Modality-specific interference with verbal and nonverbal stimulus information

Subjects recalled both letters and the locations of letters in 2 by 3 and 1 by 6 matrices after either no interfering activity or visual, auditory, or kinesthetic interfering activity. Results for each type of matrix indicated the presence of selective auditory (verbal) interference with the recall of letter identity and selective visual and kinesthetic interference with the recall of letter location. Supplementary correlational analyses indicated that the presence of such a dual encoding strategy was most consistent across subjects for the 2 by 3 matrix. Although the results indicated that use of different modes of representation was related to the verbal-nonverbal nature of the information, it was shown that the structure of the stimulus array also affected the nature of the representation.     

Latency of different verbal responses to the same stimulus

A response of reading (letter O) or of naming (circle) can be given to the same sign O. The verbal reaction time is higher when naming than when reading (difference 100 millisec.). This fact verifies that naming is a longer process than reading, the difficulty of perceiving the stimulus being equal.

The response “zero” which may be given to the same sign is nearer to the reading-response time than the naming-response. These facts can be explained if we say that uncertainty for coding concrete signs is greater than for alphabetical or numerical signs.     

Visual vs. verbal stimulus set in a letter-classification task

In three experiments, subjects classified briefly presented letters as belonging to either the first or the second half of the alphabet. Prior to each target letter, the subjects were given either a verbally named letter (verbal set), a letter presented visually for 3 sec (visual set), or no prior alternative (control). The target was equally likely to be the same as the prior alternative (same trials) or from the opposite half of the alphabet (different trials). Classification accuracy was always greater for visual set than for the control condition. Verbal-set accuracy was no better than control accuracy when the verbal alternative immediately preceded the target but was equal to visual-set accuracy when the alternative preceded the target by 3 sec. In both set conditions, subjects tended to choose the same half of the alphabet as the prior alternative. It was concluded that type and timing of prior alternatives are important variables in accounting for enhanced classification accuracy.     

The effects of stimulus set size and word frequency on verbal serial recall

Two experiments are reported which examine immediate serial recall for high- and low-frequency words. The words in each list were either repeatedly drawn from the same small pool of candidates (in the closed set conditions) or each word only ever occurred once during the experiment (in the open set conditions). The results consistently show an effect of word frequency but the effect of set size was only apparent for low-frequency words. It is argued that both frequency and set size effects reflect processes concerning the "clean-up" of degraded short-term memory traces.     

The effects of stimulus set size and word frequency on verbal serial recall

Two experiments are reported which examine immediate serial recall for high-and low-frequency words. The words in each list were either repeatedly drawn from the same small pool of candidates (in the closed set conditions) or each word only ever occurred once during the experiment (in the open set conditions). The results consistently show an effect of word frequency but the effect of set size was only apparent for low-frequency words. It is argued that both frequency and set size effects reflect processes concerning the “clean-up” of degraded short-term memory traces.     

Forgetting of stimulus attributes: methodological implications for assessing associative phenomena.

Differential responding to changes in the stimulus situation, long central to the concept of stimulus control, also provides the implicit conceptual basis for assessing the nature of a variety of associative relationships. However, there is substantial evidence that the perception of stimulus similarity is not a static property. Generalization gradients to contextual as well as discriminative stimuli flatten over time, and this increase in perceived similarity presumably reflects forgetting of the detailed characteristics or attributes of stimuli. Methodologically, the flattening of the gradient imposes an important constraint: The effect of a stimulus shift will be highly sensitive to the length of the delay interval between training and testing. Conceptually, the loss of memory for stimulus attributes also implies that the sources of interference in retention can increase over time.     

Tarski hierarchies

The general notions of object- and metalanguage are discussed and as a special case of this relation an arbitrary first order language with an infinite model is expanded by a predicate symbol T₀ which is interpreted as truth predicate for . Then the expanded language is again augmented by a new truth predicate T₁ for the whole language plus T₀. This process is iterated into the transfinite to obtain the Tarskian hierarchy of languages. It is shown that there are natural points for stopping this process. The sets which become definable in suitable hierarchies are investigated, so that the relevance of the Tarskian hierarchy to some subjects of philosophy of mathematics are clarified.It should be noticed that these terms object language and meta language have only a relative sense. If, for instance, we become interested in the notion of truth applying to sentences, not of our original object-language, but of our meta-language, the latter becomes automatically the object-language of our discussion; and in order to define truth for this language, we have to go to a new meta-language — so to speak, to a meta-language of a higher level. In this way we arrive at a whole hierarchy of languages.(Tarski, 1986, p. 674f)     

On multiple verbal codability of objects

Summary The speaker can encode one and the same object S in variable ways in order to enable a listener to identify this particular object. It can be demonstrated that, among other things, the labeling of S depends on the context objects S_C that are presented with S, and with which S may be confused. Generally, speakers label the one feature of S which, within a given context, exclusively refers to S and not to any other object S_C. If there are several features coinciding with this condition (multiple codability), (1) the labeling covaries with the discriminability of S: the feature which is labeled is that which permits the best subjective discrimination of S as opposed to S_C; (2) the labeling covaries with the dimensional preference of the speaker in case the best discrimination proves impossible: the feature of S which is labeled is that which the speaker prefers as a result of his learning history. These theoretical assumptions listed above are investigated in two independent experiments (subjects: N=110 children; experimental material: geometric figures). The results largely confirm the theoretical considerations.This research was carried out with the help of a grant from the Deutsche Forschungsgemeinschaft.