are not uncommon. Proactive mechanisms, imperfectly understood, appear to underlie such declines: Processing early input renders late input less recognizable, and making early recognition judgments renders later judgments more difficult. At the same time, the processing of late-input words fails to inhibit the recognition of the words that preceded them.

Operating characteristics and a priori probability of the signal

Two experiments in auditory signal detection produced changes in the operating characteristic as the a priori probability of signal occurrence, p(SN), was varied. The signal was a sinusoid of 1,000 Hz presented for 250 msec against a continuous background of noise. In Experiment 1 three values of p(SN)—0.25, 0.50, and 0.75—were paired with each of three signal intensities. In Experiment 2 the signal intensity was fixed and p(SN) was assigned values of 0.10, 0.25, 0.50, 0.75, and 0.90. On normal-normal coordinates, operating characteristics were fitted to the points obtained from the 4-point rating scale used by the listeners. Such operating characteristics may be specified by two parameters: ds, an index of detectability related to d’, and m, its slope. While ds was found to be independent ofp(SN), m was found to be a joint function of p(SN) and signal intensity. These results are discussed against the background of the theory of signal detectability.

Memory for Waveform and Time Uncertainty in Auditory Detection

An experiment was conducted to determine how well listeners could judge whether or not a signal was presented in a noisy observation interval which had already occurred. The cardinal feature of the experiment is that the observation interval is not marked off for the listeners until some fixed time after its occurrence. The listening situation is described as follows. With a probability of 0.5, the signal (1000 cps, 0.25 sec) is presented at a randomly selected instant. A fixed time thereafter, the listener is informed (by a flash of light) of the real time at which the sinusoid may have occurred, and he responds with a rating of confidence. As compared with the typical fixed‐interval experiment in auditory detection, two sources of uncertainty are emphasized in this situation: (1) The listener has a faulty memory of his transformation of the input waveform, and (2) he has a faulty estimation of the time of onset of the signal. From the results of previous experiments on the role of time uncertainty in de...

Recognition memory for words presented at a slow or rapid rate.

Fast presentation (about 1 word/sec) impairs subsequent recognition of both common and very rare words. This presentation rate, slow enough for accurate perception but probably too fast for much more elaborate information processing, also sharply reduces the variability of recognition memory scores.

Maps and Memorability

Things appear to us with a spatiality, a “whereness”, that we cannot ignore. Events, though they unfold over time, are said to take place. Not only do we realise that “everything is somewhere” (Robinson and Petchenik, 1976), but we record the spatiality of experience for future use. Some suggest we do this automatically or inevitably (cf Hasher and Zacks, 1979; Mandler, Seegmiller and Day, 1977); indeed, I have suggested as much (Schulman, 1973). But even if we must learn to observe and record spatiality, and even if our spatial records are incomplete or flawed, there can be no question of the existence of an “awareness of whereness” - an awareness whose implications for cognition it is my purpose here to explore.