Intertrial intervals and visual habituation in neonates

Eighteen 3-day-old human neonates were shown a 12 by 12 black-white checkerboard target for 45-sec. trials with either a 10-, 20-, or 30-sec. intertrial interval until their visual fixation time decreased to a set criterion for habituation. On subsequent recovery trials, a 2 by 2 black-white checkerboard target received significantly longer fixations from boys in the 10-sec. and girls in the 20-sec. conditions. 30-sec. intervals, however, produced little habituation and recovery. The implications of these findings are discussed.     

The development of depth perception from motion parallax in infancy

North Dakota State University, Fargo, North Dakota Little is known about infants' perception of depth from motion parallax, even though it is known that infants are sensitive both to motion and to depth-from-motion cues at an early age. The present experiment assesses whether infants are sensitive to the unambiguous depth specified by motion parallax and, if so, when this sensitivity first develops. Eleven infants were followed longitudinally from 8 to 29 weeks. Infants monocularly viewed a translating Rogers and Graham (1979) random-dot stimulus, which appears as a corrugated surface to adult observers. Using the infant-control habituation paradigm, looking time was recorded for each 10-sec trial until habituation, followed by two test trials: one using a depth-reversed and one using a flat stimulus. Dishabituation results indicate that infants may be sensitive to unambiguous depth from motion parallax by 16 weeks of age. Implications for the developmental sequence of depth from motion, stereopsis, and eye movements are discussed.     

Facilitation of food-reinforced responding by a signal for response-independent food

Five pigeons whose key pecking was maintained by 4-sec access to grain on a variable-interval 2-min schedule received Pavlovian differential conditioning trials superimposed upon the instrumental baseline. The conditioned stimuli were changes in the stimulus on the key from white to red, or to a white horizontal line against a dark background. The positive conditioned stimulus was 20 sec long, and was followed immediately by 8-sec access to grain. The negative conditioned stimulus, also 20 sec long, was never paired with response-independent food. All pigeons responded more rapidly in the presence of the positive conditioned stimulus than in the presence of the negative one. The positive conditioned stimulus produced an increase in response rate over the pre-conditioned stimulus period. The negative conditioned stimulus had no marked effect upon response rate. When the roles of the positive and negative stimuli were reversed, and the duration of the response-independent reinforcement was reduced to 4 sec, the new positive conditioned stimulus came to facilitate responding, and the new negative conditioned stimulus no longer produced facilitation. A second discrimination reversal produced similar outcomes. When a third reversal was initiated, and the duration of response-independent reinforcement was reduced to 2 sec, the difference between the effects of the positive and negative stimuli diminished.     

Elicitation and Inhibition of Competitive Fighting in Food Deprived Mice

Habituation as an index of the intrasensory and intersensory integration of form was investigated in nine-year-old children. In Habituation Period One, Ss were habituated to either a visual or a haptic 14″-perimeter standard stimulus. During Habituation Period Two, groups were subdivided and presented with one of the following stimuli: (a) 14″ visual, (b) 16″ visual, (c) 14″ haptic, or (d) 16″ haptic. The dependent variables were GSR frequency and amplitude, visual fixation time, and touching time. Subjects required more trials to habituate to the different stimulus presented in Habituation Period Two than Ss who received repeated presentations of the same stimulus. GSR frequency and amplitude habituated more consistently than did fixation and touching response measures. The results supported the use of the habituation paradigm for the study of intersensory and intrasensory integration, as well as providing support for extending Sokolov's theory to intersensory functions.     

Paired comparison scaling of reaction potential in two different experiments on habituation

Thurstone’s method of paired comparisons was employed to obtain scaled values of reaction potential from two completely different experimental situations involving response decrement. The first was one in which the GSR was measured on 10 repeated presentations of a visual stimulus (N= 89). The second involved 80 presentations of ordinary visual scenes; the S looked at each scene as long as he wished before switching to the next (i.e., looking time was measured. N=80). Scaling reaction potential by Thurstone’s method provided a common operational definition for both sets of data and permitted their direct comparison in identical units. Both measures showed substantial decrement in reaction potential across stages, with the GSR scale values dropping steeply from the first to the second trial and. thereafter, following a course of decline similar to the looking time scale values. Tlie correlation of the two sets of scale values was essentially linear and equalled 0.90.     

Looking time: The effects of stimulus complexity and familiarity

During a 10 min. stimulus familiarization period, three groups of 60 Ss each received either 0, 10, or 20 sec. of familiarization on each of 30 experimental stimuli: 10 each of low, medium, and high stimulus complexity. All Ss then viewed the experimental stimuli in a second task, during which they could look at each stimulus for as long as they wished (free looking). For half the Ss in each group, free looking was administered immediately after the familiarization period. The remaining Ss received free looking 48 hr. later. The results replicated earlier research which has shown that free looking time is inversely related to stimulus familiarity, and directly related to stimulus complexity. Unlike earlier findings, the data suggested that with a 48 hr. delay between familiarization and free looking, a stimulus can, at least partially, recover from the decrement in looking time produced by 10 sec. of familiarization.     

