Stereopsis with opposite contrast contours

The effects of incidental stimuli, defined as visual stimuli not under verbal control, upon a selection task were observed as a function of feedback contingency. Ss judged letter pairs to be valid or invalid completions of preceding letter parts. During the presentation of the letter parts, the response pair or an alternative pair of letters was intermittently presented at a threshold value individually determined for each S. One group of Ss received a light feedback of performance contingent upon responding to the incidental stimuli; whereas a second group received a random noncontingent feedback. The results indicated: (a) both groups responded to the incidental stimuli; (b) feedback contingency had no effect on frequency of responding to the incidental stimuli; (c) frequency of responding to the incidental stimuli remained constant over 32 trials.     

The effects of familiarity and practice on naming pictures of objects

Ss were given a paired-associate learning task, using nonsense shapes as stimuli and object names which varied in Thorndike-Lorge frequency as responses. Between each block of learning trials, Ss named the nonsense shapes and a set of line drawings of objects. While naming latencies for the shapes were unaffected by name frequency, there was an effect of frequency on naming a control set of pictures of objects. The frequency effect for the pictures decreased significantly with practice. When the Ss were asked to name pictures of the objects having the names previously learned for the nonsense shapes, an effect of frequency appeared, the size of the effect being the same as that found for the control pictures after practice. The frequency effect disappeared when the shapes were reintroduced.     

Frequency and coding responses in verbal discrimination learning

Ss were given a verbal discrimination task where correct and incorrect stimuli appeared in one, two. or four different pairs in a within-Ss design. For a group tested with the usual anticipation procedure, correct repetitions helped and incorrect repetitions hurt performance. The pattern of results suggested that frequency is a salient cue in verbal discrimination learning but that coding or paired-associate processing may occur at the same time. Data from a second group of Ss for which frequency was a less salient cue gave more direct evidence for coding.     

Cognitive conditioning: Imagined stimulus contiguity and the third interval conditional GSR

The effect of repeatedly imagining paired or unpaired CSs and USs on the frequency of post-CS responses during real extinction was studied. Four groups of 10 Ss first received a model tone and shock. For two of the groups the stimuli were paired (delayed conditioning paradigm). For the others the stimuli were arranged in a long trace paradigm. The Ss then received a series of commands requiring them to imagine receiving paired CSs and USs, or to imagine the events singly. Then 10 real tone extinction trials were given. The groups which received delayed conditioning model stimuli were more responsive than trace groups, and groups which had imagined paired stimuli were more responsive than their unpaired controls. Cognitively oriented explanations of these findings were discussed.     

Stimulus familiarity,dogmatism, and the duration of attention

Thirtyeight males and 30 females viewed each of 30 black and white photographs for as long as they wished. Half the photographs were judged by the Es to be unfamiliar to college students. The remaining photographs were judged to be familiar. After the looking task all Ss cotnpleted the Dogmatism Scale. It was predicted that the open-minded Ss would spend more time looking at the novel stimuli than the closed-minded Ss, and, that all Ss would spend more time looking at novel stimuli than familiar stimuli. The results failed to confirm the hypothesis that open-minded Ss would look longer at the novel stimuli than closed-minded Ss. However, it was found that Ss spent more time looking at novel stimuli than familiar stimuli regardless of the degree to which their belief systems were opened or closed. The adwwtage of manipulating stimulus familiarity by E-selection of the stimuli was discussed.     

Idiosyncratic exceptions to the probability-matching decision-rule in visual discrimination

Human “Yes-No” signal-detection performance was tested under a modified perceptual-defense procedure. A majority of Ss tended to match the relative frequency with which they gave affirmative responses to the relative frequency at which signals were presented. These Ss thereby replicated the “probability-matching” behavior found in previous signal-detection and discrimination studies. However, in marked contrast to those previous results, another large set of Ss showed a tendency toward preponderant use of one of the two responses (typically, of “No”) rather than toward probability-matching. The evidence failed to suggest that the latter effect was related to a lesser ability to make the requisite sensory discrimination or to response inhibition induced by taboo stimuli.     

