From previous research, we expected to find a two main factor solution: Affective Valence, comprising affective valence ratings, magnitude, and latency of the startle reflex, and heart-rate change, and Arousal, made up of arousal ratings, SCR, and picture-viewing time.
The data of one subject were unavailable for startle blink reflex (n = 44), heart-rate data of one subject were discarded from statistical analysis due to intractable recording artifacts (n = 44), and SCR data of one subject were discarded due to a low rate of responses (< 2; n = 44).
Startle probes were presented at two of three pictures of each affective category per block, at a random time between 3500 and 4500 ms after picture onset.
The acoustic startle stimulus was a 50-ms 105-dB(A) burst of white noise (20 Hz-20 kHz) with instantaneous rise- and fall-times, presented binaurally through Sony MDR-P70 headphones, and generated by a custom-made noise acoustic stimulator from the facilities of the University of Murcia.
Startle blink reflex was measured by recording EMG activity from the orbicularis oculi muscle beneath the left eye, using a bipolar placement of 4-mm Ag/AgCl surface electrodes (Fridlund & Cacioppo, 1986).
If the resident is hitting because of an exaggerated startle
response, the caregiver should approach from the front with a smile, being sure to gain the resident's attention and to precede the physical contact with eye contact.
Some psychologists believe that the startle reaction, which has been examined by numerous researchers since 1939, lies at the far end of the emotion of surprise and provides a good model for the study of other emotions.
Detailed measurements of facial muscles during the startle reaction suggest that it is probably a reflex, according to a report in the November JOURNAL OF PERSONALITY AND SOCIAL PSYCHOLOGY.
The researchers examined the startle reactions of 17 healthy individuals who, on different occasions, did or did not know when a blank pistol would be fired.
With emotions such as surprise, happiness and disgust, note the researchers, facial expressions can be inhibited and simulated fairly successfully and are far more difficult to elicit experimentally than is the startle reaction.