Lifespan Development. Tara L. Kuther

Visual development by Marcela Salamanca and Donald Kline, University of Calgary (http://psych.ucalgary.ca/PACE/VA-Lab/). Reprinted by permission of the authors.

      Habituation improves with development. For example, the performance of fetuses on habituation tasks improves with gestational age (James, 2010). After birth, habituation is often measured by changes in an infant’s heart rate and in attention or looking at a stimulus (Domsch, Thomas, & Lohaus, 2010). Younger infants require more time to habituate than older infants (Kavšek & Bornstein, 2010). Five- to 12-month-old babies habituate quickly—even after just a few seconds of sustained attention—and in some cases, they can recall the stimulus for weeks, such as recalling faces that they have encountered for brief periods of time (Richards, 1997).

      Neural development, specifically development of the prefrontal cortex, is thought to underlie age-related gains in habituation skill (Nakano, Watanabe, Homae, & Taga, 2009). As the brain matures, infants process information more quickly and learn more about stimuli in fewer exposures. Younger infants and those with low birthweight require more time to habituate than do older and more fully developed infants (Kavšek & Bornstein, 2010; Krafchuk, Tronick, & Clifton, 1983; Rovee-Collier, 1987). Fetuses with more mature nervous systems require fewer trials to habituate than do those with less well-developed nervous systems, even at the same gestational age (Morokuma et al., 2004). Fetal habituation predicts measures of information processing ability at 6 months of age (Gaultney & Gingras, 2005).

      There are also individual differences in habituation among healthy, developmentally normal infants. Some habituate quickly and recall what they have learned for a long time. Other infants require many more exposures to habituate and quickly forget what they have learned. The speed at which infants habituate is associated with cognitive development when they grow older. Infants who habituate quickly during the first 6 to 8 months of life tend to show more advanced capacities to learn and use language during the second year of life (Tamis-LeMonda, Song, & Bornstein, 1989). Rapid habituation is also associated with higher scores on intelligence tests in childhood (Kavšek, 2004). The problem-solving skills measured by intelligence tests tap information processing skills such as attention, processing speed, and memory—all of which influence the rate of habituation (McCall, 1994).

      Innate learning capacities permit young infants to adapt quickly to the world, a skill essential for survival. Researchers use these capacities to study infant perception and cognition (Aslin, 2014). For example, to examine whether an infant can discriminate between two stimuli, a researcher presents one until the infant habituates to it. Then a second stimulus is presented. If dishabituation, or the recovery of attention, occurs, it indicates that the infant detects that the second stimulus is different from the first. If the infant does not react to the new stimulus by showing dishabituation, it is assumed that the infant does not perceive the difference between the two stimuli. The habituation method is very useful in studying infant perception and cognition and underlies many of the findings discussed later in this chapter.

      Classical Conditioning

      In addition to their capacity to learn by habituation, infants are born with a second powerful tool for learning. They can learn through association. Classical conditioning entails making an association between a neutral stimulus and an unconditioned stimulus that triggers an innate reaction. Eventually, the neutral stimulus (now conditioned stimulus) produces the same response as the unconditioned stimulus.

      Newborns demonstrate classical conditioning. For example, when stroking the forehead was paired with tasting sugar water, 2-hour-old infants were conditioned to suck in response to having their heads stroked (Blass, Ganchrow, & Steiner, 1984). Similarly, Lipsitt and Kaye (1964) paired a tone with the presentation of a nipple to 2- and 3-day-old infants. Soon, the infants began to make sucking movements at the sound of the tone. Sleeping neonates can be conditioned to respond to a puff of air to the eye (Tarullo et al., 2016). Even premature infants can demonstrate associative learning, although at slower rates than full-term infants (Herbert, Eckerman, Goldstein, & Stanton, 2004). Research with chimpanzee fetuses has shown that they display classical conditioning before birth (Kawai, 2010). It is likely that the human fetus can as well. Although classical conditioning is innate, neurological damage can hinder infants’ abilities to learn by association. Infants with fetal alcohol syndrome (FAS) require much more time than other infants to associate eye blinking with external stimuli, such as sounds (Cheng et al., 2016).

      Newborns tend to require repeated exposures to conditioning stimuli because they process information slowly (Little, Lipsitt, & Rovee-Collier, 1984). As infants grow older, classical conditioning occurs more quickly and to a broader range of stimuli. For example, in a classic study, Watson and Raynor (1920) paired a white rat with a loud banging noise to evoke fear in an 11-month-old boy known as Little Albert. Repeated pairings of the white rat with the loud noise made Albert cry even when the rat was presented without the noise. In other words, Little Albert was conditioned to associate the neutral stimulus with the conditioned stimulus. Albert demonstrated fear in response to seeing the rat, indicating that emotional responses can be classically conditioned. Our capacities to learn through classical conditioning are evident at birth—and persist throughout life.

      Operant Conditioning

      At birth, babies can learn to engage in behaviors based on their consequences, known as operant conditioning. Behaviors increase when they are followed by reinforcement and decrease when they are followed by punishment. For example, newborns will change their rate of sucking on a pacifier, increasing or decreasing the rate of sucking, to hear a tape recording of their mother’s voice, a reinforcer (Moon, Cooper, & Fifer, 1993). Other research shows that newborns will change their rate of sucking to see visual designs or hear human voices that they find pleasing (Floccia, Christophe, & Bertoncini, 1997). Premature infants and even third-trimester fetuses can be operantly conditioned (Thoman & Ingersoll, 1993). For example, a 35-week-old fetus will change its rate of kicking in response to hearing the father talk against the mother’s abdomen (Dziewolska & Cautilli, 2006).

      As infants develop, they process information more quickly and require fewer trials pairing behavior and consequence to demonstrate operant conditioning. It requires about 200 trials for 2-day-old infants to learn to turn their heads in response to a nippleful of milk, but 3-month-old infants require about 40 trials, and 5-month-olds require less than 30 trials (Papousek, 1967). Infants’ early capacities for operant conditioning imply that they are active and responsive to their environments and adapt their behavior from birth.

      Imitation

      Toddler Tula puts a bowl on her head and pats it just as she watched her older sister do yesterday. Imitation is an important way in which children and adults learn. Can newborns imitate others? Believe it or not, some research suggests that newborns have a primitive ability to learn through imitation. In a classic study (see Figure 4.7), 2-day-old infants mimicked adult facial expressions, including sticking out the tongue, opening and closing the mouth, and sticking out the lower lip (Meltzoff & Moore, 1977). The prevalence and function of neonate imitation is debated (Suddendorf, Oostenbroek, Nielsen, & Slaughter, 2013). Some studies have failed to replicate this ability (Oostenbroek et al., 2016) and have suggested that tongue protruding simply reflects a general spontaneous newborn behavior (Keven & Akins, 2017), that it reflects arousal (Vincini, Jhang, Buder, & Gallagher, 2017), and that neonate imitation is not developmentally similar to later social imitation (Suddendorf et al., 2013). Others have confirmed that newborns from several ethnic groups and cultures display early capacities for imitation (Meltzoff & Kuhl, 1994; Nadel & Butterworth, 1999). In one study, newborns made corresponding mouth movements to both vowel and consonant vocal models; when the adult model made an a sound, newborns opened their mouths, and when the model made an m sound, newborns clutched their mouths (Chen, Striano, & Rakoczy, 2004). Studies that require infants to imitate several behaviors in response to different stimuli suggest that neonate imitation is not simply an arousal response (Nagy, Pilling, Orvos, & Molnar, 2013).

      Newborns mimic facial