A constant error in the perception of brief temporal intervals

Ss were presented two stimuli of equal duration separated in time. The parrs of stimuli were vibrotactile, auditory, or visual. The Ss adjusted the time between the two stimuli to be equal to the duration of the first stimulus. The results show that for stimulus durations ranging from 100 to 1,200 msec, Ss set the tune between the two stimuli too long and by a constant amount. For vibrotactfle stimuli, the constant was 596 msec; for auditory stimuli, 657 msec; and for visual stimuli, 436 msec. Changing the intensity of the vibrotactile stimuli did not change the size of the constant error. When Ss were presented two tones with a burst of white noise between the tones and adjusted the duration of the white noise to be equal to the duration of the first tone, the white noise was not adjusted too long by a constant amount. The results suggest that there is a constant error in the perception of unfilled relative to filled temporal intervals.     

Perception of less irregular and more irregular stimuli.

Berlyne's stimuli were presented in a stereoscope to test his hypothesis that Ss prefer the more irregular member of a pair of stimuli. 32 Ss, screened for normal acuity and phorias, were tested. Contrary to Berlyne's hypothesis and consistent with earlier stereoscopic studies, Ss tend to report more frequently the less irregular member of a pair of stimuli. These data can be explained by an information-conflict model; however, the clearest implication of this study was that experiments concerned with familiarity of stimuli should be qualified by the method.     

Individual response patterns in binary choice tasks with nondiscriminable stimuli

The present experiment sought to determine whether individual Ss tend to employ repeatedly the same response patterns in binary choice tasks containing nondiscriminable stimuli and, if so, whether the response sequences when used to constructstimulus sequences improve the performance of other choice tasks. Information and frequency analyses of the response sequences of 48 Ss showed moderate consistency of patterning within a light and within a tone task. Performance of a card task following the light and tone tasks was closely related to the task (light or tone) from which the stimulus sequence was obtained. The frequency analysis showed that repetition patterns were preferred by most Ss but at the expense of alternation responses. The presentation of reinforcement in the card task did not improve performance over that observed in the light and tone tasks.     

The roles of practice and correction in the categorization of sour and bitter taste qualities

Ten Ss were selected from a group of 40 screened to determine misnaming of stimuli usually called sour (hydrochloric and citric acid) and bitter (quinine sulfate). The 10 Ss were then given 16 trials in which they were asked to match the stimuli to standards, with or without verbal feedback for each stimulus. This was followed by 16 trials without feedback for all Ss and, several days later, by a 16-trial posttest. Final improved performance of the Ss was not affected by having received the feedback. It was concluded that experience with the stimuli leads to a reduction in the degree of misnaming, implying a nonphysiological basis for sour-bitter confusions.     

Individual response patterns in binary choice tasks with nondiscriminable stimuli

The present experiment sought to determine whether individual Ss tend to employ repeatedly the same response patterns in binary choice tasks containing nondiscriminable stimuli and, if so, whether the response sequences when used to construct stimulus sequences improve the performance of other choice tasks. Information and frequency analyses of the response sequences of 48 Ss showed moderate consistency of patterning within a light and within a tone task. Performance of a card task following the light and tone tasks was closely related to the task (light or tone) from which the stimulus sequence was obtained. The frequency analysis showed that repetition patterns were preferred by most Ss but at the expense of alternation responses. The presentation of reinforcement in the card task did not improve performance over that observed in the light and tone tasks.     

Degree of training and the novelty transfer effect

Four groups of 40 Ss were given transfer tests following 2.4, 6, or 8 14-trial blocks of paired-associate training with unequal stimulus frequencies and then retested after a further training period in which the same compound stimuli were presented at equal frequencies. The novelty effect, in which Ss respond to new combinations of training components by giving the response associated with the least frequent component, was obtained in every transfer test. It was concluded that the novelty effect is a mode of responding that is produced by differential frequencies during early learning and which, once adopted, is retained by Ss regardless of whether the frequency differential is maintained.     

The computer as experimenter in social psychological research

The effects of familiarity and exposure paradigm on evaluative meaning were investigated in four experiments involving 161 Ss. A DEC PDP-10 computer linked to a VB10-C display screen for 1/0 assigned Ss to condition, presented instructions, tested Ss’ understanding of the instructions, generated and displayed stimuli in various frequencies, and obtained evaluative ratings of the stimuli. Problems encountered, Ss’ reactions, and current and possible use of the computer in social psychological research are discussed.     

