The Ringelmann effect: Studies of group size and group performance

Ringelmann's classic finding—that the addition of co-workers in a rope-pulling task leads to a linear decrement in the individual group member's average performance—was reexamined experimentally. Study I attempted to replicate the effect, using groups of subjects ranging in size from 1 to 6. Performance dropped significantly as group size was increased from one individual to two or to three, but the addition of a fourth, fifth, or sixth member produced insignificant additional decrements; thus, the effect was not linear but curvilinear. Study II was designed to examine possible sources of performance loss, separating the factors of “coordination” and “motivation” loss (Steiner, 1972). The possibility of intermember incoordination was eliminated, while motivation loss remained free to vary: Each experimental subject pulled alone, and in “groups” where he believed there were from one to five other members. Once again, individual performance declined significantly with the addition of the first and second perceived co-worker, but then leveled off for perceived group sizes three to six. Some implications are discussed.     

Some analyses of the verbal encoding deficit of alcoholic Korsakoff patients

Two experiments were designed to assess Korsakoff patients' ability to encode verbal information on the basis of its physical, nominal and semantic properties. The first investigation employed Wickens' release from proactive interference (PI) technique; a procedure that allows an assessment of a subject's ability to encode verbal information on the basis of its semantic properties. It was discovered that on tasks involving only a rudimentary verbal analysis, such as the ability to discriminate letters from numbers, the Korsakoff patients demonstrated a normal release from PI. However, on tasks that required a more sophisticated level of semantic encoding, such as those based on taxonomic class inclusion, the patients failed to show release from PI. The second investigation employed Posner's reaction time technique which assesses a subject's ability to encode the physical and nominal properties of simple verbal materials (letters). The results of this study showed that Korsakoff patients are impaired on even these rudimentary encoding tasks, which led to the proposal that Korsakoff patients' semantic encoding deficit might stem from an initial impairment in the speed at which physical and nominal properties of verbal information are analyzed.     

Self-directed desensitization for acrophobia

Acrophobic outpatients received therapist- or self-directed (tape-recorded) desensitization in a study of (a) treatment effectiveness with diminished therapist contact ; (b) subject characteristics ‘predicting’ outcome; and (c) generalization of change. At Post-test, treated Ss (N=16) had improved significantly more than Waiting List Ss (N=13) on self-report measures of acrophobia and general anxiety, while the treatment methods were equally effective. An 8-month follow-up found that self-directed Ss had attempted more specific behavioral situations than therapist-directed Ss, and showed additional gains on self-report measures while therapist-directed Ss maintained post-test levels. Results suggested: (a) desensitization provides effective treatment even with reduced therapist contact; (b) some subject characteristics relate to outcome and (c) treatment effects generalize to other anxiety indices.     

Effects of self-attributed and other-attributed gaze on interpersonal evaluations between males and females

Male and female subjects were placed together in pairs for 10 min to get to know each other and talk about anything they wished. After the conversation, an experimenter gave the participants false feedback about the amount of gaze between them during the conversation. One subject (designated Self) was reported by the experimenter to have gazed at the Other at a higher level than usual for most people, at an average level, or at a lower level than usual for most people. After the conversation and the false feedback manipulation, subjects evaluated each other on a rating form. Results of the experiment showed that females gave males the most favorable ratings when they had ostensibly gazed at the males at a high level. Males were most favorable toward females when they thought they had given the females low levels of gaze. When considering the gaze of the other person, both male and female subjects rated a low gazing partner as least attentive and a high gazing partner as most sincere. Males rated low gazing females as least attractive. Females rated males with high reported gaze as least attractive. The research was discussed in terms of Bem's theory that attitudes are a function rather than a cause of behavior. Results were integrated with past research and suggestions for further study were made.     

Effects of sound frequency on behavioral and cardiac orienting in newborn and five-month-old infants

Alert newborn and 5-month-old infants' responsivity to variations in spectral composition of a rattle sound was examined. Each child received four stimulus conditions: low-, mid-, and high-frequency bandpass-filtered rattles and an unfiltered broadband rattle. Stimuli were played through a single loudspeaker laterally positioned, and head orientation and cardiac responses to sound were recorded. Compared to other stimuli, the low-frequency sound elicted less head turning in both age groups, with this effect exaggerated in younger infants. Head orientation toward the mid-frequency, high-frequency, and broadband stimuli did not differ with age. For all conditions, latency and duration of newborns' head turning was longer than that of 5-month-olds. Newborns responded with cardiac deceleration only on trials when they failed to turn. When head turns occurred, an acceleratory cardiac response was obtained. Five-month-olds responded with reliable cardiac deceleration irrespective of head turning toward the sound. Heart rate change did not vary as a function of frequency at either age, suggesting that all stimuli were equally effective in eliciting the infant's attention.     