GSR amplitude instead of GSR magnitude: Caveat emptor!

Size of GSR made by 300 Ss to 20 repetitions of a visual stimulus is presented as mean magnitude and mean amplitude, illustrating that the amplitude method (averaging only those responses which are greater than zero) is susceptible to distortion resulting from a systematic elimination of Ss who initially make small responses. From trial to trial, the amplitude function comes more and more to be due to the behavior of Ss who initially make large responses. Even though the latter Ss’ responses actually reduce across trials, the amplitude function rises. Magnitude (including zeroes) docs not suffer from this distortion. It is suggested that the definition of a zero response is the source of the problem.     

Sleep and overextinction of the GSR component of the orienting response

Overextinction of the GSR component of the orienting response was examined in a sample of 68 socially disturbed adolescents. Continued stimulus repetition beyond the point of habituation resulted in GSR return after 50–60 stimulus presentations. However, division of Ss into sleep and non-sleep groups using behavioral and self-report criteria, failed to support Sokolov’s (1963) notion that overextinction is accompanied by drowsiness. A possible explanation of these results is discussed.     

Habituation of the visual orienting response in young children1, 2

The eye tracks of 29 children (aged 2-7 years) were recorded by a reflection eye camera while they were looking ata4by 4 matrix of 16 white geometric shapes. When a circle suddenly changed to red, the children immediately looked at it for two-thirds of the presentation time, a reading which was 16 times the initial level before this novel color was introduced. With repeated presentations of the novel red circle display, progressively fewer fixations fell on the red circle. After 20 trials, this habituation was incomplete, and the red circle was still drawing six times the initial amount of looking found on the original white circle. Ss were apparently relatively slow to form a neural representation of the visual environment due to the wide range of choices in the original display. The age of the children had no monotonic effect on the high, and virtually equal, initial visual concentration, nor on the rate at which habituation occurred. An interesting contrast, therefore, appeared between these data and the marked age effects noted by others in the recognition of letter-like shapes. Unlike recognition tasks, orienting and habituation need a minimum of stimulus interpretation. Children, even as young as 2 years, have demonstrated a remarkable efficiency in these processes of orienting and habituation to novelty.     

Stimulus novelty and intraseries primacy in GSR adaptation

GSR records were obtained for four groups of 20 Ss. Group I was presented with a series of four different lights (amber, blue, green, and white) appearing 20 times each, in apparent random order. The procedure was similar for the other three groups except that in group 2, a novel stimulus (a red light) appeared instead of the sixth amber light; in group 3, it appeared instead of the 16th amber light; and, in group 4, it appeared instead of the 16th amber light. Typical GSR adaptation phenomena were observed in all groups. The introduction of the novel stimulus appeared to have no effect on the course of GSR adaptation.     

Stimulus novelty and intraseries primacy in GSR adaptation

GSR records were obtained for four groups of 20 Ss. Group I was presented with a series of four different lights (amber, blue, green, and white) appearing 20 times each, in apparent random order. The procedure was similar for the other three groups except that in group 2, a novel stimulus (a red light) appeared instead of the sixth amber light; in group 3, it appeared instead of the 11th amber light; and, in group 4, it appeared instead of the 16th amber light. Typical GSR adaptation phenomena were observed in all groups. The introduction of the novel stimulus appeared to have no effect on the course of GSR adaptation.     

Operant acceleration during a pre-reward stimulus

Stimuli of 20, 40, and 80 sec duration terminated with five non-response-contingent food pellets were superimposed upon lever pressing reinforced with single pellets on a DRL 30-sec schedule. Two rhesus monkeys served as subjects. No change in response frequency was observed during the 20- and 40-sec stimuli. During the 80-sec pre-food stimulus, overall response frequency increased to approximately 150% and 220% of pre-stimulus levels, and the temporal distributions of interresponse times shifted toward the shorter intervals. When the 80-sec stimulus was no longer terminated with food, the response frequency decreased and the temporal distributions of interresponse times gradually approached pre-stimulus levels. An increased frequency of short interresponse times and an increase in response rate was again observed when the pellet termination procedure was reinstituted with the 80-sec stimulus. No change in response frequency or interresponse times was observed in the absence of the conditioning stimulus, and performance efficiency, as reflected in the ratio of responses to reinforcements during non-stimulus periods, remained stable throughout the experiment.     

The effect of change in sequential visual stimuli on GSR adaptation: II,the novel stimulus as a disinhibiting stimulus

GSR records were obtained for 20 Ss presented with a series of 80 stimuli (four lights alternating in apparent random sequence). Records were obtained, also, for 20 Ss in each of two groups, using the same procedure: in Group 1, a tone was substituted for one of the lights, early in the sequence, and in Group 2, it was substituted later in the sequence. The tone, the novel stimulus, produced significant changes in the GSR adaptation patterns of the two groups.     