Free sorting with stimuli clustered in a multidlmensional attribute space

An experiment was conducted to determine whether Ss leam, without knowledge of results or prior familiarization with the prototypes, to sort histoform stimuli generated by three probablistic rules into categories consistent with these mies. Seven Ss were asked to sort 30 stimuli (10 from each schema population) on each trial. No constraints were placed on the number of categories to be used. A statistic was developed to measure consistency between schema-defined categories and subjeet-defined categories. Four of the seven Ss met the leaming criterion, and demonstrated increasing consistency with the schema-defined categories across trials. In general, more categories than necessary were used to classify the stimuli correctly. The results raise several questions about classification strategies used by Ss in perceptual learning tasks with stimuli generated by probabilistic rules, and indicate the need for further research conceming the variables that influence perceptual category formation.     

Judgments of proportions

This study investigated the processes that underlie estimates of relative frequency. Ss performed 4 tasks using the same stimuli (squares containing black and white dots); they judged "percentages" of white dots, "percentages" of black dots, "ratios" of black dots to white dots, and "differences" between the number of black and white dots. Results were consistent with the theory that Ss used the instructed operations with the same scale values in all tasks. Despite the use of the correct operation, Ss consistently overestimated small proportions and underestimated large proportions. Variations in the distributions of actual proportions affected the extent to which Ss overestimated small proportions and underestimated large proportions in the direction predicted by range-frequency theory. Results suggest that proportion judgments, and by analogy probability judgments, should not be taken at face value.     

Effect of a mid-series anchor on absolute judgments of duration by schizophrenics, neurologically impaired, and normals.

36 normal, 36 schizophrenic, and 36 neurologically impaired Ss were compared for their ability to temporally discriminate brief auditory stimuli. The experimental task was the absolute judgment of 3, 5, or 9 stimuli ranging in duration from 0.10 to 1.90 sec. Half of the Ss in each group were "assisted" by the presentation of a repeated mid-series anchor. The interval between the presentation of the anchor and the variable stimuli was varied. With the addition of a mid-series anchor, normal Ss demonstrated an increase in information transmission and a decrease in response stereotypy; schizophrenics demonstrated a slight decrease in information transmission and a slight increase in response stereotypy; neurologically impaired Ss were essentially unaffected. Changes in interstimulus interval on the anchored judgment task did not influence information transmission.     

Choice reaction and unequal stimulus frequencies in an absolute judgment situation

Previous investigators have reported discrepant results for Ss in a choice reaction time (CRT) situation when stimuli are not equi-probable. Sixty Ss participated in an absolute judgment CRT task under three conditions of equi-probable stimuli and three of unequally probable stimuli. The results indicate that previous findings may be determined by a threshold dependent upon the effect of unequal stimulus frequencies and the utilities of different response strategies.     

Determinants of visual attention in real-wound scenes.

The present study examined the saliency of size, movement, and human content variables in visual selective attention. Ss named stimuli present in motion pictures of real world scenes or in animated cartoon controls during a 15-sec. exposure period. Regardless of the type of presentation that they saw, Ss tended to name large and/or moving stimuli more often than small and/or nonmoving stimuli. Also, small human stimuli were named more frequently than small nonhuman stimuli, while there were no differences between the frequencies with which large human and nonhuman stimuli were named. The order in which Ss named stimuli was not related to either the size, movement, or human content variables. Results are discussed in terms of the generalizability of the results of previous studies to conditions simulating the real world.     

Choice reaction and unequal stimulus frequencies in an absolute judgment situation

Previous investigators have reported discrepant results for Ss in a choice reaction time (CRT) situation when stimuli are not equi-probable. Sixty Ss participated in an absolute judgment CRT task under three conditions of equi-probable stimuli and three of unequally probable stimuli. The results indicate that previous findings may be determined by a threshold dependent upon the effect of unequal stimulus frequencies and the utilities of different response strategies.     

The influence of stimulus uncertainty and experimental instructions on visual selection

The looking behavior of adults and children was recorded while they viewed pairs of stimuli differing in stimulus uncertainty. Ss in one experimental group were encouraged to identify the stimuli and indicate whether they had been seen in a previous phase of the experiment. For the remaining Ss, instructions minimized the importance of the stimuli to the experiment. Results indicate that, when stimulus uncertainty was influential, the relationship between stimulus uncertainty and looking time was monotonically increasing. However, stimulus uncertainty was an effective determinant of looking behavior only when Ss were motivated to identify the stimuli. The behavior of adults and children did not differ.