The influence of various types of control on psychophysiological stress reactions

The influence of personal control on reactions to shock was found to differ not only as a function of the type of control, but also as a function of the combination of control conditions. For example, behavioral control in the presence of information (cognitive control) reduced stress, whereas behavioral control in the absence of information augmented stress. These results are discussed with regard to the appropriateness of two different models, a “substitutive” versus an “interactive” model, for understanding the effects of personal control.     

Speech timing of grammatical categories

A series of experiments was performed to determine how the duration of a word spoken in a sentence is influenced by: (1) the grammatical category to which it belongs, and (2) the position of the word in a constituent. Experiment I contained Noun-Verb homophones (e.g. “I saw the coach…” — noun; “I saw him coach…” — verb), in sentences matched for phonetic environment and stress pattern. Results support the notion that Nouns are longer than Verbs in typical sentences. Experiment II, however, demonstrated that the duration of Noun-Verb homophones in matched clause-final position is approximately equal. Experiment III contained transitive and intransitive Verbs in matched sentences. The results of Experiments II and III provided support for a lengthening account based on constituent-final position, while ruling out an account based on a debatable deletion site. Results of Experiment IV generalized the account of constituent-final lengthening for Nouns and Verbs to additional major categories, by comparing the duration of the phrase-initial Adjective two with the phrase-final Adverb too. Finally, Experiment V tested the distinction between minor and major categories. Results demonstrated that the Preposition to is shorter than the Adjective two by approximately 50 percent. Taken in sum, these findings indicate that it is sufficient to make a binary distinction between major and minor categories for purposes of a theory of speech timing and speech synthesis. Durational effects traditionally ascribed to differences within the class of major categories can be accounted for solely in terms of constituent boundaries, already required in the theory to account for three other classes of phenomena.     

Three conditions on conceptual naturalness

Human infants are predisposed to organize their experience in terms of certain concepts and not in terms of others. The favored concepts are called natural, the remainder, unnatural. A major problem in psychology is to state a principled distinction between the two kinds of concepts. Toward this end, the present paper offers three, formal necessary conditions on the naturalness of concepts. The conditions attempt to link the problem of naturalness to the distinctions between sense versus nonsense, simplicity versus complexity, and validity versus invalidity.     

Alcoholic Korsakoff patients' retrieval from semantic memory

Alcoholic Korsakoff patients' rate of retrieval from semantic memory was investigated. It was found that their rate of retrieval from “lexical” semantic memory was nearly normal, but their rate of retrieval from “conceptual” semantic memory was impaired. In addition, an attempt to “prime” their lexical semantic memory by requesting the same category to be searched on adjacent trials met with failure. It was concluded that Korsakoff patients' lexical storage is probably organized normally, but their conceptual organization is not. Parallels with these patients' episodic memory impairments are discussed and possible interactions between episodic and semantic memory are proposed.     

The functional equivalence of mental images and errors of movement.

Four experiments are reported demonstrating that mental images are functionally equivalent to physical errors of movement in producing changes in visual-motor coordination, at both central and peripheral levels of the visual-motor system. In the first experiment, subjects in one condition pointed at a target seen through laterally displacing prisms and were instructed to imagine pointing errors identical to those recorded previously for subjects in a separate condition who actually observed their pointing errors. Changes in pointing accuracy during adaptation procedures and visual-motor aftereffects following these procedures for subjects who imagined their errors were proportional to visual-motor shifts and aftereffects for subjects who observed their errors. In the second experiment, these same imagery instructions resulted in identical pointing shifts and aftereffects even in the case where prisms did not displace the target. The third experiment showed that when subjects believe that their mental images of pointing errors do not correspond to their actual pointing errors, pointing aftereffects result that are characteristic of the processing of error information at peripheral, but not central, levels of the visual motor system. The final experiment showed that when subjects do believe that their images of pointing errors correspond to actual pointing errors, but imagine the pointing movement itself in addition to their errors, pointing aftereffects result that are characteristic of the processing of error information at central, but not peripheral, levels of the visual-motor system. Contributions to visual-motor aftereffects from these two levels appear to be additive. Another significant result was that, in the imagery feedback conditions of each experiment, subjects who gave high ratings of vividness to their mental imagery showed the greatest magnitude of pointing aftereffects. These findings establish that mental images for errors of movement can produce stable visual-motor changes that cannot be accounted for simply by subjects' expectations regarding the actual consequences of their actions.