Reliability and Specificity of Individual Differences In Reminiscence

In investigating Eysenck’s (1965) suggestion of the specificity of reminiscence, 50 high school boys were tested on 2 gross motorcoordination tasks—one involving tracking and the other balance. In the practice schedule, which was identical for both tasks, all Ss were given 20 50-sec. trials with a 10-sec. intertrial rest. A 5-min. interpolated rest was given after every fourth trial. The reliability of individual differences in reminiscence for both tasks was found to be extremely low. While Eysenck’s hypothesis was not necessarily weakened, doubt was cast upon the specificity of reminiscence in the usual context of the word.     

Reliability of electrodermal habituation measures under two conditions of stimulus intensity

The present study investigated test-retest reliability of habituation of the evoked skin conductance response. Subjects received 20 presentations of a 1000-Hz, 3-sec tone at the same time of day on two separate occasions, separated by an interval of 97–160 days. Thirteen subjects received stimuli of 90 dB, while for 24 subjects, stimulus intensity was 70 dB. Interstimulus interval was 21 sec for both groups. Both absolute rate of habituation and trials to criterion displayed moderate reliability, and the relationships between habituation measures and other aspects of electrodermal activity were in agreement with previous findings.     

Autonomy in Action: Linking the Act of Looking to Memory Formation in Infancy via Dynamic Neural Fields

Looking is a fundamental exploratory behavior by which infants acquire knowledge about the world. In theories of infant habituation, however, looking as an exploratory behavior has been deemphasized relative to the reliable nature with which looking indexes active cognitive processing. We present a new theory that connects looking to the dynamics of memory formation and formally implement this theory in a Dynamic Neural Field model that learns autonomously as it actively looks and looks away from a stimulus. We situate this model in a habituation task and illustrate the mechanisms by which looking, encoding, working memory formation, and long‐term memory formation give rise to habituation across multiple stimulus and task contexts. We also illustrate how the act of looking and the temporal dynamics of learning affect each other. Finally, we test a new hypothesis about the sources of developmental differences in looking.     

The Effect of Remoteness on Intertrial Correlations in Pursuit Rotor Performance

120 male university students were tested on a Koerth pursuit rotor. One group of 60 Ss was tested on each of 6 days spaced throughout a 3-wk. period. Another group of 60 Ss performed the same task in an identical manner for test-retest days only, with the retest day following by 3 wk. One group had a large amount of practice while the other did not within a comparable time period. Each practice session consisted of 60 15-sec. trials. The effects of both practice and layoff on intertrial correlations separated by increasing remoteness was investigated. The findings indicated, as others have found, that correlations decrease in size as remoteness increases. Adjacent trial correlations were found to increase as practice increased.     

Effects of auditory frequency-shifts on zero and below-zero SCR habituation

The purpose of the present experiment was to test a procedure for the measurement of effects of zero- and below-zero habituation (BZH) on responding to frequency shifts in auditory stimuli. The present procedure avoided some of the drawbacks of other procedures, that is, long duration, ambiguity in the definition of BZH, and inadequate control procedures. Two groups received 18 stimulus presentations each; group 1 received first a tone of 1000 Hz 12 times, then 1400 Hz (test stimulus 1) 3 times, and 1850 Hz (test stimulus 2) 3 times. Group 2 received the same stimuli, but 3, 12, and 3 times, respectively. The procedure had the advantages of short duration of the experiment, zero habituation and BZH were operationally defined (as 3 and 12 stimulus presentations, respectively), and there were adequate control conditions since a control group that did not receive stimulus change on the relevant trial was employed. The results showed no effects of stimulus shifts on responding to the test stimuli. Group 2 responded significantly less than group 1 across trials, though, and this may be explained by an inhibitory process elicited by changes in weak stimulation during the habituation process.     

Salivary responding and the duration of measurement

The Strongin-Hinsie Peck whole-mouth salivation measure (Peck, 1959) is typically collected for a 2-min duration. This study compared saliva collected for 120 sec with saliva collected for shorter durations (30 and 60 sec) over repeated presentation of gustatory cues. Results showed reliable increases in salivation from a water stimulus baseline to the first presentation of lemon juice as a function of measurement duration. Repeated measures analysis of variance showed overall decreases in salivation across each measurement duration, with a greater rate of habituation for the 120-sec interval than for the 30- and 60-sec intervals. These data suggest that shorter measurement intervals can be used to measure salivation in acute and repeated measurement paradigms, but the change in response to repeated stimulus presentations is more pronounced for the longer measurement duration.     

The effect of rate of presentation

Two experiments investigated the effect of a pre-test series of pictures, presented at a fixed rate, upon Ss subsequent free looking time. The results indicated that high fixed rates of presentation (3 sec./presentation) reduced \ldnatural\rd looking times, and low fixed rates of presentation (15 or 60 sec./ presentation) increased natural looking times. The results were interpreted within an adaptation level theory framework. Accordingly, the fixed rate serves as an anchor which influences Ss \ldnatural\rd looking time. Evidence was also found suggesting that a simple imitation interpretation is questionable.